Researcher basic information

• Ph.D.Science Kyoto University, Kyoto University, May 1996

• https://researchmap.jp/HASHIMOTO_Takeshi?lang=en

• https://jglobal.jst.go.jp/detail?JGLOBAL_ID=200901000069445606
• http://www.sci.hokudai.ac.jp/isv/
• http://uvo.sci.hokudai.ac.jp/~hasimoto/

• 200901000069445606

• 地下構造
• crater lake
• 自然電位
• 火山
• 火山ガス
• 水蒸気
• ラマンライダー
• 分光
• 熱収支
• SO2
• geomagnetism
• Volcanology
• 地球電磁気学
• 火山物理学

• Social Infrastructure (Civil Engineering, Architecture, Disaster Prevention), Disaster prevention engineering
• Natural Science, Solid earth sciences

• Bachelor's degree program, School of Science
• Master's degree program, Graduate School of Science
• Doctoral (PhD) degree program, Graduate School of Science

Research activity information

• 2020, 日本火山学会, 日本火山学会論文賞
  橋本武志・宇津木充・大倉敬宏・神田 径・寺田暁彦・三浦 哲・井口正人 (2019) 非マグマ性の火山活動に伴う消磁及び地盤変動のソースの特微. 火山, 64, 2, 103-119.
• Nov. 1998, Society of Geomagnetism and Earth, Planetary and Space Sciences, Ohbayashi Prize
  自然電位観測による雲仙普賢岳直下の熱水対流の発達過程の解明

• Pilot application of the Volcanic Unrest Index (VUI) for active volcanoes in Japan: Mount Tokachidake and Mount Meakandake
  Takeshi Hashimoto; Hiroshi Aoyama; Ryo Tanaka; Takahiro Ohkura; Toshiya Mori; Ryo Takahashi; Akimichi Takagi; Mare Yamamoto; Masahiro Ichiki; Wataru Kanda; Akihiko Terada; Mitsuru Utsugi
  Earth, Planets and Space, 78, 145, Springer Science and Business Media LLC, 30 Jun. 2026, [Peer-reviewed], [Lead author], [International Magazine]
  English, Scientific journal
• Dense magnetotelluric imaging of the Akan Caldera (Hokkaido, Japan): insights into its magma plumbing system and caldera-forming reservoir
  Tomohiro Inoue; Takeshi Hashimoto; Koki Aizawa; Hiroshi Ichihara; Ryo Tanaka; Yusuke Yamaya
  Earth, Planets and Space, Springer Science and Business Media LLC, 16 Mar. 2026, [Peer-reviewed], [International Magazine]
  English, Scientific journal, Abstract
  
  To investigate the magma plumbing system beneath the Akan Caldera (Hokkaido, Japan), we conducted broadband magnetotelluric surveys and imaged its three-dimensional resistivity structure to a depth of approximately 30 km. The caldera hosts post-caldera volcanoes, including Mt. Meakandake and Mt. Oakandake, which have recently shown ground inflation and heightened deep low-frequency seismicity. Our main finding is a prominent, westward-dipping conductive column beneath the caldera. This conductor is interpreted as the magma plumbing system of the Akan Caldera, comprising three distinct components, for which we estimated volumes based on the spatial extent of the conductive region: (1) the volatile-rich zone at depths of 2–5 km (~ 10 km ³ , < 10 Ωm), (2) a mushy dacitic magma reservoir beneath the caldera center at depths of 3–15 km (~ 500 km ³ , < 10 Ωm), and (3) a deeper basaltic magma reservoir to the west at depths of 15–30 km (~ 4500 km ³ , < 70 Ωm). The active volcanoes, deformation sources, and earthquake hypocenters are located above or near the conductor edges (2), suggesting that magmatic fluids from the deeper western source (3) preferentially ascend along the column edges. A distinctive feature of the caldera is the flattened upper boundary of conductor (2), which is associated with sill-shaped ground inflation. This geometry may indicate the potential to store large volume of mushy magma, which could become eruptible if magma is directly supplied from greater depths. This study provides new insights into the magma plumbing system beneath the Akan Caldera and enhances our understanding of the mechanisms underlying its volcanic activity.
  
  Graphical abstract
• Shallow thermal activity of Tokachidake Volcano (Japan) investigated through repeated drone-borne magnetic surveys
  Toshiaki Hokari; Ryo Tanaka; Takeshi Hashimoto; Takao Koyama
  Earth, Planets and Space, Springer Science and Business Media LLC, 13 Mar. 2026, [Peer-reviewed], [International Magazine]
  English, Scientific journal, Abstract
  
  In recent years, new geothermal anomalies have been detected on the northwestern slope of the 62-II crater near the summit of Tokachidake Volcano, Hokkaido, Japan. These surface manifestations imply the formation of new shallow subsurface pathways for hydrothermal fluids, accompanied by localized heating and progressive hydrothermal alteration along these pathways. Because hydrothermal alteration can weaken volcanic rocks and contribute to sector collapse, identifying the distribution of alteration and the associated temperature changes within the edifice is crucial for assessing potential collapse hazards. This study aimed to visualize the shallow thermal activity beneath Tokachidake Volcano using drone-borne magnetic surveys. Magnetic surveying provides insight into subsurface temperature changes and the extent of hydrothermal alteration. In particular, aeromagnetic surveys enable the efficient investigation of shallow volcanic thermal activity without terrain-related access limitations. We conducted drone-borne magnetic surveys in 2023, 2024, and 2025 to acquire geomagnetic field data around the geothermal anomalies at a constant clearance above the ground surface. From these datasets, we derived static magnetic anomalies that reflect the effects of topographic relief and subsurface heterogeneity, as well as their temporal differences. Three-dimensional inversion was then applied to estimate the distribution of subsurface magnetization intensity and its temporal variations. Static magnetization models revealed a columnar low-magnetization zone directly beneath the 62-II crater, representing the heated and hydrothermally altered regions surrounding the fumarolic conduit. Temporal magnetization variations revealed a remagnetized zone beneath the 62-II crater and a demagnetized zone beneath the geothermal anomalies, indicating the reorganization of shallow heat transfer associated with the development of new hydrothermal fluid pathways. The demagnetized zone beneath the Maetokachi slope suggests the presence of hydrothermal fluid pathways within the slope interior, where progressive alteration likely weakens the volcanic rocks and reduces slope stability. These findings provide new insights into the evolution of the shallow hydrothermal system of Tokachidake Volcano. The active redistribution of heat and fluids within the edifice appears to contribute to the internal weakening of the Maetokachi slope, potentially increasing the likelihood of future sector collapse. Continued aeromagnetic monitoring combined with hydrothermal and slope-stability modeling will be essential for effective hazard assessment.
  
  Graphical Abstract
• Numerical Simulation on the Electrical Conductivity of Ternary Mixtures Containing NaCl Solution, Quartz, and Smectite
  K. Aoyama; T. Hashimoto
  Journal of Geophysical Research: Solid Earth, 129, 11, American Geophysical Union (AGU), 29 Oct. 2024, [Peer-reviewed], [International Magazine]
  English, Scientific journal, Abstract
  
  While the electrical conductivity of smectite‐rich rocks is high, previous studies have only partially revealed its dependence on temperature, salinity, and porosity. This knowledge gap mainly arises from challenges in controlling various experimental conditions when measuring the conductivity of real smectite‐bearing rock samples and quantifying the smectite content. To mimic conductivity measurements under ideal conditions, this study aimed to develop a simulator capable of accurately configuring the conditions to predict the direct‐current conductivity of saturated rocks composed of an aqueous NaCl solution, quartz, and smectite under various temperatures (20°C–200°C), salinities (10⁻⁴–5 mol kg⁻¹), porosities (0–1), and smectite fractions (0–1). The simulator reproduced the experimental conductivity measurements from drilled core samples by giving the anisotropy of those components' distribution. In addition, simulations with randomly assigned components revealed that when rocks contain abundant smectite, the bulk conductivity partially decreases with increasing NaCl solution's salinity or volume fraction. These negative slopes were approximated using empirical equations derived from previous studies. Percolation analysis further revealed that when the components are randomly assigned, conductive paths begin to form between the ends of the modeled sample once the sum of the volume fraction of bulk pore and smectite reaches 0.1.
• The inclined conductive column effect: a new simple model for magnetotelluric anomalous phases
  Tomohiro Inoue; Takeshi Hashimoto
  Geophysical Journal International, 238, 3, 1825, 1839, Oxford University Press (OUP), 08 Jul. 2024, [Peer-reviewed]
  English, Scientific journal, SUMMARY
  
  Magnetotelluric data are sometimes accompanied by ‘anomalous’ impedance phases ($\phi $xy and $\phi $yx) in the off-diagonal components deviating from the first (0° &lt; $\phi $xy &lt; 90°) or third (−180° &lt; $\phi $yx &lt; −90°) quadrant, especially in long-period bands. This phenomenon is called the phases out-of-quadrant (POQ). The POQ poses a challenge in magnetotelluric modelling because simple 1-D or 2-D models cannot explain it. Previous studies have reported that strong inhomogeneity, anisotropy, or particular 3-D structures, such as the L-shaped or cross-shaped conductors, could explain the POQ. Aside from these models, we have discovered that a slanted columnar conductor also generates the POQ. Our systematic investigation through the synthetic forward modelling of an inclined conductive column with a varying geometry showed that the inclination angle and the column length may affect the POQ appearance. We investigated herein the behaviour of the electric currents around the inclined conductive column embedded in a resistive half-space. We found that the induced electric field in the region with the POQ tends to point in the opposite direction to the surrounding vectors. This result can reasonably explain the inverted phase in long-period bands. Furthermore, we confirmed that current is sucked into one end of the column, but discharged from the other end, suggesting that the column works as a current channel. The localized reverse vectors are associated with the current channelling along the inclined conductor, which generates the POQ. A volcanic conduit within a resistive host rock is one of the typical field examples of such an inclined channel. Our study suggests that the POQ is a helpful clue in imaging the geometry of a volcanic magma plumbing system through magnetotelluric surveys.
• Post-Eruptive Persistent Cooling Beneath the Summit Crater of Usu Volcano as Revealed by Magnetic Repeat Surveys
  Takeshi Hashimoto
  Journal of Disaster Research, 17, 5, 630, 638, Fuji Technology Press Ltd., 01 Aug. 2022, [Peer-reviewed], [Lead author]
  English, Scientific journal, Remarkable and continuous geomagnetic field change, suggesting remagnetization at a shallow depth, was detected through repeated geomagnetic field observation of the summit area of Mt. Usu Volcano from 2008 to 2021. Long-term cooling of the remnant magma, that intruded during the 1977–82 eruption, was considered responsible for the remagnetization. A magnetic dipole parallel to the present geomagnetic field well reproduced the observation. The modeled source was located near the Ginnuma crater on the south side of the previously inferred intrusive body beneath the Usu-Shinzan cryptodome. Meanwhile, no magnetic source was detected on the other side of the intrusion, implying asymmetric heat transport paths around the intrusion. Considering previous studies on seismicity, geodetic modeling, and resistivity structure, the magnetic source region is plausibly a high permeability zone through which heat from the intruded magma has been efficiently transported. In other words, the source region can be a key monitoring target for future eruptions as it may be linked to the subsurface magma system.
• A broadband magnetotelluric survey for Mt. Meakandake volcano with special attention to the unrest during 2016–2017
  Inoue, T; Hashimoto, T; Tanaka, R; Yamaya, Y
  Earth, Planets and Space, 74, 114, Jul. 2022, [Peer-reviewed]
  English, Scientific journal
• Magnetotelluric survey and three-dimensional resistivity structure in and around the Niseko area, southwestern Hokkaido
  Tamura, M; Oka, D; Okazaki, N; Suzuki, K; Hashimoto, T; Mogi, T
  Geothermics, 105, 102496, 102496, Elsevier BV, Jun. 2022, [Peer-reviewed]
  English, Scientific journal
• Monitoring of volcanic activity based on geomagnetic field observation
  Takeshi Hashimoto
  Bulletin of the volcanological society of Japan, 67, 4, 489, 500, 2022, [Peer-reviewed], [Lead author, Last author, Corresponding author]
  Japanese, Scientific journal
• Utilizing Thermal Demagnetization Events to Evaluate Volcanic Unrest and the Prospects for Eruption Forecasting
  Takeshi Hashimoto
  Journal of Geography, 130, 6, 771, 781, Dec. 2021, [Peer-reviewed], [Lead author, Corresponding author]
  Japanese, Scientific journal
• Three-dimensional inversion of audio-magnetotelluric data acquired from the crater area of Mt. Tokachidake, Japan
  Tanaka R; Yamaya Y; Tamura M; Hashimoto T; Okazaki N; Takahashi R; Mogi T
  Earth, Planets and Space, 73, 1, 172, Springer Science and Business Media LLC, Aug. 2021, [Peer-reviewed]
  English, Scientific journal, Abstract
  
  Subvolcanic hydrothermal systems can lead to hydrothermal eruptions as well as unrest phenomena without an eruptive event. Historical eruptions and recent unrest events, including ground inflation, demagnetization, and a gradual decrease in the plume height, at Mt. Tokachidake, central Hokkaido, Japan, are related to such a subvolcanic hydrothermal system. This study investigates the three-dimensional (3-D) resistivity structure of Mt. Tokachidake to image its subvolcanic hydrothermal system. A 3-D inversion of the magnetotelluric data, acquired at 22 sites around the crater area, was performed while accounting for the topography. Our resistivity model was characterized by a high-resistivity layer at a shallow depth (50–100 m) and two conductors near the active crater and dormant crater. The high-resistivity layer was interpreted to be composed of dense lava, which acts as a caprock surrounding the conductor. The high conductivity beneath the active crater can be explained by the presence of hydrothermal fluid in fractured or leached zones within the low-permeability lava layer, as the sources of ground inflation and demagnetization were identified within the conductive zone immediately beneath the resistive layer. The resistivity structure was used to estimate the volume of hydrothermal fluid within the pore space. The minimum volume of hydrothermal fluid beneath the active crater that can explain the resistivity structure was estimated to be 3 × 10⁶ m³. This estimate is comparable to the water volume that was associated with the long runout and highly fluidized lahar in 1926. The resistivity structure and volume of hydrothermal fluid presented in this study can be used as a reference for further numerical simulations, which aim to reveal the mechanisms of recent unrest events and assess the risk of hazards, such as lahar.
• Magmatic–hydrothermal system of Aso Volcano, Japan, inferred from electrical resistivity structures
  Matsushima N; Utsugi M; Takakura S; Yamasaki T; Hata M; Hashimoto T; Uyeshima M
  Earth Planets and Space, 72, 1, 57, 07 May 2020, [Peer-reviewed], [International Magazine]
  English, Scientific journal
• Significance of Electromagnetic Surveys at Active Volcanoes: Toward Evaluating the Imminence of Wet Eruptions
  Hashimoto T; Kanda W; Morita Y; Hayakawa M; Tanaka R; Aoyama H; Uyeshima M
  Journal of Disaster Research, 14, 5, 580, 591, Jun. 2019, [Peer-reviewed]
  English, Scientific journal
• On the Source Characteristics of Demagnetization and Ground Deformation Associated with Non-magmatic Activity
  Hashimoto T; Utsugi M; Ohkura T; Kanda W; Terada A; Miura S; Iguchi M
  Bull. Volcanol. Soc. Japan, 64, 2, 103, 119, Apr. 2019, [Peer-reviewed], [Lead author]
  Japanese
• Magnetotelluric survey on the northern foot of Meakandake volcano (Preliminary report)
  Inoue T; Hashimoto T
  Geophys. Bull. Hokkaido University, 82, 82, 25, 38, Mar. 2019
  Japanese
• Contention between supply of hydrothermal fluid and conduit obstruction: inferences from numerical simulations
  Ryo Tanaka; Takeshi Hashimoto; Nobuo Matsushima; Tsuneo Ishido
  Earth, Planets and Space, 70, 1, 72, Springer Berlin Heidelberg, 01 Dec. 2018, [Peer-reviewed]
  English, Scientific journal
• Three‐Dimensional Electrical Resistivity Modeling to Elucidate the Crustal Magma Supply System Beneath Aso Caldera, Japan
  Hata M; Matsushima N; Takakura S; Utsugi M; Hashimoto T; Uyeshima M
  Journal of Geophysical Research, Solid Earth, 123, 8, 6334, 6346, Jul. 2018, [Peer-reviewed]
  English, Scientific journal
• Three‐Dimensional Electrical Resistivity Distribution Beneath the Beppu–Shimabara Graben With a Focus on Aso Caldera, Southwest Japan Subduction Zone
  Hata M; Uyeshima M; Tanaka Y; Hashimoto T; Oshiman N; Yoshimura R
  Journal of Geophysical Reserach, Solid Earth, 123, 8, 6397, 6410, Jul. 2018, [Peer-reviewed]
  English, Scientific journal
• Volcanic smoke reduction in visible and thermal infrared imagery
  Hashimoto T; Terada A; Tanaka R
  Earth Planets Space, 70, 109, Jul. 2018, [Peer-reviewed], [Invited]
  English, Scientific journal
• Water sampling using a drone at Yugama crater lake, Kusatsu‑Shirane volcano, Japan
  Terada A; Morita Y; Hashimoto T; Mori T; Ohba T; Yaguchi M; Kanda W
  Earth Planets Space, 70, 64, Apr. 2018, [Peer-reviewed]
  English, Scientific journal
• Importance of multi-disciplinary monitoring during inter-eruptive periods -A case study from Mt. Tarumae-
  Hashimoto T; Aoyama H; Koyama H; Morii A; Mishima W; Ogino T; Takahashi R; Okazaki N
  Monthly Chikyu, 40, 3, 163, 169, 2018
  Japanese
• Variety and sustainability of volcanic lakes: Response to subaqueous thermal activity predicted by a numerical model
  Akihiko Terada; Takeshi Hashimoto
  JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, 122, 8, 6108, 6130, Aug. 2017, [Peer-reviewed]
  English, Scientific journal
• Magnetotelluric survey on Tokachidake volcano -wideband MT survey across the volcano and AMT survey around the crater area-
  Tamura M; Okazaki N; Takahashi R; Hashimoto T; Okuda M; Sugano K; Hayakawa M; Takata M; Hashimoto M; Mishima W
  Conductivity Anomaly Research, 16, 23, Mar. 2017
  Japanese
• Three-dimensional resistivity structure of Asama Volcano revealed by data-space magnetotelluric inversion using unstructured tetrahedral elements
  Yoshiya Usui; Yasuo Ogawa; Koki Aizawa; Wataru Kanda; Takeshi Hashimoto; Takao Koyama; Yusuke Yamaya; Tsuneomi Kagiyama
  GEOPHYSICAL JOURNAL INTERNATIONAL, 208, 3, 1359, 1372, Mar. 2017, [Peer-reviewed]
  English, Scientific journal
• Permeability-control on volcanic hydrothermal system: case study for Mt. Tokachidake, Japan, based on numerical simulation and field observation
  Ryo Tanaka; Takeshi Hashimoto; Nobuo Matsushima; Tsuneo Ishido
  EARTH PLANETS AND SPACE, 69, Mar. 2017, [Peer-reviewed]
  English, Scientific journal
• Three-dimensional resistivity structure in Ishikari Lowland, Hokkaido, northeastern Japan-Implications to strain concentration mechanism
  Yusuke Yamaya; Toru Mogi; Ryo Honda; Hideaki Hase; Takeshi Hashimoto; Makoto Uyeshima
  GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS, 18, 2, 735, 754, Feb. 2017, [Peer-reviewed]
  English, Scientific journal
• A mechanism explaining appearances/disappearances of hot crater lakes:: Evaluations of volcanic activity of Aso volcano based on observations of Yudamari crater lake
  Terada Akihiko; Hashimoto Takeshi
  PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN, 2017, 48, 48, The Volcanological Society of Japan, 2017
  Japanese
• 3-D electrical resistivity model beneath Aso caldera for clarifying magmatism in the lower crust (2)
  HATA Maki; MATSUSHIMA Nobuo; TAKAKURA Shinichi; UTSUGI Mitsuru; HASHIMOTO Takeshi; UYESHIMA Makoto
  PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN, 2017, 47, 47, The Volcanological Society of Japan, 2017
  Japanese
• 3-D electrical resistivity structure based on geomagnetic transfer functions exploring the features of arc magmatism beneath Kyushu, Southwest Japan Arc
  Maki Hata; Makoto Uyeshima; Shun Handa; Masashi Shimoizumi; Yoshikazu Tanaka; Takeshi Hashimoto; Tsuneomi Kagiyama; Hisashi Utada; Hiroshi Munekane; Masahiro Ichiki; Kiyoshi Fuji-ta
  JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, 122, 1, 172, 190, Jan. 2017, [Peer-reviewed]
  English, Scientific journal
• Seismicity controlled by resistivity structure: the 2016 Kumamoto earthquakes, Kyushu Island, Japan
  Koki Aizawa; Hisafumi Asaue; Katsuaki Koike; Shinichi Takakura; Mitsuru Utsugi; Hiroyuki Inoue; Ryokei Yoshimura; Ken'ichi Yamazaki; Shintaro Komatsu; Makoto Uyeshima; Takao Koyama; Wataru Kanda; Taro Shiotani; Nobuo Matsushima; Maki Hata; Tohru Yoshinaga; Kazunari Uchida; Yuko Tsukashima; Azusa Shito; Shiori Fujita; Asuma Wakabayashi; Kaori Tsukamoto; Takeshi Matsushima; Masahiro Miyazaki; Kentaro Kondo; Kanade Takashima; Takeshi Hashimoto; Makoto Tamura; Satoshi Matsumoto; Yusuke Yamashita; Manami Nakamoto; Hiroshi Shimizu
  EARTH PLANETS AND SPACE, 69, Jan. 2017, [Peer-reviewed]
  English, Scientific journal
• Special issue "The phreatic eruption of Mt. Ontake volcano in 2014"
  Koshun Yamaoka; Nobuo Geshi; Takeshi Hashimoto; S. E. Ingebritsen; Teruki Oikawa
  EARTH PLANETS AND SPACE, 68, Nov. 2016, [Peer-reviewed]
  English, Scientific journal
• Crustal magma pathway beneath Aso caldera inferred from three-dimensional electrical resistivity structure
  Maki Hata; Shinichi Takakura; Nobuo Matsushima; Takeshi Hashimoto; Mitsuru Utsugi
  GEOPHYSICAL RESEARCH LETTERS, 43, 20, 10720, 10727, Oct. 2016, [Peer-reviewed]
  English, Scientific journal
• Crustal structure and fluid distribution beneath the southern part of the Hidaka collision zone revealed by 3-D electrical resistivity modeling
  Hiroshi Ichihara; Toru Mogi; Kengo Tanimoto; Yusuke Yamaya; Takeshi Hashimoto; Makoto Uyeshima; Yasuo Ogawa
  GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS, 17, 4, 1480, 1491, Apr. 2016, [Peer-reviewed]
  English, Scientific journal
• Preliminary result of MT survey at Usu volcano and Tokachidake volcano, Hokkaido
  Tamura M; Okazaki N; Takahashi R; Oka D; Akita F; Okuda M; Hashimoto T; Sugano K; Mogi T; Yamaya Y; Fujimatsu J; Nagayama H; Michishita T
  Conductivity Anomaly Research, 84, 89, Mar. 2016
  Japanese
• Magnetic total field changes and thermal activity around Nakamachineshiri crater, Meakandake
  Tanaka R; Hashimoto T; Suzuki A
  Geophysical Bulletin of Hokkaido University, 79, 15, 23, 北海道大学大学院理学研究院, Mar. 2016
  Japanese, We performed measurements of the magnetic total intensity at Nakamachineshiri crater of Meakandake volcano, eastern Hokkaido, in 2013, 2014 and 2015. Comparing the three campaigns, we found small but systematic magnetic changes suggesting demagnetization at the shallow subsurface of the crater during 2014-2015. We estimated the best-fit demagnetized source as a sphere with magnetic moment of 2×106 Am2 at a depth of 250 m (960 m a.s.l) beneath the crater. We then considered it was brought by thermal demagnetization, and made an order estimation of the heating rate at the source by assuming a simplistic temperature-magnetization relationship. In addition, we assessed the surface heat loss due to discharging fumarolic gas, evaporation and radiation from hot ponds, and geothermal anomalies. Total amount of the surface heat discharge rate was estimated to be in a range from a few to 10-odd MW. This might be comparable or one-order smaller than the heating rate based on the crude estimation from magnetic measurements.
• Volcanic plume measurements using a UAV for the 2014 Mt. Ontake eruption
  Toshiya Mori; Takeshi Hashimoto; Akihiko Terada; Mitsuhiro Yoshimoto; Ryunosuke Kazahaya; Hiroshi Shinohara; Ryo Tanaka
  EARTH PLANETS AND SPACE, 68, Mar. 2016, [Peer-reviewed]
  English, Scientific journal
• Crater lake energy and mass balance
  Tony Hurst; Takeshi Hashimoto; Akihiko Terada
  Volcanic Lakes, 307, 321, Springer Berlin Heidelberg, 01 Jan. 2015, [Peer-reviewed]
  English, In book
• Volcanomagnetic Effects and Phreatic Eruptions
  Hashimoto T
  Conductivity Anomaly Research, 75, 81, 2015
  Japanese
• Electrical Resistivity Structure Beneath the Kyushu District by Using Geomagnetic Transfer Functions
  Hata, M; M. Uyeshima; S. Handa; M. Shimoizumi; Y. Tanaka; T. Hashimoto; T. Kagiyama; H. Utada; H. Munekane; M. Ichiki; K. Fujita
  Conductivity Anomaly Research, 18, 20, 2015
  Japanese
• Geomagnetic secular changes in eastern Hokkaido (Part 2)
  Mishima, W; T. Hashimoto; T. Mogi; T. Moriyama; J. Ohgi; K. Morinaga
  Geophysical Bulletin of Hokkaido University, 78, 78, 69, 82, 北海道大学大学院理学研究院, 2015
  Japanese, Regional to subregional-scale anomaly in the rate of geomagnetic secular changes have been observed in eastern Hokkaido. The origin of such anomalous changes has long been discussed. Based on the total field records, some previous studies suspected the piezomagnetic effect is due to stress loading accompanying subducting plate motion as the major cause. We started three-component absolute measurements at eight continuous magnetic stations in 2009, aiming at revealing the mechanisms of the anomaly. This study reports the results of the absolute measurements up to 2014, as well as the continuous total field records. Although we have performed the absolute measurements only twice or three times at each station, it is readily recognized that the rate of secular change with respect to Memambetsu in horizontal and vertical components differs from site to site. Steeper trends near the southern coast are the characteristics similar to the case in the total field. Declination looks more complicated, presumably showing clockwise rotation in the northern area, while anti-clockwise in the south. Considering the compressional stress region of eastern Hokkaido and existence of highly-magnetized rocks in the coastal area, the piezomagnetic effect is still a candidate for these spatiotemporal variations. Based on the available dataset, we conclude that the anomaly in the total field is not brought by the so-called orientation effect, and that there must be such real changes of tens to hundred km scale, whatever the cause is. It should be the next step in the future works to verify the piezomagnetic hypothesis by comparing the three-component rate of change through a numerical simulation.
• Aeromagnetic survey using an unmanned autonomous helicopter over Tarumae Volcano, northern Japan
  Takeshi Hashimoto; Takao Koyama; Takayuki Kaneko; Takao Ohminato; Takatoshi Yanagisawa; Mitsuhiro Yoshimoto; Eiichi Suzuki
  EXPLORATION GEOPHYSICS, 45, 1, 37, 42, Mar. 2014, [Peer-reviewed]
  English, Scientific journal
• Aeromagnetic repeat surveys over Tarumae volcano
  Hashimoto, T; T. Koyama; T. Ohminato; T. Kaneko; T. Yanagisawa; M. Yoshimoto; E. Suzuki
  Conductivity Anomaly Research, 92, 99, CA研究グループ, 2014
  Japanese
• Three-dimensional resistivity structure and magma plumbing system of the Kirishima Volcanoes as inferred from broadband magnetotelluric data
  Koki Aizawa; Takao Koyama; Hideaki Hase; Makoto Uyeshima; Wataru Kanda; Mitsuru Utsugi; Ryokei Yoshimura; Yusuke Yamaya; Takeshi Hashimoto; Ken'ichi Yamazaki; Shintaro Komatsu; Atsushi Watanabe; Koji Miyakawa; Yasuo Ogawa
  JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, 119, 1, 198, 215, Jan. 2014, [Peer-reviewed]
  English, Scientific journal
• A large hydrothermal reservoir beneath Taal Volcano (Philippines) revealed by magnetotelluric resistivity survey: 2D resistivity modeling
  Y. Yamaya; P. K. B. Alanis; A. Takeuchi; J. M. Cordon; T. Mogi; T. Hashimoto; Y. Sasai; T. Nagao
  BULLETIN OF VOLCANOLOGY, 75, 7, Jul. 2013, [Peer-reviewed]
  English, Scientific journal
• Three-dimensional shallow resistivity structure of Sakurajima volcano
  Kanda W; Ogawa Y; Takakura S; Koyama T; Hashimoto T; Komori S; Sonoda T; Sato I; Inoue N; Utsugi M
  Conductivity Anomaly Research, 139, 144, CA研究グループ, 2013
  Japanese
• Aeromagnetic surveys over Tarumae volcano using an unmanned autonomous helicopter
  Hashimoto, T; T. Koyama; T. Kaneko; T. Ohminato; T. Yanagisawa; M. Yoshimoto; E. Suzuki
  Conductivity Anomaly Research, 81, 87, CA研究グループ, 2013
  Japanese
• Magnetotelluric and temperature monitoring after the 2011 sub-Plinian eruptions of Shinmoe-dake volcano
  Koki Aizawa; Takao Koyama; Makoto Uyeshima; Hideaki Hase; Takeshi Hashimoto; Wataru Kanda; Ryokei Yoshimura; Mitsuru Utsugi; Yasuo Ogawa; Ken'ichi Yamazaki
  EARTH PLANETS AND SPACE, 65, 6, 539, 550, 2013, [Peer-reviewed]
  English, Scientific journal
• Transition in eruption style during the 2011 eruption of Shinmoe-dake, in the Kirishima volcanic group: Implications from a steady conduit flow model
  Ryo Tanaka; Takeshi Hashimoto
  Earth, Planets and Space, 65, 6, 645, 655, Springer Berlin, 2013, [Peer-reviewed]
  English, Scientific journal
• Shallow Resistivity Structure of Sakurajima Volcano Revealed by Audio-frequency Magnetotellurics
  Kanda, W; T. Yamazaki; Y. Ogawa; T. Hashimoto; K. Aizawa; S. Takakura; T. Koyama; K. Yamada; T. Kobayashi; S. Komori
  Bull. Volcanol. Soc. Japan, 58, 1, 251, 267, The Volcanological Society of Japan, 2013, [Peer-reviewed]
  English, Scientific journal, An audio-frequency magnetotelluric (AMT) survey was conducted at the foot of Sakurajima volcano in November 2007. This survey was carried out within the framework of the 7th National Project for Prediction of Volcano Eruptions. The main objective was to clarify the shallow layers of Sakurajima volcano for better understanding of the volcanic activity. We measured electromagnetic fields at frequencies from 1 to 10400 Hz at 27 locations along only three lines set on the northern, western, and southeastern flanks of the volcano. The three profiles enclosed the summit area where access is prohibited because of frequent explosive vulcanian eruptions. The data quality was generally considered to be good at frequencies higher than 2 Hz. Two-dimensional and three-dimensional (3-D) modeling approaches were applied to the data. As a result of 3-D modeling, we obtained the following features in the resistivity model. The surface layer showed a high resistivity from several hundreds to thousands of ohm-meters and corresponded to the lava. This surface layer covered a highly conductive layer with a resistivity of less than tens of ohm-meters, interpreted as containing seawater or groundwater. However, the basement structure was not clearly detected, except for in an area of northern Sakurajima. The first lava layer was distributed thickly in northern and western parts of Sakurajima, and the boundary between the first and second layers was typically located at around sea level. The conductive second layer was found at deeper levels beneath areas such as the Haruta-yama lava dome and the Nabe-yama pumice cone. This depression of the low resistivity layer is probably caused by the fracture zone associated with previous eruptions, which is formed above the conductive layer. In the proximity of Hikino-hira lava dome and the Taisho crater, the second conductive layer was found at a depth shallower than sea level, suggesting that a hydrothermal system has developed underneath this area. In contrast, elevation of the second layer was not seen on the side of Taisho crater located nearest to the edge of Nabe-yama, implying that a heat source is not present beneath the eastern foot of Sakurajima.
• A water flow model of the active crater lake at Aso volcano, Japan: fluctuations of magmatic gas and groundwater fluxes from the underlying hydrothermal system
  Akihiko Terada; Takeshi Hashimoto; Tsuneomi Kagiyama
  BULLETIN OF VOLCANOLOGY, 74, 3, 641, 655, Apr. 2012, [Peer-reviewed]
  English, Scientific journal
• Geomagnetic secular changes in eastern Hokkaido
  Hashimoto, T; T. Mogi; M. Nishimura; S. Arita; J. Shimizu; T. I; Y. Minamoto; S. Nagamachi
  Geophysical Bulletin of Hokkaido University, 75, 75, 117, 132, 北海道大学大学院理学研究院自然史科学部門（地球物理学）, Mar. 2012
  Japanese, Localized geomagnetic secular changes have been reported in the eastern Hokkaido, previouslyby repeat surveys, and more recently, by continuous recording. Some previous studies discussthe piezo-magnetic field due to stress accumulation by plate subduction. To elucidate the natureof such "anomalous" secular changes in the total field, we started geomagnetic three-componentabsolute measurements. Firstly, we estimated the so-called orientation effect which may becontained in the simple differential total field, by using the results of the absolute measurements.At some stations this effect has been found to be non-negligible. While correcting the orientation effect, we assessed an effect of global-scale secular changesby using the IGRF-11 model. This effect contributes much to regional-scale secular changes inthe eastern Hokkaido. As a result, considerable part of the observed differential total field canbe explained by this component. Then, residuals which deviated from the global secular fieldare obtained, which showed relatively good agreement with the predicted piezo-magnetic field. However, it is still uncertain that the residual field is significant or not, as well as its origin. Our analysis has also revealed an "anomalous" decreasing trend in the total field in the late90s at NIB station which is located at the eastern side of Kussharo caldera. We speculate thatthis anomalous magnetic change may have some relation to the elevated signature of volcanicunrest at Atosanupuri where seismic swarm was followed by significant ground deformation in themid 90s.
• Aeromagnetic survey using an unmanned autonomous helicopter over Tarumae Volcano
  Hashimoto, T; T. Koyama; T. Kaneko; T. Ohminato; M. Yoshimoto; E. Suzuki; T. Yanagisawa
  Geophysical Bulletin of Hokkaido University, 75, 145, 159, Mar. 2012
  Japanese
• Aeromagnetic survey using an unmanned autonomous helicopter over Tarumae Volcano
  Takeshi Hashimoto; Takao Koyama; Takayuki Kaneko; Takao Ohminato; Mitsuhiro Yoshimoto; Eiichi Suzuki; Takatoshi Yanagisawa
  Journal of the Hokkaido University, Faculty of Science, Series VII: Geophysics, 75, 145, 159, 2012, [Peer-reviewed]
• A low-cost SO_2 Imager with the Use of Digital Cameras of Consumer Use,
  Hashimoto, T; A. Terada; M. Ejiri; T. Nakamura; M. Abo
  Bull. Volcanol. Soc. Japan, 57, 4, 219, 225, 2012, [Peer-reviewed]
  Japanese, Scientific journal
• Airborne electromagnetic and magnetic surveys for long tunnel construction design
  Kenji Okazaki; Toru Mogi; Mitsuru Utsugi; Yoshihiko Ito; Hideki Kunishima; Takashi Yamazaki; Yukitsugu Takahashi; Takeshi Hashimoto; Yusuke Ymamaya; Hisatoshi Ito; Hideshi Kaieda; Kazuhiro Tsukuda; Youichi Yuuki; Akira Jomori
  PHYSICS AND CHEMISTRY OF THE EARTH, 36, 16, 1237, 1246, 2011, [Peer-reviewed]
  English, Scientific journal
• Temporal magnetic changes possibly due to cooling magmas as revealed by repeat helicopter-borne magnetic surveys over an active volcano
  Hashimoto, T; M. Utsugi; T. Nakatsuka; S. Okuma; T. Koyama; W. Kanda
  Proceedings of the 10th SEGJ International Symposium, Kyoto, 276, 279, 2011, [Peer-reviewed]
  English, International conference proceedings
• B2-13 Resistivity Structure beneath the Taal volcano, Philippines revealed by magnetotelluric method
  Yamaya Yusuke; Sasai Yoichi; Takeuchi Akihiro; Mogi Toru; Alanis Paul; Cordon Jr Juan; Hashimoto Takeshi; Nagao Toshiyasu
  PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN, 2011, 90, 90, The Volcanological Society of Japan, 2011
  Japanese
• A1-22 Aeromagnetic survey at Shinmoe-dake using unmanned autonomous helicopter
  Koyama Takao; Kaneko Takayuki; Ohminato Takao; Watanabe Atsushi; Takeo Minoru; Yanagisawa Takatoshi; Hashimoto Takeshi; Honda Yoshiaki
  PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN, 2011, 22, 22, The Volcanological Society of Japan, 2011
  Japanese
• Electromagnetic monitoring of Taal volcano: SATREPS-Project 2010-2014
  Nagao, T; A. Takeuchi; Y. Sasai; Y. Yamaya; T. Hashimoto; T. Mogi; Y. Tanaka; P.K. Alanis; J.M. Cordon Jr; J. Sabit; J.S. Sincioco
  Conductivity Anomaly Research, 2011, 20, 20, 2011
  Japanese
• Magnetic anomaly change of Usu Volcano 2000-2010 detected by repeated aeromagnetic surveys with a study on the accuracy of 2000 survey altitude data
  Nakatsuka, T; S. Okuma; Joint Group for; Usu Volcano Airborne Magnetic Survey
  Conductivity Anomaly Research, 2011, 37, 43, CA研究グループ, 2011
  Japanese
• A heating process of Kuchi-erabu-jima volcano, Japan, as inferred from geomagnetic field variations and electrical structure
  Wataru Kanda; Mitsuru Utsugi; Yoshikazu Tanaka; Takeshi Hashimoto; Ikuko Fujii; Toshiaki Hasenaka; Nobuaki Shigeno
  JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH, 189, 1-2, 158, 171, Jan. 2010, [Peer-reviewed]
  English, Scientific journal
• Hydrothermal system beneath the crater of Tarumai volcano, Japan: 3-D resistivity structure revealed using audio-magnetotellurics and induction vector
  Yusuke Yamaya; Toru Mogi; Takeshi Hashimoto; Hiroshi Ichihara
  JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH, 187, 3-4, 193, 202, Nov. 2009, [Peer-reviewed]
  English, Scientific journal
• Detection of aeromagnetic anomaly change associated with volcanic activity: An application of the generalized mis-tie control method
  Tadashi Nakatsuka; Mitsuru Utsugi; Shigeo Okuma; Yoshikazu Tanaka; Takeshi Hashimoto
  TECTONOPHYSICS, 478, 1-2, 3, 18, Nov. 2009, [Peer-reviewed]
  English, Scientific journal
• Inter-eruptive volcanism at Usu volcano: Micro-earthquakes and dome subsidence
  Hiroshi Aoyama; Shin'ya Onizawa; Tomokadu Kobayashi; Takeshi Tameguri; Takeshi Hashimoto; Hiromitsu Oshima; Hitoshi Y. Mori
  JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH, 187, 3-4, 203, 217, Nov. 2009, [Peer-reviewed]
  English, Scientific journal
• Hydrothermal System beneath Usu Volcano Inferred from Self-potential Survey and Simulation
  Hideaki Hase; Takeshi Hashimoto; Yasunori Nishida; Mtsuru Ursugi; Hiroyuki Inoue; Mzue Saba
  Journal of the Geothermal Research Society of Japan, 31, 1, 27, 37, 2009, [Peer-reviewed]
  English, Scientific journal
• A preparation zone for volcanic explosions beneath Naka-dake crater, Aso volcano, as inferred from magnetotelluric surveys
  Wataru Kanda; Yoshikazu Tanaka; Mitsuru Utsugi; Shinichi Takakura; Takeshi Hashimoto; Hiroyuki Inoue
  JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH, 178, 1, 32, 45, Nov. 2008, [Peer-reviewed]
  English, Scientific journal
• The role of thermal viscous remanent magnetisation (TVRM) in magnetic changes associated with volcanic eruptions: Insights from the 2000 eruption of Mt Usu, Japan
  T. Hashimoto; T. Hurst; A. Suzuki; T. Mogi; Y. Yamaya; M. Tamura
  JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH, 176, 4, 610, 616, Oct. 2008, [Peer-reviewed]
  English, Scientific journal
• Resistivity structure of Unzen Volcano derived from time domain electromagnetic (TDEM) survey
  Wahyu Srigutomo; Tsuneomi Kagiyama; Wataru Kanda; Hiroshi Munekane; Takeshi Hashimoto; Yoshikazu Tanaka; Hisashi Utada; Mitsuru Utsugi
  JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH, 175, 1-2, 231, 240, Jul. 2008, [Peer-reviewed]
  English, Scientific journal
• Shallow resistivity structure of Asama Volcano and its implications for magma ascent process in the 2004 eruption
  Koki Aizawa; Yasuo Ogawa; Takeshi Hashimoto; Takao Koyama; Wataru Kanda; Yusuke Yamaya; Masaaki Mishina; Tsuneomi Kagiyama
  JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH, 173, 3-4, 165, 177, Jun. 2008, [Peer-reviewed]
  English, Scientific journal
• Numerical modeling of hydrothermal systems due to a magma intrusion
  佐波 瑞恵; 茂木 透; 西田 泰典; 橋本 武志; 田村 慎
  Geophysical bulletin of Hokkaido University, 71, 49, 59, 北海道大学大学院理学研究院自然史科学部門（地球物理学）, Mar. 2008
  Japanese, Cooling of intruded magma, development and decay of hydrothermal systems are investigated by model calculations for various combination of parameters such as hydraulic permeability of the intruded magma and its surroundings. Dependence of the pressure gradient on the hydrothermal systems is also investigated to inspect the effect of the potential flow of the groundwater along the topography. In the case that the horizontal pressure gradient is smaller than buoyancy, the hydrothermal system develops just above the intruded magma, while the greater pressure gradient as well as high permeability of surroundings carries the hydrothermal system to downstream. We applied these examinations to the newly formed Nishiyama geothermal field at the time of the 2000 Usu eruption. Numerical calculations considering the real topography in and around the Nishiyama geothermal field well reproduce the observed temporal variations of geothermal field appeared on the ground surface, assuming the in-situ hydraulic permeability of the intruded magma and the surroundings as l0－12～10－13m2 and 10－l0～10－11m2, respectively.
• Water, Heat and Chloride Balances of the Crater Lake at Aso Volcano, Japan
  Takeshi Saito; Shinji Ohsawa; Takeshi Hashimoto; Akihiko Terada; Shinyo Shikawa; Takahiro Ohkuea
  Journal of the Geothermal Research Society of Japan, 30, 2, 107, 120, 2008, [Peer-reviewed]
  English, Scientific journal
• Precise remote-monitoring technique of water volume and temperature of a crater lake in Aso volcano, Japan: implications for a sensitive window of a volcanic hydrothermal system
  Akihiko Terada; Takeshi Hashimoto; Tsuneomi Kagiyama; Hisashi Sasaki
  EARTH PLANETS AND SPACE, 60, 6, 705, 710, 2008, [Peer-reviewed]
  English, Scientific journal
• Time evolution of hydraulic and electrokinetic parameters around the Nojima fault, Japan, estimated by an electrokinetic method
  Hideki Murakami; Naoto Oshiman; Satoru Yamaguchi; Takeshi Hashimoto; Ryokei Yoshimura
  TECTONOPHYSICS, 443, 3-4, 200, 208, Oct. 2007, [Peer-reviewed]
  English, Scientific journal
• 有珠山の地殻変動予測に関する研究
  岡崎紀俊; 大津直; 廣瀬亘; 石丸聡; 田村慎; 川上源太郎; 田近淳; 高橋浩晃; 橋本武志; 茂木透; 笠原稔
  北海道立地質研究所調査研究報告(CD-ROM), 35, 150P,SUPPL 1P, 30 Mar. 2007
  Japanese
• Drag-out effect of piezomagnetic signals due to a borehole: the Mogi source as an example
  Yoichi Sasai; Malcom J. S. Johnston; Yoshikazu Tanaka; Robert Mueller; Takeshi Hashimoto; Mitsuru Utsugi; Shinya Sakanaka; Makoto Uyeshima; Jacques Zlotnicki; Paul Yvetot
  ANNALS OF GEOPHYSICS, 50, 1, 93, 104, Feb. 2007, [Peer-reviewed]
  English, Scientific journal
• Micro-earthquake activity at Usu volcano revealed by temporary dense observation
  Hiroshi Aoyama; Shin'ya Onizawa; Takeshi Tameguri; Atsuo Suzuki; Tokumitsu Maekawa; Hiromitsu Oshima; Hitoshi Mori; Takeshi Hashimoto; Toru Shiga; Hiroshi Koyama; Masaki Nakahashi; Akifumi Yoshikawa; Yoshirou Fukuyama
  Journal of the Hokkaido University, Faculty of Science, Series VII: Geophysics, 70, 107, 121, 2007
  Japanese, Scientific journal
• Geomagnetic changes due to doming - The 2000 eruption of Usu volcano
  Takeshi Hashimoto; Tohru Mogi; Yasunori Nishida; Masamitsu Takada; Atsuo Suzuki; Tokumitsu Maekawa; Hideyuki Satoh
  Journal of the Hokkaido University, Faculty of Science, Series VII: Geophysics, 70, 123, 135, 2007
  Japanese, Scientific journal
• Observation of water vapor with a portable raman lidar -continuous monitoring and field experiments over the forest and at the volcano-
  Nakamura, T; N. Sugimoto; T. Tsuda; M. Abo; T. Hashimoto; A. Terada
  Proceedings of the 23rd International Laser Radar Conference, 897, 900, 2006, [Peer-reviewed]
  English, Symposium
• 阿蘇中岳周辺の比抵抗構造
  神田 径; 田中 良和; 宇津木 充; 高倉 伸一; 橋本武志; 井上 寛之; 岡田靖章
  CA研究会2006年論文集, 86, 88, CA研究グループ, 2006
  Japanese
• 平成17年度浅間山電磁気構造探査の概要
  橋本武志; 茂木 透; 鈴木敦生; 山谷祐介; 三品正明; 中塚 正; 小山悦郎; 小山崇夫; 相澤広記; 平林順一; 松尾元広; 野上建治; 小川康雄; 氏原直人; 鍵山恒臣; 神田 径; 大久保綾子; 田中良和; 宇都智史; 宇津木 充
  CA研究会2006年論文集, 79, 80, 2006
  Japanese
• Local zero setting of thermoluminescence in milled quartz grains
  A.Takeuchi; H. Nagahama; T. Hashimoto
  11th International Conference on Luminescence and Electron Spin Resonance Dating (Cologne, Germany, July 24-29, 2005), Book of Abstracts, 180, Jul. 2005, [Peer-reviewed], [Invited]
  English, International conference proceedings
• Hydrothermal system beneath Mt. Fuji volcano inferred from magnetotellurics and electric self-potential
  K Aizawa; R Yoshimura; N Oshiman; K Yamazaki; T Uto; Y Ogawa; SB Tank; W Kanda; S Sakanaka; Y Furukawa; T Hashimoto; M Uyeshima; T Ogawa; Shiozaki, I; AW Hurst
  EARTH AND PLANETARY SCIENCE LETTERS, 235, 1-2, 343, 355, Jun. 2005, [Peer-reviewed]
  English, Scientific journal
• Hydrothermal system beneath Aso volcano as inferred from self-potential mapping and resistivity structure
  H Hase; T Hashimoto; S Sakanaka; W Kanda; Y Tanaka
  JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH, 143, 4, 259, 277, May 2005, [Peer-reviewed]
  English, Scientific journal
• Wide-band MT survey on Tarumai volcano, Hokkaido -2-D resistivity analysis
  Yusuke Yamaya; Takeshi Hashimoto; Toru Mogi; Atsuo Suzuki; Yasunori Nishida; Kengo Tanimoto; Hitoshi Mori; Akihiko Terada; Masaaki Mishina; Hideaki Hase
  Journal of the Hokkaido University, Faculty of Science, Series VII: Geophysics, 68, 127, 140, Mar. 2005
  Japanese, Scientific journal
• Electrical Resistivity Survey at the Western Part of Usu Summit Caldera : Subsurface Structure of Faults Developed at the 2000 Usu Volcano Eruption
  茂木 透; 橋本 武志
  Geophysical bulletin of Hokkaido University, 68, 233, 241, 北海道大学大学院理学研究科地球惑星科学専攻（地球物理学）, Mar. 2005
  Japanese
• Magma supply & emission system of Unzen Volcano deduced from resistivity structure
  Kagiyama, Tsuneomi; Srigutomo, Wahyu; Kanda, Wataru; Hashimoto, Takeshi; Tanaka; Yoshikazu; Ogawa; Tsutomu; Utsugi, Mitsuru
  Extended Abstract of international workshop on Unzen Scientific Drilling Project 2005, 41, 42, 2005
  English
• Magnetic field changes on White Island, New Zealand, and the value of magnetic changes for eruption forecasting
  AW Hurst; PC Rickerby; BJ Scott; T Hashimoto
  JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH, 136, 1-2, 53, 70, Aug. 2004, [Peer-reviewed]
  English, Scientific journal
• 空中磁気測量を用いた火山爆発場解明についての試み-空中磁気測量からの磁場時間変化検出の試み-
  宇津木 充; 田中 良和; 橋本 武志
  火山爆発のダイナミックス, 95, 101, 2004
  Scientific journal
• 空中磁気測量を用いた火山爆発場解明についての試み-空中磁気測量からの磁場時間変化検出の試み-
  宇津木 充; 田中 良和; 橋本 武志
  火山爆発のダイナミックス(平成15年度成果報告書), 95, 101, 2004
  Scientific journal
• zeta potential measurement of volcanic rocks from Aso caldera
  H Hase; T Ishido; S Takakura; T Hashimoto; K Sato; Y Tanaka
  GEOPHYSICAL RESEARCH LETTERS, 30, 23, Dec. 2003, [Peer-reviewed]
  English, Scientific journal
• Continuing deflation by fumaroles at Kuju Volcano, Japan
  M Nakaboh; H Ono; M Sako; Y Sudo; T Hashimoto; AW Hurst
  GEOPHYSICAL RESEARCH LETTERS, 30, 7, Apr. 2003, [Peer-reviewed]
  English, Scientific journal
• Zeta-Potential Experiments of Rocks in Kyushu Various Volcanoes
  HASE HIDEAKI; ISHIDO TSUNEO; HASHIMOTO TAKESHI; KANDA WATARU; SATO KEIKO
  京都大学防災研究所年報, 46B, 787-795, 795, Apr. 2003
  Japanese
• Resistivity structure of Unzen Volcano, Kyushu, Japan from time domain electromagnetic (TDEM) data and its implication to magma-ground water interaction
  Srigutomo, Wahyu; Kagiyama, Tsuneomi; Kanda, Wataru; Hashimoto, Takeshi; Munekane, Hiroshi; Tanaka, Yoshikazu; Utsugi, Mitsuru; Ohminato, Takao
  Abstracts of XXIII General Assembly of IUGG, Week A, 2003
  English
• Magnetic and electric field observations during the 2000 activity of Miyake-jima volcano, Central Japan
  Y Sasai; M Uyeshima; J Zlotnicki; H Utada; T Kagiyama; T Hashimoto; Y Takahashi
  EARTH AND PLANETARY SCIENCE LETTERS, 203, 2, 769, 777, Oct. 2002, [Peer-reviewed]
  English, Scientific journal
• Continuous depression by fumarolic activity at Iwoyama, Kuju Volcano, Kyushu, Japan
  Nakaboh, M; Ono, H; Sako, M; Sudo, Y; Hashimoto, T; Hurst, A. W
  Geophys. Res. Lett., 30, 7, 2002, [Peer-reviewed]
  English, Scientific journal
• 2-D resistivity structure of the southern part of the Nojima fault and relationship to the activity of the faults
  Yamaguchi, S; S. Sutoh; T. Hashimoto; H. Murakami; N. Takagi
  J. Seismol. Soc. Japan, 55, 2, 143, 151, 日本地震学会, 2002, [Peer-reviewed]
  Japanese
• Measurements of zeta potential in various rock samples of Aso Volcano
  Hideaki Hase; Shin’ichi Takakura; Tsuneo Ishido; Keiko Sato; Takeshi Hashimoto; Yoshikazu Tanaka
  Annual Report - Institute for Geothermal Sciences, Graduate School of Science, Kyoto University 2001, B, 2, 3, 2002
  English
• 電磁気観測から推定される雲仙火山におけるマグマと水の相互作用
  鍵山恒臣; 橋本武志; Srigutomo, Wahyu; 神田 径; 田中良和; 宇津木 充
  月刊地球, 858, 865, 2002
  Japanese
• Electrokinetic phenomena associated with a water injection experiment at the Nojima fault on Awaji Island, Japan
  H Murakami; T Hashimoto; N Oshiman; S Yamaguchi; Y Honkura; N Sumitomo
  ISLAND ARC, 10, 3-4, 244, 251, Sep. 2001, [Peer-reviewed]
  English, Scientific journal
• Detection of crustal inhomogeneity in the Nojima Fault zone using earth current noise
  T Hashimoto
  ISLAND ARC, 10, 3-4, 306, 317, Sep. 2001, [Peer-reviewed]
  English, Scientific journal
• The 2000 activity of Miyakejima-volcano as inferred from electric and magnetic field observations
  Sasai, Y; M. Uyeshima; H. Utada; T. Kagiyama; J. Zlotnicki; T. Hashimoto; Y. Takahashi
  Journal of Geography, 110, 2, 226, 244, Tokyo Geographical Society, 2001, [Peer-reviewed]
  Japanese, Scientific journal, Electric and magnetic field observations have been extensively carried out since 1995. A precursory magnetic anomaly was detected in July 1996, which was ascribed to thermal demagnetization at a depth of several hundreds of meters beneath the southern periphery of the summit Hatcho-taira caldera. Magnetic data revealed that the large depression at the summit associated with the steam explosion on July 8, 2000 had been completed within four minutes. Since the beginning of July, anomalous magnetic changes were observed at several magnetometer sites along the central N-S line of Miyake-jima volcano, which indicated the rise of a demagnetized area from depth to the summit. On July 4, a few days before the steam explosion, an area survey of SP in the summit caldera was conducted, discovering an extremely negative zone around the forthcoming depression, which suggested the intense absorption of ground water. Tilt-step events; i.e., abrupt uplifts around the summit area, were accompanied by electric field variations, which were very similar to the velocity waveform of the ground motion, as well as magnetic variations with step-like changes. An electric field can be interpreted as being due to electric currents generated by the forced injection of steam and/or water from the pressure source (electrokinetic phenomena). Magnetic changes are attributed to the piezomagnetic effect of rocks due to increased stresses. The geomagnetic total intensity showed large variations after the July 8 eruption, the typical feature of which was positive at the east and west sides and negative along the central north-south line of the volcano. They are ascribed to 1) the loss of magnetic mass from the summit and 2) the thermal demagnetization at depth. After the August 18 eruption, which was the largest, the steep changes in total intensity became flat, which suggested that the temperature rise at depth had weakened. At the time of the August 18 eruption, a large increase in self-potential was observed around the southwestern foot of the central cone Oyama : This implies that a definite change occurred in the hydrothermal system of the volcano.
• P08 Results of Time Domain Electromagnetic (TDEM) Sounding in Eastern Part of Mount Unzen Area, Kyushu
  Srigutomo W.; Kagiyama T.; Kanda W.; Hashimoto T.; Munekane H.; Tanaka Y.; Utsugi M.; Ominato T.
  PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN, 2001, 110, 110, The Volcanological Society of Japan, 2001
  English
• Changes in the Geomagnetic Total Intensity and Self Potential Anomaly Associated with the 2000 Activity of Miyake-jima Volcano
  SASAI Yoichi; UYESHIMA Makoto; UTADA Hisashi; KAGIYAMA Tsuneomi; ZLOTNICKI Jacques
  J. Geogr., 110, 2, Plate7, Plate8, Tokyo Geographical Society, 2001
• Electromagnetic Monitoring in Usu Volcano
  Nishida Y.; Mogi T.; Sato H.; Tanimoto K.; Saba M.; Takada M.; Tanaka Y.; Hashimoto T.; Utsuki M.; Sasai Y.
  PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN, 2000, 173, 173, The Volcanological Society of Japan, 2000
  Japanese
• ASOBOI 97: Aso Seismic Observation with Broadband Instruments in 1997
  Yamamoto,M; H.Kawakatsu; S.Kaneshima; T.Iidaka; J.Oikawa; S.Watada; Y.Morita; T.Mori; T.Tsutsui; Y.Sudo; S.Yoshikawa; T.Hashimoto; M.Nakaboh
  Bull. Earthq. Res. Inst., Univ. Tokyo, 74, 267, 285, 1999
  English
• Seismic activity and ground deformation associated with 1995 phreatic eruption of Kuju Volcano, Kyushu, Japan
  Y Sudo; H Ono; AW Hurst; T Tsutsui; T Mori; M Nakaboh; Y Matsumoto; M Sako; S Yoshikawa; M Tanaka; Y Kobayashi; T Hashimoto; T Hoka; T Yamada; H Masuda; S Kikuchi
  JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH, 81, 3-4, 245, 267, May 1998, [Peer-reviewed]
  English, Scientific journal
• Tectonoelectric signal related with the occurrence of the 1995 Hyogo-ken Nanbu earthquake (M7.2) and preliminary results of electromagnetic observation around the focal area
  N Sumitomo; N Oshiman; S Sakanaka; T Goto; H Utada; Y Sasai; M Uyeshima; S Koyama; R Ishikawa; Y Honkura; H Tsunakawa; S Yamaguchi; H Inokuchi; H Murakami; Shiozaki, I; Y Tanaka; T Hashimoto; T Mogi; T Uchida; A Jomori; K Suzuki
  JOURNAL OF PHYSICS OF THE EARTH, 45, 2, 91, 104, 1997, [Peer-reviewed]
  English, Scientific journal
• Self-potential changes and subsurface hydrothermal activity accompanying the 1990-1995 eruption of Unzen Volcano
  T Hashimoto
  JOURNAL OF GEOMAGNETISM AND GEOELECTRICITY, 49, 7, 977, 993, 1997, [Peer-reviewed]
  English, Scientific journal
• 1994年地殻比抵抗研究グループ合同観測における宮崎―水俣測線のMT比抵抗モデル
  市來雅啓; 大志万直人; 住友則彦; 橋本武志; 槇野豊; 歌田久司; 鍵山恒臣; 宗包浩志; 岩切一宏
  Conductivity Anomaly研究会論文集, 1997
  Japanese, Scientific journal
• Solar and IMF effects on mid-latitude ionospheric electric fields and foF2
  T Iyemori; M Takeda; A Saito; T Araki; T Hashimoto; Y Tanaka
  JOURNAL OF GEOMAGNETISM AND GEOELECTRICITY, 48, 10, 1219, 1232, 1996, [Peer-reviewed]
  English, Scientific journal
• Co-seismic geomagnetic variations observed at the 1995 Hyogoken-Nanbu earthquake
  T Iyemori; T Kamei; Y Tanaka; M Takeda; T Hashimoto; T Araki; T Okamoto; K Watanabe; N Sumitomo; N Oshiman
  JOURNAL OF GEOMAGNETISM AND GEOELECTRICITY, 48, 8, 1059, 1070, 1996, [Peer-reviewed]
  English, Scientific journal
• A LARGE SELF-POTENTIAL ANOMALY ON UNZEN VOLCANO, SHIMABARA PENINSULA, KYUSHU-ISLAND, JAPAN
  T HASHIMOTO; Y TANAKA
  GEOPHYSICAL RESEARCH LETTERS, 22, 3, 191, 194, Feb. 1995, [Peer-reviewed]
  English, Scientific journal
• A large self‐potential anomaly on Unzen Volcano, Shimabara Peninsula, Kyushu Island, Japan
  T. Hashimoto; Y. Tanaka
  Geophysical Research Letters, 22, 3, 191, 194, 1995, [Peer-reviewed]
  English, Scientific journal
• Self-potential Measurements on Shinmoe-Dake Kirishima Volcanic Group
  Hashimoto, T; T. Kagiyama; F. Masutani
  Bull. Earthq. Res. Inst., Univ. Tokyo, 69, 257, 266, 1994, [Peer-reviewed]
  English, Research institution

• Trial application of the volcanic unrest index (VUI) to Mt Meakandake
  橋本武志; 青山裕; 田中良; 大倉敬宏; 森俊哉; 高木朗充, 日本火山学会講演予稿集, 2024, 2024
• IAVCEI（国際火山学地球内部化学協会）2023年大会参加報告（その1）：セッションとワークショップの概況
  長谷川 健; 松本 恵子; 橋本 武志; 畑 真紀; 岩橋 くるみ; 無盡 真弓; 村松 弾; 大橋 正俊; 三反畑 修; 嶋野 岳人; 田中 良; 安田 裕紀, 火山, 68, 2, 105, 113, Jun. 2023, [Peer-reviewed]
  Japanese
• Investigation of hydrothermal structure and short-term transition in Noboribetsu geothermal area based on a numerical simulation
  柘植鮎太; 田中良; 橋本武志; 青山裕, 日本地球惑星科学連合大会予稿集(Web), 2023, 2023
• An aeromagnetic survey using an unmanned aerial vehicle over Azuma Volcano
  米倉光; 米倉光; 市來雅啓; 大熊茂雄; 宮川歩夢; 田中良; 海田俊輝; 柘植鮎太; 太田豊宣; 橋本武志, 日本地球惑星科学連合大会予稿集(Web), 2023, 2023
• アトサヌプリ
  北海道大学大学院理学研究院, 令和３年度北海道受託研究「北海道における火山に関する研究」報告書, 1, 82, Mar. 2022
  Japanese

  
  Download
• 有珠山
  北海道大学大学院理学研究院, 令和２年度北海道受託研究「北海道における火山に関する研究」報告書, 1, 90, Mar. 2021
  Japanese, Others

  
  Download
• Repeated aeromagnetic surveys of Tarumae volcano using an unmanned autonomous helicopter
  渋谷桂一; 橋本武志; 早川智也; 吉川契太郎, 北海道大学地球物理学研究報告(Web), 84, 2021
• Introduction of the Special Issues on“Understanding Volcanoes by Integrating Eruptive History Research and Volcano Observations”
  奥野充; 井口正人; 三好雅也; 三浦大助; 小林淳; 橋本武志; 大場武; 佐藤鋭一; 宝田晋治, 火山, 66, 2, 2021
• 十勝岳
  北海道大学大学院理学研究院, 平成30年度北海道受託研究「北海道における火山に関する研究」報告書, 1, 96, Mar. 2020
  Japanese, Others

  
  Download
• Seismic and geodetic monitoring near the active crater at Tokachidake volcano (preliminary report)
  青山裕; 田中良; 橋本武志; 村上亮; 成田翔平, 北海道大学地球物理学研究報告(Web), 83, 2020
• Three-dimensional resistivity structure and magma plumbing system of Meakandake volcano inferred from broadband magnetotelluric survey
  井上智裕; 橋本武志; 田中良, 日本地球惑星科学連合大会予稿集(Web), 2020, 2020
• Repeated aeromagnetic survey of Noboribetsu volcano
  佐藤彰紀; 橋本武志; 早川智也; 吉川契太郎; 小山崇夫, 日本地球惑星科学連合大会予稿集(Web), 2020, 2020
• Repeated aeromagnetic survey on Kuju Volcano using drone, unmanned multicopter.
  宇津木充; 橋本武志; 佐藤彰紀; 多田訓子; 太田豊宣; 吉川慎; 井上寛之, 日本地球惑星科学連合大会予稿集(Web), 2020, 2020
• Special Techniques for Airborne Survey Technologies Using Unmanned Helicopters in Noboribetsu Volcano
  早川智也; 吉川契太郎; 橋本武志, 日本地球惑星科学連合大会予稿集(Web), 2020, 2020
• 3-D resistivity structure and magma plumbing system of Meakandake volcano inferred from broadband magnetotelluric survey
  井上智裕; 橋本武志; 田中良; 山谷祐介, 地球電磁気・地球惑星圏学会総会及び講演会(Web), 148th, 2020
• A trial application of the Volcanic Unrest Index (VUI) to Mt. Tokachidake
  橋本武志; 青山裕; 田中良; 大倉敬宏; 森俊哉, 日本火山学会講演予稿集, 2020, 2020
• Modeling of ground deformation induced by changes in permeability and hydrothermal flux within a conduit
  田中良; 橋本武志; 成田翔平, 日本火山学会講演予稿集, 2020, 2020
• The subsurface structure of Meakandake volcano inferred from three-dimensional resistivity model
  井上智裕; 橋本武志; 田中良; 山谷祐介, 日本火山学会講演予稿集, 2020, 2020
• Re-analysis of three-dimensional resistivity structure of Aso volcano
  松島喜雄; 宇津木充; 高倉伸一; 山崎雅; 畑真紀; 橋本武志; 上嶋誠, 日本火山学会講演予稿集, 2020, 2020
• 平成30年北海道胆振東部地震とその災害に関する総合調査
  高橋 浩晃; 勝俣 啓; 大園 真子; 橋本 武志; 青山 裕; 酒井 慎一; 松本 聡; 岡田 知己; 小菅 正裕; 寺川 寿子; 飯尾 能久; 中尾 茂; 上嶋 誠; 柴田 智郎; 大津 直; 高井 伸雄; 飯場 正紀; 渡部 要一; 菊地 優; 岡崎 太一郎; 白井 和貴; 西村 裕一; 石川 達也; 高瀬 裕也; 永井 宏; 宮森 保紀; 三宅 弘恵; 松島 信一; 浅野 公之; 重藤 迪子; 卜部 厚志; 前田 宜浩; 石澤 友浩; 廣瀬 亘; 小山内 信智; 山田 孝; 笠井 美青; 檜垣 大助; 風間 基樹; 千木良 雅弘; 渦岡 良介; 竹林 洋史; 木村 誇; 石丸 聡; 岡田 成幸; 内田 賢悦; 有村 幹治; 植松 武是; 多々納 裕一; 梶谷 義雄; 能島 暢呂; 田村 圭子; 中村 洋光; 戸松 誠, 自然災害科学総合シンポジウム講演論文集, 56, 56, 21, 26, 11 Sep. 2019, [Domestic magazines]
  2019年9月11日(水), 於 : キャンパスプラザ京都 第1講義室「平成30年北海道胆振東部地震」とその災害に関する総合調査を実施した。震度７を記録した揺れにより, 同時多発斜面災害と, 北海道全域同時停電(ブラックアウト)が発生し, 複合的な災害となった。震源の深さは約37kmで, 大すべり域はそれより浅い20-25km付近であった。木造家屋の倒壊が多発したむかわ町市街では, 地盤構造による地震波の増幅が見られた。同時多発斜面崩壊は, 近隣の活火山の噴火による降下火砕堆積物が素因となった。札幌市内の地盤液状化地帯では, 極めて軟弱な谷埋盛土層が確認された。地震発生が未明であったことが, 建物倒壊による直接死が出なかったことに関係している可能性がある。ブラックアウトは, 社会経済活動に大きな影響を与えた。, 京都大学防災研究所自然災害研究協議会, Japanese
• 雌阿寒岳
  北海道大学大学院理学研究院, 平成30年度北海道受託研究「北海道における火山に関する研究」報告書, 1, 77, Mar. 2019
  Japanese, Others

  
  
• 雌阿寒岳北麓における比抵抗構造探査
  井上智裕; 橋本武志, 日本火山学会講演予稿集, 2019, 2019
• 噴気連続画像の自動処理
  橋本武志, 日本火山学会講演予稿集, 2019, 2019
• 広帯域MT法データから推定される阿蘇火山のマグマ供給系と浅部熱水系
  松島喜雄; 宇津木充; 高倉伸一; 山崎雅; 畑真紀; 橋本武志; 上嶋誠, 日本地球惑星科学連合大会予稿集(Web), 2019, 2019
• 火山ガス観測における無人機の利用
  橋本武志; 寺田暁彦; 森俊哉; 田中良, 日本地球惑星科学連合大会予稿集(Web), 2019, 2019
• 十勝岳の火口近傍でとらえられた力学現象
  青山裕; 橋本武志; 田中良; 大島弘光; 齋藤公一滝; 道下剛史; 奥山哲, 日本地球惑星科学連合大会予稿集(Web), 2019, 2019
• ニセコ
  北海道大学大学院理学研究院, 平成29年度北海道受託研究「北海道における火山に関する研究」報告書, 1, 44, Mar. 2018
  Japanese, Others

  
  
• ドローンによる火山観測
  橋本武志; 寺田暁彦; 森 俊哉, 地理, 63, 29, 35, Feb. 2018
  Japanese, Introduction other
• 十勝岳火口域周辺の三次元比抵抗構造とその時間変化
  田中良; 山谷祐介; 田村慎; 橋本武志; 岡崎紀俊; 高橋良; 茂木透, 日本地球惑星科学連合大会予稿集(Web), 2018, 2018
• 無人ヘリコプターを用いた登別火山の空中調査技術の工夫点
  早川智也; 松井博幸; 押野見純司; 橋本武志, 日本地球惑星科学連合大会予稿集(Web), 2018, 2018
• 桜島・霧島・富士山・九重山での広帯域MT連続観測により推定される比抵抗構造時間変化
  相澤広記; 上嶋誠; 小山崇夫; 長谷英彰; 山谷祐介; 宇津木充; 神田径; 橋本武志; 塚本果織; 村松弾, 日本地球惑星科学連合大会予稿集(Web), 2018, ROMBUNNO.SEM16‐03 (WEB ONLY), 2018
  Japanese
• 非噴火期の地盤膨張源および消磁源の特徴について
  橋本武志; 宇津木充; 大倉敬宏; 神田径; 寺田暁彦; 三浦哲; 井口正人, 日本地球惑星科学連合大会予稿集(Web), 2018, ROMBUNNO.SVC41‐04 (WEB ONLY), 2018
  Japanese
• 有珠山における小型無人ヘリを利用した火山調査技術
  早川智也; 石田時代; 橋本武志; 吉本充宏, 建設機械, 53, 6, 1, 8, Jun. 2017
  日本工業出版, Japanese, Introduction commerce magazine
• 樽前山
  北海道大学大学院理学研究院, 平成28年度北海道受託研究「北海道における火山に関する研究」報告書, 1, 51, Mar. 2017
  Japanese, Others

  
  
• 電磁気探査（MT/AMT法探査）：火山体内部構造・熱水流動系のモデル化と火山活動度評価手法の高度化（十勝岳）
  田村 慎; 橋本武志; 茂木 透; 山谷祐介; 奥田真央, 北海道地質研究所調査研究報告, 44, 69, 103, Mar. 2017
  Japanese, Report research institution
• 全磁力観測：火山体内部構造・熱水流動系のモデル化と火山活動度評価手法の高度化（十勝岳）
  橋本武志; 青山 裕; 田中 良, 北海道地質研究所調査研究報告, 44, 105, 111, Mar. 2017
  Japanese, Report research institution
• Three-dimensional resistivity structure beneath Aso caldera using broadband MT data
  MATSUSHIMA Nobuo; TAKAKURA Shinichi; HATA Maki; UTSUGI Mitsuru; HASHIMOTO Takeshi; UYESHIMA Makoto, PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN, 2017, 46, 46, 2017
  The Volcanological Society of Japan, Japanese
• ドローンを用いた空中磁気観測システムの開発
  宇津木充; 橋本武志; 城森敦善, 日本地球惑星科学連合大会予稿集(Web), 2017, 2017
• 焼岳での電磁気観測-広帯域MT観測および磁気探査-
  吉村令慧; 橋本武志; 宮崎真大; 中川潤; 加茂正人; 菅野倖大朗; 高田将仁; 三浦勉; 中本幹大; 荒上夏奈; 山崎健一; 大見士朗; 井口正人, 日本地球惑星科学連合大会予稿集(Web), 2017, 2017
• 非噴火時における火山浅部熱水系の時間発展と地上観測への応答
  田中良; 橋本武志; 松島喜雄; 石戸経士, 日本地球惑星科学連合大会予稿集(Web), 2017, 2017
• Report of the IAVCEI 2017 Scientific Assembly
  HASHIMOTO Takeshi; TANAKA Ryo; UESAWA Shimpei; YAMADA Taishi; HASEGAWA Takeshi; KOZONO Tomofumi; MANNEN Kazutaka; NAKAMICHI Haruhisa; SUMITA Mari; SUZUKI Yuki; TAJIMA Yasuhisa; TAKAGI Akimichi, BULLETIN OF THE VOLCANOLOGICAL SOCIETY OF JAPAN, 62, 4, 189, 196, 2017, [Peer-reviewed]
  The Volcanological Society of Japan, Japanese, Introduction scientific journal
• Magma pathway beneath Aso caldera inferred from 3-D electrical resistivity structure
  HATA Maki; TAKAKURA Shinichi; MATSUSHIMA Nobuo; HASHIMOTO Takeshi; UTSUGI Mitsuru, PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN, 2016, 96, 96, 2016
  The Volcanological Society of Japan, Japanese
• 熱水流動を考慮した熱水系卓越火山における地磁気全磁力変化・地盤変動モデル(その1)-十勝岳2008-2009年の変化を例として-
  田中良; 橋本武志; 石戸経士; 松島喜雄, 日本地球惑星科学連合大会予稿集(Web), 2016, 2016
• 十勝岳における簡易型マルチガス観測(続報)
  岡本理沙; 橋本武志, 日本地球惑星科学連合大会予稿集(Web), 2016, 2016
• 2016年熊本‐九州中部地震活動領域の電気比抵抗構造
  相澤広記; 麻植久史; 小池克明; 高倉伸一; 松島喜雄; 畑真紀; 吉永徹; 橋本武志; 宇津木充; 井上寛之; 塩谷太郎; 上嶋誠; 小山崇夫; 神田径; 内田和也; 塚島祐子; 志藤あずさ; 藤田詩織; 若林翌馬; 塚本果織; 松島健; 吉村令慧; 山崎健一; 小松信太郎; 田村慎, 日本地球惑星科学連合大会予稿集(Web), 2016, ROMBUNNO.MIS34‐P26 (WEB ONLY), 2016
  Japanese
• UAVを用いた御嶽山の噴煙観測
  森俊哉; 橋本武志; 寺田暁彦; 篠原宏志; 風早竜之介; 吉本充宏; 田中良, 日本地球惑星科学連合大会予稿集(Web), 2015, 2015
• 北海道東部地域における地磁気三成分永年変化
  三嶋渉; 橋本武志; 茂木透, 日本地球惑星科学連合大会予稿集(Web), 2015, 2015
• バーチャルMulti-GAS法による十勝岳と樽前山の火山ガス観測
  岡本理沙; 橋本武志; 田中良, 日本地球惑星科学連合大会予稿集(Web), 2015, 2015
• P88 Geomagnetic Variations during Inter-eruptive Periods at Volcanoes with an Epithermal System
  HASHIMOTO Takeshi; KANDA Wataru; UTSUGI Mitsuru; ICHIKI Masahiro; KOYAMA Takao, PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN, 2015, 0, 186, 186, 2015
  The Volcanological Society of Japan, Japanese
• B1-01 Re-examination of the geomagnetic changes in the early stage of the Usu 2000 eruption
  Hashimoto Takeshi; Mishima Wataru, Programme and abstracts the Volcanological Society of Japan, 2014, 55, 55, 02 Nov. 2014
  Volcanological Society of Japan, Japanese
• B1-02 AMT resistivity survey in the crater area of Tokachi-dake Volcano
  Yamaya Yusuke; Takahashi Ryo; Okazaki Noritoshi; Tamura Makoto; Oka Daisuke; Akita Fujio; Mogi Toru; Hashimoto Takeshi; Michishita Takeshi; Tanaka Ryo; Sugano Kotaro; Okuda Mao, Programme and abstracts the Volcanological Society of Japan, 2014, 56, 56, 02 Nov. 2014
  Volcanological Society of Japan, Japanese
• P1-07 Evaluation of thermal activity at Tokachi-dake 1-Estimation of gas heat fluxes by Plume rise method
  Tanaka Ryo; Hashimoto Takeshi; Terada Akihiko, Programme and abstracts the Volcanological Society of Japan, 2014, 125, 125, 02 Nov. 2014
  Volcanological Society of Japan, Japanese
• 有珠山2000年新山ボーリングコアの岩石磁気学的検討
  MISHIMA WATARU; HASHIMOTO TAKESHI; MIKI DAISUKE; OSHIMA HIROMITSU, 日本火山学会講演予稿集, 2014, 148, 148, 2014
  The Volcanological Society of Japan, Japanese
• 樽前山の群発地震活動と石狩地方南部の地震(M_JMA5.6)
  AOYAMA HIROSHI; MORI HITOSHI; HASHIMOTO TAKESHI; OSHIMA HIROMITSU; MURAKAMI MAKOTO, 日本火山学会講演予稿集, 2014, 52, 52, 2014
  The Volcanological Society of Japan, Japanese
• 樽前山の2013年群発地震活動
  AOYAMA HIROSHI; HASHIMOTO TAKESHI; MORI HITOSHI; OSHIMA HIROMITSU; MURAKAMI MAKOTO; USUI YUJI; MIYAMOTO MASASHI, 日本火山学会講演予稿集, 2013, 33, 33, 2013
  The Volcanological Society of Japan, Japanese
• 2011年霧島火山(新燃岳)噴火に関する総合調査(2)
  中田節也; 森田裕一; 清水洋; 宮町宏樹; 中道治久; 大久保修平; 石原和弘; 中尾茂; 大倉敬宏; 植木貞人; 大島弘光; 上嶋誠; 橋本武志; 野上健治; 森俊哉; 小林哲夫; 宮縁育夫; 下川悦郎; 地頭薗隆; 清水収, 自然災害科学総合シンポジウム要旨集, 49th, 1, 6, 11 Sep. 2012
  Japanese
• アトサヌプリ
  北海道大学大学院理学研究院, 平成23年度北海道受託研究「北海道における火山に関する研究」報告書, 1, 147, Mar. 2012
  Japanese, Others

  
  
• カルデラ直下・地殻中深部の低比抵抗異常-支笏カルデラ・屈斜路カルデラの例-
  山谷祐介; 本多亮; 茂木透; 長谷英彰; 市原寛; 橋本武志; 上嶋誠, 日本火山学会講演予稿集, 2012, 2012
• 広帯域MT探査による霧島火山群の3次元比抵抗構造と異常位相のモデリング
  相澤広記; 小山崇夫; 上嶋誠; 長谷英彰; 山谷祐介; 橋本武志; 神田径; 小川康雄; 宇津木充; 吉村令慧; 山崎健一, 地球電磁気・地球惑星圏学会総会及び講演会予稿集(CD-ROM), 132nd, ROMBUNNO.A003-10, 2012
  Japanese
• B1-12 3D resistivity structure of Kirishima volcano inferred from broad-band magnetotelluric data
  Aizawa Koki; Yoshimura Ryokei; Yamazaki Ken'ichi; Koyama Takao; Uyeshima Makoto; Hase Hideaki; Yamaya Yusuke; Hashimoto Takeshi; Kanda Wataru; Ogawa Yasuo; Utsugi Mitsuru, PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN, 2012, 0, 2012
  The Volcanological Society of Japan, Japanese
• P84 Shallow 3-D resistivity structure of Sakurajima volcano
  Kanda W; Utsugi M; Ogawa Y; Takakura S; Koyama T; Hashimoto T; Komori S; Sonoda T; Sato I; Inoue N, PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN, 2012, 0, 2012
  The Volcanological Society of Japan, Japanese
• P85 Repeated aeromagnetic survey on Sakurajima volcano (2007 - 2010)
  Utsugi M; Kanda W; Hashimoto T; Inoue N; Komori S; Inoue H; Iguchi M, PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN, 2012, 0, 2012
  The Volcanological Society of Japan, Japanese
• 観測紹介(霧島山広帯域MT観測)
  相澤広記; 小山崇夫; 長谷英彰; 上嶋誠; 橋本武志; 神田径; 小川康雄; 宇津木充; 吉村令慧, 物理探査ニュース, 12, 1, 2, Oct. 2011
  Japanese
• MT survey in Akanko Hot Springs
  MOGI Toru; YAMAYA Yusuke; HASHIMOTO Takeshi; AKITA Fujio; SHIBATA Tomoo; TAKAHASHI Tetsuya; TAMURA Shin, 物理探査学会学術講演会講演論文集 = Proceeding of the SEGJ Conference, 125, 147, 150, 13 Sep. 2011
  Japanese
• 2011年霧島火山(新燃岳)噴火に関する総合調査―噴火準備過程,噴火現象,噴火に伴う土砂災害―
  中田節也; 森田裕一; 清水洋; 宮町宏樹; 中道治久; 大久保修平; 石原和弘; 中尾茂; 大倉敬宏; 植木貞人; 大島弘光; 上嶋誠; 橋本武志; 鍵山恒臣; 神田径; 野上健治; 森俊哉; 小林哲夫; 宮縁育夫; 下川悦郎; 地頭薗隆; 清水収, 自然災害科学総合シンポジウム要旨集, 48th, 1, 6, 13 Sep. 2011
  Japanese
• Geotechnical estimation of long tunnel site by time-domain helicopter-borne electromagnetic method
  OKAZAKI Kenji; MOGI Toru; UTSUGI Mitsuru; YAMAZAKI Takashi; ITO Yoshihiko; HASHIMOTO Takeshi; YAMAYA Yusuke; ITO Hisatoshi; KAIEDA Hideshi; TSUKUDA Kazuhiro; YUKI Yoichi; JOMORI Akira; KUNISHIMA Hideki; TAKAHASHI Yukitsugu, 物理探査学会学術講演会講演論文集 = Proceeding of the SEGJ Conference, 124, 306, 309, 10 May 2011
  Japanese
• 樽前山
  北海道大学大学院理学研究院, 平成22年度北海道受託研究「北海道における火山に関する研究」報告書, 1, 35, Mar. 2011
  Japanese, Others

  
  
• 民生デジタルカメラを利用した簡易SO₂カメラの製作
  橋本武志; 八神樹; 寺田暁彦; 江尻省; 中村卓司; 阿保真; 吉川慎, 日本火山学会講演予稿集, 2011, 2011
• A2-01 Temporal changes in electrical resistivity of Kirishima volcano from continuous magnetotelluric observations
  Aizawa Koki; Koyama Takao; Hase Hideaki; Uyeshima Makoto; Hashimoto Takeshi; Utsugi Mitsuru; Yoshimura Ryokei; Kanda Wataru; Ogawa Yasuo, PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN, 2011, 0, 23, 23, 2011
  The Volcanological Society of Japan, Japanese
• B2-12 Cooling processes following eruptions at Usu Volcano, as inferred from aeromagnetic repeat surveys
  Hashimoto T; Nakatsuka T; Okuma S; Utsugi M; Koyama T; Kanda W, PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN, 2011, 0, 89, 89, 2011
  The Volcanological Society of Japan, Japanese
• P09 Broad-band MT survey around Shinmoe-dake, Kirishima volcanos
  Koyama Takao; Hashimoto Takeshi; Yagami Itsuki; Kanda Wataru; Ogawa Yasuo; Kagiyama Tsuneomi; Utsugi Mitsuru; Yoshimura Ryokei; Yamazaki Ken'ichi; Komatsu Shintaro; Uyeshima Makoto; Hase Hideaki; Aizawa Koki; Yamaya Yusuke; Sugano Takayuki; Watanabe Atsushi; Miyakawa Koji; Maehara Yuki, PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN, 2011, 0, 121, 121, 2011
  The Volcanological Society of Japan, Japanese
• P37 Remote sensing of the water amount of volcanic fumarole gas using lidar technique
  Ejiri Mitsumu K; Nakamura Takuji; Suzuki Hidehiko; Abo Makoto; Hashimoto Takeshi; Terada Akihiko, PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN, 2011, 0, 2011
  The Volcanological Society of Japan, Japanese
• P38 A Portable Lidar for Temperature Measurement of Volcanic Fumarole Gas
  Ikeba K; Abo M; Hashimoto T; Terada A; Ejiri M; Nakamura T, PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN, 2011, 0, 2011
  The Volcanological Society of Japan, Japanese
• Magnetic changes on Usu Volcano detected by repeat airborne surveys
  Hashimoto, T; M. Utsugi; T. Nakatsuka; S. Okuma; T. Koyama; W. Kanda; A. Suzuki, Conductivity Anomaly Research, 29, 36, 2011
  Japanese
• Absolute magnetic measurements in the eastern Hokkaido (2)
  Hashimoto, T; T. Mogi; J. Shimizu; T. I, Conductivity Anomaly Research, 21, 28, 2011
  CA研究グループ, Japanese
• Repeat Surveys of Self-potential in Tokachidake Volcano
  Miyamura, J; N. Okazaki; Y. Fushiya; N. Shigeno; T. Hashimoto, Geophysical Bulletin of Hokkaido University, 74, 74, 1, 19, 2011
  We have performed repeat surveys of self-potential (SP) in Tokachidake Volcano since1995, in which some elevated volcanic activity followed the appearance of fumaroles at 62-0Crater. Since thermal anomalies had always preceded to the eruptions at Tokachidake in the last100 years, we expected some temporal and spatial variations of SP anomalies accompanying thethermal activity beneath active craters.Topography-related SP distribution was seen on the northwestern flank in the surveys of1995, 2008 and 2010. This characteristic feature with a gradient of -0.3 mV/m was independentof the survey year and thus thought to be generated from stable flow of ground water. Weassumed that the gradient is uniform over the survey area and corrected the topographic effectprior to the following analyzes in order to emphasize the SP of volcanic origins.We found positive SP anomalies on 62-Craters and Taisho Crater where thermal anomalieshave been seen throughout our SP surveys. These SP anomalies are probably related to thehydrothermal activity beneath the craters but the corresponding electrokinetic current sources shouldnot be very deep since spatial size of these SP anomalies are smaller than a few hundred meters.We also detected temporal variations of SP anomalies corresponding to the thermal activity at62-Craters. The positive SP anomaly on 62-Craters gradually developed toward 1998 up to +100mV, being accompanied by an increase of thermal activity. The anomaly showed a subsequentattenuation down to -50 mV by 2001 in accordance with a decrease of thermal activity. Inaddition, another large positive SP anomaly with an amplitude of approximately +200mV appearednear the active fumaroles on Taisho Crater where fuming was enhanced in 2010. The result ofour SP surveys implies that main thermal activity in the near future may develop at Taisho Craterrather than at 62-Craters. We point that attention should be paid not only to 62-Craters but alsoto Taisho Crater in monitoring the volcanic activity until the next eruption at Tokachidake., 北海道大学大学院理学研究院自然史科学部門（地球物理学）, Japanese
• 1-A05 有珠山周辺における高校での火山観測実習(火山教育とジオパーク1,口頭発表)
  一岡 祐生; 梅原 宏之; 大島 弘光; 橋本 武志; 青山 裕, 日本火山学会講演予稿集, 2010, 09 Oct. 2010
  特定非営利活動法人日本火山学会, Japanese
• Laser remote sensing of volcanic fumarole gas temperature
  阿保 真; 橋本 武志; 中村 卓司, センシングフォ-ラム資料, 27, 348, 351, 27 Sep. 2010
  〔計測自動制御学会〕, Japanese
• 十勝岳における自然電位繰り返し測定
  宮村淳一; 岡崎紀俊; 伏谷祐二; 重野伸昭; 橋本武志, 日本火山学会講演予稿集, 2010, 2010
• 有珠山頂域の全磁力変化
  橋本武志; 鈴木敦生; 松本征海, 日本火山学会講演予稿集, 2010, 2010
• P51 Magnetotelluric surveys in and around the Aira caldera (2)
  Kanda W; Tank S. B; Kaya T; Ogawa Y; Kasaya T; Yakiwara H; Ichihara H; Hashimoto T; Koyama T; Utsugi M; Inoue H; Sonoda T, PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN, 2010, 0, 2010
  The Volcanological Society of Japan, Japanese
• Absolute magnetic measurements in the eastern Hokkaido
  Hashimoto, T; T. Mogi; M. Nishimura; S. Arita, Conductivity Anomaly Research, 56, 63, 2010
  CA研究グループ, Japanese
• Three-dimensional resistivity structure around the 62-II crater at Tokachidake volcano
  Yamaya, Y; T. Hashimoto; T. Mogi; M. Murakami; N. Okazaki; M. Yoshimoto; Y. Fushiya; M. Hashimoto; T. Yamamoto; M. Nishimura; S. Arita; A. Matoba; R. Tsuchiya, Geophysical Bulletin of Hokkaido University, 73, 73, 281, 294, 2010
  Tokachidake Volcano is an active volcano, situated at the SW end of the Daisetsu-Tokachi volcanic chain in the central Hokkaido, Japan. We performed the AMT resistivity survey around the 62 -II crater at the volcano in order to realize the hydrothermal zone, focusing on the recent activity of the crustal inflation and demagnetization beneath the crater. The measured AMT data suggested the three-dimensional structure beneath the study area. Prior to the resistivity modeling, we estimated an effect due to a steep topography in the study area. This estimation clearly showed a strong effect to the apparent resistivity, impedance phase and induction vector. Therefore, the simplified topography was included to the three-dimensional model. The resistivity model supposed by a forward modeling was characterized by a conductor （0.5Ωm） beneath the 62-II crater. We investigated a physical condition which could bring the resistivity of 0.5Ωm, and then estimated that high porosity （0.3）rocks were saturated with hot（～200℃）pore water including dissolved components. Although the origin of hydrothermal water has been unresolved, this result suggests that a hydrothermal zone is developed beneath the 62-II crater., 北海道大学大学院理学研究院自然史科学部門（地球物理学）, Japanese
• Heat accumulation beneath Tokachidake volcano as inferred from magnetic changes
  Hashimoto, T; M. Nishimura; S. Arita; T. Yamamoto; M. Ogiso; N. Shigeno; N. Okazaki; T. Mogi, Geophysical Bulletin of Hokkaido University, 73, 73, 269, 280, 2010
  We report the recent results of geomagnetic repeat surveys aiming for the detection of subsurface thermal changes at Tokachidake volcano, central Hokkaido, northern Japan. We conducted the first survey in October, 2008. The same pegs and marks were reoccupied in July and September, 2009. During this period a clear dipolar pattern of magnetic changes was detected around the 62-II crater, the present main vent of Tokachidake. This change is quite consistent with the pattern due to a demagnetized sphere placed at a depth of 150 m（1,600 m a.s.l.）beneath the 62-II crater. The change of magnetic moment amounts to 1 - 2×106 Am2. The maximum magnetic change is about 35 nT, overwhelming the errors due to extra-terrestrial changes, secular changes, or seasonal variations. The most likely explanation of this demagnetization is the thermomagnetic effect due to heating beneath the crater. Considering the moderate fumarolic temperature in the 62-II crater, the thermal demagnetization is not caused directly by magma intrusion. We here propose a model that water vapor supplied from depths is releasing latent heat through condensation at the source depth. The heating rate corresponding to the observed magnetic changes is an order of 10 MW. A more speculative suggestion is that water vapor of 107～108 kg/yr is required to realize this heating rate. Considering the fact that fumarolic activity of 62-II crater has somewhat declined since 2006, the ongoing demagnetization may be attributed to the decrease of heat discharge rate from the crater. If this is the case, elevation of heat supply from depths is not necessarily required., 北海道大学大学院理学研究院自然史科学部門（地球物理学）, Japanese
• P03 Relocation of volcanic earthquakes in Mt. Tarumae, Hokkaido
  Tsuchiya Ryohei; Aoyama Hiroshi; Hashimoto Takeshi; Mori Hitoshi; Oshima Hiromitsu; Suzuki Atsuo; Matoba Atsushi; Ozaki Takeshi, Programme and abstracts the Volcanological Society of Japan, 2009, 10 Oct. 2009
  特定非営利活動法人日本火山学会, Japanese
• 十勝岳の全磁力変化と蓄熱過程(2008-2009)
  橋本武志; 西村三治; 山本輝明; 有田真; 重野伸昭; 小木曽仁; 岡崎紀俊; 茂木透, 日本火山学会講演予稿集, 2009, 2009
• 噴気温度計測用可搬型ライダーの開発
  阿保真; 橋本武志; 中村卓司; 江尻省; 寺田暁彦, リモートセンシングシンポジウム講演論文集, 35th, 2009
• 小型ラマンライダーによる火山噴気中の水蒸気分布のフィールド観測
  中村卓司; 太田修史; 橋本武志; 寺田暁彦; 阿保真; 江尻省, リモートセンシングシンポジウム講演論文集, 35th, 2009
• ラマンライダーによる火山噴気中の水蒸気分布の観測
  太田修史; 中村卓司; 寺田暁彦; 橋本武志; 阿保真, 大気圏シンポジウム・講演集(Web), 23rd, 2009
• 広帯域MT観測から推定される阿蘇カルデラの比抵抗構造
  宇津木充; 鍵山恒臣; 小森省吾; 井上寛之; 橋本武志; 小山崇夫; 小川康雄; 神田径; 山崎友也; 長町信吾; 石田 憲久, 第4回阿蘇火山の集中総合観測報告書, 2009, [Peer-reviewed]
  Japanese
• Aeromagnetic anomaly change associated with volcanic activity: an application of the generalized mis-tie control method to Asama data
  Nakatsuka, T; M. Utsugi; S. Okuma; Y. Tanaka; T. Hashimoto, Conductivity Anomaly Research, 108, 114, 2009
  CA研究グループ, Japanese
• Resistivity Structure around the Ishikari-teich-toen fault zone, Hokkaido, Japan
  Yamaya, Y; T. Mogi; H. Hase; H. Yamashita; A. Suzuki; T. Hashimoto, Conductivity Anomaly Research, 23, 30, 2009
  CA研究グループ, Japanese
• Inner structure of Komezuka scoria cone
  Hashimoto, T; M. Utsugi; S. Komori, Aso volcano, in Report of Joint research program for Aso volcano, 43, 55, 2009
  Japanese
• Magnetotelluric investigations along the eastern foot of Usu volcano
  Takakura, S; T. Hashimoto; Y. Ogawa; H. Inoue; Y. Yamaya; H. Ichihara; T. Mogi; M. Utsugi; N. Matsushima; H. Satoh, Geophysical Bulletin of Hokkaido University, 72, 72, 117, 124, 2009
  We conducted magnetotelluric surveys on the eastern flank of Usu Volcano. Analyses of the induction vector and 2-D resistivity inversion along the NNE-SSW direction have been performed. The overall structure of this area is characterized by horizontally stratified resistivity of H-L-H-L from surface to depths. A distinct low-resistivity body lies beneath the Showa-Shinzan lava dome at 2-3 km deep, below which an isolated high-resistivity body has been estimated., 北海道大学大学院理学研究院自然史科学部門（地球物理学） = Department of Natural History Sciences (Geophysics), Graduate School of Science, Hokkaido University, Japanese
• Magnetic survey at the 2000 eruption area of Usu volcano
  Koike, T; H. Hasegawa; I. Fujii; T. Hashimoto, Geophysical Bulletin of Hokkaido University, 70, 72, 107, 115, 2009
  We conducted a total field magnetic survey in the 2000 eruption area of Mt Usu. A distinct negative magnetic anomaly was found in the geothermal field in the NW part of the survey area. Meanwhile, no clear magnetic anomaly was found around N-B crater, where active fumaroles were seen. Regarding the negative anomaly in the geothermal field, we performed a 3-D inversion of demagnetized prism model. As a result it has been suggested that the magnetic anomaly is due to the demagnetization at a small depth less than 70 m from the ground surface., 北海道大学大学院理学研究院自然史科学部門（地球物理学） = Department of Natural History Sciences (Geophysics), Graduate School of Science, Hokkaido University, Japanese
• Resistivity structure beneath the doming zone of the Usu 2000 eruption
  Hashimoto, T; Y. Ogawa; S. Takakura; Y. Yamaya; H. Ichihara; M. Utsugi; H. Inoue; T. Koike; H. Hasegawa; T. Mogi, Geophysical Bulletin of Hokkaido University, 72, 72, 79, 105, 2009
  In the 2000 eruption of Usu volcano, it is widely believed that magmatic intrusion has reached the shallow subsurface to produce significant ground deformation. We performed a magnetotelluric survey over this area aiming for prospecting the intruded magma. The resistivity section exhibits a High-Low-High three-layered structure. The surface layer with a resistivity around 100 Ωm is likely to correspond with the lower Pleistocene andesite. The second layer is very conductive (0.1 to 1 Ωm), thinning and shallowing in the middle. It is difficult to explain such a low resistivity by anything but the Neogene units containing conductive clay minerals with high salinity ground water. Below it the resistivity gradually increases. The top middle part of the third layer shows the resistivities around 10 Ωm. It looks that this part is pushing the second layer upwards. We investigated whether this block is explainable by intruded magma or not from a viewpoint of the resistivity values. We at first calculated the resistivities of rhyolitic melt by using Gaillard (2004) 's model. The melt resistivities are in a range from 1 to 10 Ωm for 800 to 600 ℃. Secondly, we examined the partial melt by using the MBL model of Schilling et al. (1997). Given that the resistivities of melt and solid are 1 and 10,000 Ωm, respectively, the melt fraction corresponding to the bulk resistivity of 10 Ωm should be 15 vol%. Higher melt resistivity requires a larger melt fraction. The discussion above predicts that the bulk resistivity of the intruded magma will increase by some orders of magnitude in the course of cooling and solidification and that this process can be monitored by MT repeat measurements., 北海道大学大学院理学研究院自然史科学部門（地球物理学） = Department of Natural History Sciences (Geophysics), Graduate School of Science, Hokkaido University, Japanese
• A38 Numerical study of crater lake at Aso volcano, Japan : Variations of water temperature and concentration of dissolved ionized solid in the water
  Terada Akihiko; Yoshikawa Shin; Hashimoto Takeshi; Kagiyama Tsuneomi; Sasaki Hisashi, Programme and abstracts the Volcanological Society of Japan, 2008, 10 Oct. 2008
  Volcanological Society of Japan, Japanese
• 樽前山
  北海道大学大学院理学研究院, 平成19年度北海道受託研究「北海道における火山に関する研究」報告書, 1, 56, Mar. 2008
  Japanese, Others

  
  
• Active Source Seismic Experiment in Asama Volcano, Japan: The Outline of the Experiment and First Arrival Times
  青木陽介; 武尾実; 辻浩; 小山悦郎; 青山裕; 藤松淳; 松本聡; 宮町宏樹; 中道治久; 大倉敬宏; 大湊隆雄; 及川純; 棚田理絵; 筒井智樹; 山本圭吾; 山本希; 山里平; 山脇輝夫; 市原美恵; 井本良子; 風間卓仁; 小山崇夫; 前田裕太; 前野深; 森田裕一; 中田節也; 中村祥; 長田昇; 渡辺秀文; ALANIS P.K.B.; ANGGONO T.; 藤原善明; 福山由朗; 萩原慎太郎; 橋本武志; 平野舟一郎; 堀口桂香; 飯島聖; 石原吉明; 石川渓太, 東京大学地震研究所彙報, 83, 1, 2008
• 有珠山西山火口周辺での地温・電磁気・水質調査
  田村慎; 高橋徹哉; 秋田藤夫; 岡崎紀俊; 柴田智郎; 鈴木隆広; 荻野激; 橋本武志; 茂木透, 日本火山学会講演予稿集, 2008, 2008
• 第10回 桜島火山の集中総合観測 桜島火山におけるAMT法比抵抗構造調査
  神田径; 山崎友也; 橋本武志; 坂中伸也; 山田健太; 小川康雄; 相澤広記; 高倉伸二; 小山崇夫; 小林宰; 小森省吾, 第10回桜島火山の集中総合観測 平成19年6月-平成20年3月, 89, 104, 2008
  Japanese
• Joint Observation Campaign of Sakurajima Volcano in 2007 – A preliminary report of EM field experiments-
  Kanda, W; T. Hashimoto; T. Hurst; S. Sakanaka; K. Yamada; Y. Ogawa; K. Aizawa; S. Takakura; A. Okubo; T. Koyama; T. Kobayashi; Y. Tanaka; M. Utsugi; H. Inoue; S. Komori; K. Ishihara; Y. Yamazaki; T. Takayama; T. Tameguri, Conductivity Anomaly Research, 131, 134, 2008
  CA研究グループ, Japanese
• The reason why hot crater lake of Aso volcano is maintained for 1,500 years
  Terada, A; T. Hashimoto, Chikyu Monthly, S60, 60, 121, 132, 2008
  海洋出版, Japanese
• Resistivity Structure of Three Volcanoes in Southern Hokkaido
  YAMAYA Yusuke; HASHIMOTO Takeshi; MOGI Toru, 物理探査学会学術講演会講演論文集 = Proceeding of the SEGJ Conference, 117, 243, 245, 01 Oct. 2007
  Japanese
• Self-potential survey on usu volcano, 2006 campaign
  Hideaki Hase; Takeshi Hashimoto; Yasunori Nishida; Mitsuru Utsugi; Hiroyuki Inoue; Mizue Saba, Journal of the Hokkaido University, Faculty of Science, Series VII: Geophysics, 70, 43, 52, 2007
  Japanese, Book review
• 小型ラマンライダーによる火山噴気中の水蒸気観測
  中村卓司; 橋本武志; 寺田暁彦; 勝部祐一; 佐藤陽介; 津田敏隆; 阿保真, 日本気象学会大会講演予稿集, 92, 2007
• 可搬型水蒸気ラマンライダーの小型化に関する研究
  勝部祐一; 中村卓司; 津田敏隆; 橋本武志; 寺田暁彦, 大気圏シンポジウム, 21st, 2007
• 可搬型ラマンライダーによるフィールド観測-火山噴気の水蒸気測定-
  中村卓司; 橋本武志; 寺田暁彦; 杉本尚悠; 勝部祐一; 佐藤陽介; 津田敏隆; 阿保真, 地球電磁気・地球惑星圏学会総会及び講演会予稿集(CD-ROM), 122nd, 2007
• Aeromagnetic anomaly change detected from the Asama Volcano 2005 and 1992 data
  Nakatsuka, T; M. Utsugi; S. Okuma; Y. Tanaka; Joint; group; for; Asama volcano EM experiment; T. Hashimoto, Conductivity Anomaly Research, 120, 125, 2007
  Japanese
• Total magnetic field survey in the Nishiyama crater area of Usu volcano
  Koike, T; H. Hasegawa; I. Fujii; T. Ohwada; T. Tokumoto; T. Ohkawa; T. Hashimoto, Conductivity Anomaly Research, 130, 135, 2007
  Japanese
• Micro-earthquake activity at Usu volcano revealed by temporary dense observation
  Aoyama, H; S. Onizawa; T. Tameguri; A. Suzuki; T. Maekawa; H. Oshima; H. Mori; T. Hashimoto; T. Shiga; H. Koyama; M. Nakahashi; A. Yoshikawa; Y. Fukuyama, Geophysical Bulletin of Hokkaido Universit, 70, 70, 107, 121, 2007
  We performed temporary dense observation at Usu volcano in summer 2006, aiming toreveal micro-earthquake activity under the summit crater during dormant period of thevolcanic activity. During about 80 days of temporary observation, more than 330 volcanicearthquakes were observed. Of these earthquakes, well-recorded 142 events are selected forrelocation analysis assuming the 3D-velocity structure model which is a result of theexplosion seismic experiment at Usu volcano in 2001. Following the result of relocation, weestimated focal mechanism of 7 earthquakes whose magnitudes are more than 1.0. Thetemporal observation and analyses gave us three new insights about seismic activity; 1)Continuous activity of volcanic earthquake is seen at the shallow part under the southerncrater floor, 2) Hypocentral regions are distributed along the SW end of the U-shaped faultwhich was built in the 1977-1982 eruption associated with the uplift of Usu-Shinzan cryptdome, 3) Strike direction of the 7 major earthquakes are almost parallel to the U-shaped fault,and dominant mechanism is dip-slip type which suggests subsidence of summit domesrelative to the southern crater floor., 北海道大学大学院理学研究院自然史科学部門（地球物理学）, Japanese
• Self-potential Survey on Usu Volcano, 2006 Campaign
  Hase, H; T. Hashimoto; Y. Nishida; M. Utsugi; H. Inoue; M. Saba, Geophysical Bulletin of Hokkaido University, 70, 70, 43, 52, 2007
  We conducted self-potential (SP) surveys on Usu volcano since July to December 2006.The compiled SP map reveals positive anomalies around Ko-Usu lava dome and at the foot ofthe volcano, and a negative anomaly on the top of O-Usu lava dome. The SP profile on thesummit caldera shows the same pattern of 1985's. However, the peak-to-peak variation ofthe SP value is different: the 1985's of that shows 1000 mV while the 2006's shows 1400 mV.Topographic effect is clearly shown along the southwestern foot of the volcano, in whichcoefficient is about -2.5 mV/m. The SP profile corrected of the topographic effect reveals alarge and extensive positive anomaly over +600mV and several local positive anomalies over+1000 mV on the summit caldera. The corrected SP also reveals that a positive anomaly atthe south part of Ko-Usu lava dome and a negative anomaly at the O-Usu lava dome do notexist. The revealed positive SP anomalies are likely to be affected by an extensive alteredlayer, located beneath the summit caldera. The largest positive anomaly is shown on theridge of Usu-Shinzan cryptodome after topographic correction. This anomaly is notregarded to be formed by hydrothermal upwelling, because any indications of fumarolic andgeothermal activities have not been observed on the ridge of the volcano. The SP anomalymay be affected by intruded material into the volcano. The SP amplitude in the northwestern part of Nishiyama is very small in spite of rugged topography. An extensive lowresistivity layer (< 10 ohm-m) located in the shallow part in the northwestern of Nishiyamaprobably shields the SP variation., 北海道大学大学院理学研究院自然史科学部門（地球物理学）, Japanese
• Geothermal structure of the crust and the upper mantle in Hokkaido, Japan: A review
  Nishida, Y; T. Hashimoto, Geophysical Bulletin of Hokkaido University, 70, 70, 1, 12, 2007
  Many researchers have studied the thermal state of the crust and the upper mantle andits tectonic implications in Hokkaido, Japan. Terrestrial heat flow data have revealed thefollowing characteristic features: (1) High heat flow (84〜125 mW/m2) is observed in thebackarc side of the volcanic front, while low heat flow (< 42 mW/m2) is observed in the forearcside, showing the typical thermal aspects of the island arc. (2) The central axis zone ofHokkaido (the Kamuikotan and Hidaka metamorphic belts) shows relatively low heat flow(42〜80 mW/m2). The low heat flow zone extends for Sakhalin. (3) Extremely low (25〜34mW/m2) and high (125 〜210 mW/m2) heat flow is distributed locally on theIshikari-Tomakomai low land and its neighbor on the west, respectively.Based on the heat flow data and other geophysical data, such as the seismic velocitystructure, aeromagnetic data, and so on, the Curie point depth, the solidus temperaturedepth, temperature at the Moho, and the mantle heat flow have been estimated. Theestimated thermal structure implies the temperature of the lower crust comes to the solidustemperature beneath the backarc side of Hokkaido. The result is well supported by theelectrical resistivity soundings: the low resistive layer (10~40 ohm-m) develops in the lowercrust and is ascribed to the effect of partial melting of the crustal rocks., 北海道大学大学院理学研究院自然史科学部門（地球物理学）, Japanese
• Geomagnetic changes due to doming -The 2000 eruption of Usu volcano-
  Hashimoto, T; T. Mogi; Y. Nishida; M. Takada; A. Suzuki; T. Maekawa; H. Satoh, Geophysical Bulletin of Hokkaido University, 70, 70, 123, 135, 2007
  We investigated geomagnetic changes due to dome-like deformation by using a truncatedcircular cone model. In the case of the normal magnetization, magnetic total field decreasesin the northern side of the uplift center, while it increases in the southern side. We foundthat the original topography prior to the mound formation does not affect the pattern of thismagnetic change. We then apply this calculation to the mound-forming activity in the 2000eruption of Usu Volcano to infer the magnetic change on the foot of the mound. The expectedrange of magnetic total field change at the station U01 is -80 to -800 nT which is in theopposite sense to the observed actual change (+70 nT). We examined some alternativemechanisms to compensate this decrease due to the deformation. None of them, however,can be a promising candidate. The most reasonable explanation so far for this contradictionis the reversed magnetization of the Tertiary lava that may comprise the mound., 北海道大学大学院理学研究院自然史科学部門（地球物理学）, Japanese
• P92 Estimation of the volume change of the lake water at Nakadake crater 1, Aso volcano, Japan(THE VOLCANOLOGICAL SOCIETY OF JAPAN 2006 FALL MEETING)
  Terada Akihiko; Sasaki Satoshi; Hashimoto Takeshi; Kagiyama Tsuneomi; Saito Takeshi; Yoshikawa Shin, Programme and abstracts the Volcanological Society of Japan, 2006, 23 Oct. 2006
  Volcanological Society of Japan, Japanese
• 阿蘇中岳火口湯溜まりの水収支・熱収支再考(1991-2000)
  橋本武志; 池辺伸一郎, 日本火山学会講演予稿集, 2006, 2006
• 樽前火山山頂ドーム周辺におけるAMT比抵抗探査(2)
  山谷祐介; 橋本武志; 鈴木敦生; 市原寛; 長谷英彰; 渡辺朋典; 茂木透, 日本火山学会講演予稿集, 2006, 2006
• 小型ラマンライダーによる水蒸気の観測
  中村卓司; 杉本尚悠; 津田敏隆; 古本淳一; 阿保真; 橋本武志; 寺田暁彦, 日本気象学会大会講演予稿集, 89, 2006
• Seismic exploration at Fuji volcano with active sources: the outline of the experiment and the arrival time data
  Oikawa Jun; Kagiyama Tsuneomi; Tanaka Satoru; Miyamachi Hiroki; Tsutsui Tomoki; Ikeda Yasushi; Katayama Hiroaki; Matsuo Norimichi; Oshima Hiromitsu; Nishimura Yuichi; Yamamoto Keigo; Watanabe Toshiki; Yamazaki Fumihito; Watanabe Hidefumi; Fujii Toshitsugu; Nakada Setsuya; Takeo Minoru; Ohminato Takao; Kaneko Takayuki; Yoshimoto Mitsuhiro; Takeda Toyotarou; Koyama Etsurou; Osada Noboru; Saka Mamoru; Haneda Toshio; Hashimoto Shinichi; Tsuji Hiroshi; Imoto Yoshiko; Matsutani Fumio; Shimano Taketo; Furukawa Akiko; Sagiya Takeshi; Fujii Iwao; Hayashi Yoshinari; Miyajima Rikio; Yamada Mamoru; Okuda Takashi; Itoh Takeo; Hashimoto Takeshi; Maekawa Tokumitsu; Suzuki Atsuo; Itoh Taku; Miura Yasushi; Ueki Sadato; Nishimura Takeshi; Nita Kouichi; Satoh Mineji; Simomura Youichi; Nogami Kenji; Onizawa Sin'ya; Oyamada Hiroko; Funasaki Jun; Chikazawa Shin; Fujiwara Kenji; Hamada Nobuo; Aoki Gen; Takagi Akimichi; Yamamoto Tetsuya; Hayashi Yutaka; Kanao Masaki; Yamashita Mikiya; Shimizu Hiroshi; Watanabe Atsushi; Korenaga Masahiro; Ohkura Takahiro; Yoshikawa Shin; Ikeda Sayaka; Iguchi Masato; Tameguri Takeshi; Yakiwara Hiroshi; Hirano Shuichiro, Bulletin of the Earthquake Research Institute,University of Tokyo, 81, 1, 71, 94, 2006
  Fuji volcano (altitude 3,776m) is the largest basaltic stratovolcano in Japan. In late August and early September 2003, seismic exploration was conducted around Fuji volcano by the detonation of 500 kg charges of dynamite to investigate the seismic structure of that area. Seismographs with an eigenfrequency of 2 Hz were used for observation, positioned along a WSW-ENE line passing through the summit of the mountain. A total of 469 seismic stations were installed at intervals of 250-500 m. The data were stored in memory on-site using data loggers. The sampling interval was 4 ms. Charges were detonated at 5 points, one at each end of the observation line and 3 along its length. The first arrival times and the later-phase arrival times at each station for each detonation were recorded as data. P-wave velocities in the surface layer were estimated from the travel time curves near the explosion points, with results of 2.5 km/s obtained for the vicinity of Fuji volcano and 4.0 km5/s elsewhere., The University of Tokyo, Japanese
• NZ・ホワイトアイランド火山における高密度空中磁気観測
  宇津木充; 田中 良和; 橋本武志; Hurst Anthony White; 神田 径; 松島 健; 吉村令慧, 空中磁気測量による火山性磁場変動の検出(科学研究費補助金・基盤研究(B)研究成果報告書), 150, 162, 2006
  Japanese, Report research institution
• 雲仙火山の比抵抗構造から推定されるマグマからの脱ガス
  鍵山恒臣; スリグトモ ワヒュー; 橋本武志; 神田 径; 宗包浩志; 田中良和; 歌田久司; 清水久芳; 宇津木充; 小河 勉; 大湊隆雄, 第2回雲仙火山の集中総合観測報告書, 32, 44, 2006
  Japanese, Report research institution
• ホワイトアイランドにおける全磁力連続観測
  神田 径; 橋本武志; 田中良和; 宇津木充; 吉村令慧; ホワイト島火山空中磁気測量チーム, 空中磁気測量による火山性磁場変動の検出(科学研究費補助金・基盤研究(B)研究成果報告書), 49, 56, 2006
  Japanese, Report research institution
• B40 Self-potential Survey on Usu Volcano, 2006 Campaign(THE VOLCANOLOGICAL SOCIETY OF JAPAN 2006 FALL MEETING)
  Hase Hideaki; Hashimoto Takeshi; Nishida Yasunori; Utsugi Mitsuru; Inoue Hiroyuki, PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN, 2006, 0, 2006
  The Volcanological Society of Japan, Japanese
• P33 Magnetotelluric resistivity survey of Usu Volcano (project-2006)(THE VOLCANOLOGICAL SOCIETY OF JAPAN 2006 FALL MEETING)
  Hashimoto T; Koike T; Hasegawa H; fujii I; Yamaya Y; Ichihara H; Mogi T; Ogawa Y; Utsugi M; Inoue H; Takakura S; Satoh H, PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN, 2006, 0, 2006
  The Volcanological Society of Japan, Japanese
• 阿蘇火山中岳火口湯溜まりの水・熱・塩化物イオン収支
  SAITO TAKESHI; OSAWA SHINJI; HASHIMOTO TAKESHI; TERADA AKIHIKO; YOSHIKAWA SHIN; OKURA TAKAHIRO, 日本火山学会講演予稿集, 2006, 54, 2006
  Japanese
• Asama Volcano EM field experiments in 2005
  Hashimoto, T; T. Mogi; A. Suzuki; Y. Yamaya; M. Mishina; T. Nakatsuka; E. Koyama; T. Koyama; K. Aizawa; J. Hirabayashi; M. Matsuo; K. Nogami; Y. Ogawa; N. Ujihara; T. Kagiyama; W. Kanda; A. Okubo; Y. Tanaka; T. Uto; M. Utsugi, Conductivity Anomaly Research, 78, 79, 2006
  Japanese
• Apparent total field change due to secular variation -evaluation of volcanomagnetic effect-
  Hashimoto, T, Conductivity Anomaly Research, 51, 58, 2006
  Japanese
• Zeta-potential measurements of volcanic rocks
  Hashimoto, T; H. Hase; K. Satoh, report of grant-in-aid for scientific research (C) in Japan, 8, 16, 2006
  Japanese
• Repeated ground magnetic survey on White Island Volcano
  Hashimoto, T; W. Kanda; A.W. Hurst; M. Utsugi; R. Yoshimura; Aeromagnetic survey; team on White Island Volcano, report of grant-in-aid for scientific research (B) in Japan, 107, 140, 2006
  Japanese
• Long Valley Caldera -crustal activity in the recent decades-
  Hashimoto, T, Monthly Chikyu, 28, 2, 132, 139, 2006
  Japanese
• Electrical resistivity survey at the western part of Usu summit caldera - Subsurface structure of faults developed at the 2000 Usu volcano eruption
  Toru Mogi; Takeshi Hashimoto, Journal of the Hokkaido University, Faculty of Science, Series VII: Geophysics, 68, 233, 241, Mar. 2005
  Japanese, Book review
• 物理探査(地中レーダー,電気探査)による有珠山北麓の火山性断層調査
  田村慎; 岡崎紀俊; 大津直; 橋本武志; 茂木透, 日本火山学会講演予稿集, 2005, 2005
• 樽前火山山頂ドーム周辺におけるAMT比抵抗探査
  山谷祐介; 橋本武志; 鈴木敦生; 西田泰典; 市原寛; 茂木透; 渡辺朋典; 渡辺法夫, 日本火山学会講演予稿集, 2005, 2005
• 有珠火山の地磁気-簡易偏角・伏角測量-
  小野構大; 荻原弘尭; 梅原宏之; 橋本武志, 日本火山学会講演予稿集, 2005, 2005
• 御蔵島火山・やすかじが森溶岩ドーム山頂で真冬に白煙を上げる噴気孔類似の穴
  寺田暁彦; 日野正幸; 竹入啓司; 鈴木敦生; 橋本武志, 日本火山学会講演予稿集, 2005, 2005
• 火山岩石のゼータ電位測定
  長谷英彰; 石戸経士; 橋本武志; 神田径, 日本地熱学会学術講演会講演要旨集, 2005, A14, 2005
  Japanese
• 口永良部島火山における人工地震探査 —探査の概要と初動の走時について—(共著)
  井口正人; 山本圭吾; 橋本武志; 筒井智樹; 田中 聡; 鬼澤真也; 青木陽介; 渡辺俊樹; 大倉敬宏; 清水 洋; 八木原寛; 宮町宏樹; 平松秀行; 為栗 健; 高山鉄朗; 福嶋麻沙代; Hetty TRIASTUTY; 石原和弘; 大島弘光; 鈴木敦生; 前川徳光; 梶井達矢; 渡辺義明; 萩原庸平; 野上健治; 及川光弘; 平林順一; 辻 浩; 平田安廣; 奥田 隆; 伊藤 拓; 吉川 慎; 井上寛之; 池田さや香; 堀 美緒; 齊藤政城; 平野舟一郎; 上釜友大; 井口元治; 竹下孝弘; 森 健彦, 京都大学防災研究所年報, 48, B, 297, 322, 2005
• Wide-band MT Survey on Tarumai Volcano, Hokkaido: 2-D Resistivity Analysis
  Yamaya, Y; T. Hashimoto; T. Mogi; A. Suzuki; Y. Nishida, N; K. Tanimoto; H. Mori; A. Terada; M. Mishina; H. Hase, Geophysical bulletin of Hokkaido University, 68, 68, 127, 140, 2005
  北海道大学大学院理学研究科地球惑星科学専攻（地球物理学）, Japanese
• Seismic Exploration Using Active Sources at Kuchierabujima Volcano, Southwest Japan
  Iguchi Masato; Yamamoto Keigo; Hashimoto Takeshi; Tsutsui Tomoki; Tanaka Satoru; Onizawa Shin'ya; Aoki Yosuke; Watanabe Toshiki; Ohkura Takahiro; Shimizu Hiroshi; Yakiwara Hiroshi; Miyamachi Hiroki; Hiramatsu Hideyuki; Tameguri Takeshi; Takayama Tetsuro; Fukushima Masayo; Triastuty Hetty; Ishihara Kazuhiro; Oshima Hiromitsu; Suzuki Atsuo; Maekawa Tokumitsu; Kajii Tatsuya; Watanabe Yoshiaki; Ogiwara Yohei; Nogami Kenji; Oikawa Mitsuhiro; Hirabayashi Junichi; Tsuji Hiroshi; Hiratao Yasuhiro; Okuda Takashi; Itoh Taku; Yoshikawa Shin; Inoue Hiroyuki; Ikeda Sayaka; Hori Mio; Saito Masaki; Hirano Shuichiro; Uekama Yudai; Iguchi Motoharu; Takeshita Takahiro; Mori Takehiko, Bulletin of the Earthquake Research Institute,University of Tokyo, 80, 1, 11, 40, 2005
  Seismic exploration using artificial sources was conducted at Kuchierabujima volcano, southwest Japan in November 2004 by 40 participants from 9 national universities andJapan Meteorological Agency to investigate the subsurface seismic structure. The exploration was the 11th joint experiment under the National Project for Prediction of Volcanic Eruptions. A total of 183 temporal stations equippedwith a 2 Hz vertical component seismometer (including 75 3component seismometers) and a portable data logger were deployed on Kuchierabu Island. Dynamite shots with charges of 10-115 kg were detonated at 19 locations, and seismic signals were successfully recorded. To reveal the P-wave velocity structure, 2955 arrival times of the first motion were picked from the seismograms, and 2187 were classified into ranks A and B. From the record sections and the arrival time data, characteristics reflecting the geological structure were identified. Refracted waves of 5 km/s were observed at stations＞5km from the shot points. Apparent velocities near the shot points depend on the surface geology around the shots. P-wave arrived earlier at stations near the summits. Strongly scattered waves were observed similarly near the summits., The University of Tokyo, Japanese
• Electromagnetism for volcanology -history, significance and prospect-
  Hashimoto, T, Bull. Volcanol. Soc. Japan, 50, S115, S138, 2005
  The present paper summarizes the history of applied electromagnetism for field volcanology in Japan and abroad. Achievements are presented especially on volcanomagnetic effect, resistivity structure and its time change, and volcanoelectric effect, with a special attention to the social requirements for eruption prediction. Japan has been one of the leading countries in this research field in the past half century. In particular, geomagnetic filed measurement is recently attracting a growing interest as a regular and standard item for volcano monitoring in this country. Other electric or electromagnetic methods, such as resistivity sounding or selfpotential, have also contributed to reveal shallow processes involving volcanic fluids beneath active volcanoes preceding, during, and after their eruptions. The author also proposes some future directions in developing measurement techniques to improve the spatial coverage, resolution, depth penetration as well as to seek for safer data acquisition., Volcanological Society of Japan, Japanese
• Zeta potential measurements of rock samples (Takano-obane lava) from a boring core
  Hase, H; T. Ishido; T. Hashimoto; K. Furukawa, Conductivity Anomaly Research, 48, 53, 2005
  Japanese
• 九州の4火山(開聞岳・九重山・猿葉山・雲仙岳)の岩石のゼータ電位測定 (地殻活動電磁気学1--火山活動の場)
  長谷 英彰; 石戸 経士; 橋本 武志, Conductivity anomaly研究会論文集, 25, 32, 2004
  CA研究グループ, Japanese
• 草津白根火山における高密度電気探査・自然電位調査--2003年度集中総合観測 (地殻活動電磁気学1--火山活動の場)
  橋本 武志; 茂木 透; 西田 泰典, Conductivity anomaly研究会論文集, 46, 54, 2004
  CA研究グループ, Japanese
• 電磁気観測による北海道南西部3火山の火山体構造(1)
  山谷祐介; 茂木透; 橋本武志, 日本火山学会講演予稿集, 2004, 2004
• 火山噴火に伴う熱水対流系変化の電磁気モニタリング-数値モデルに基づく定量的検討-
  佐波瑞恵; 茂木透; 橋本武志; 西田泰典; 鈴木敦夫; 高倉伸一; 松島喜雄, 日本火山学会講演予稿集, 2004, 2004
• 自然電位と岩石のゼータ電位を利用した地質構造の推定
  長谷英彰; 石戸径士; 橋本武志; 長谷中利昭; 三好雅也, 日本火山学会講演予稿集, 2004, 2004
• 有珠山西山西麓火口域の地磁気変化
  橋本武志; 赤間秀俊; 前川徳光; 鈴木敦生; 茂木透; 山谷祐介; 西田泰典, 日本火山学会講演予稿集, 2004, 2004
• 地磁気および自然電位による火山爆発場の観測的研究
  神田 径; 田中良和; 宇津木 充; 橋本武志; 北田直人; 後藤秀作; 大野正夫, 火山爆発のダイナミックス平成15年度研究成果報告書, 67, 74, 2004
  Japanese, Report research institution
• Resistivity Structure of Hokkaido Komagatake Volcano using Wide Band MT Method : The Result of 1D Inversion and Estimation of Influences of the Ocean
  Yamaya, Y; K. Tanimoto; Y. Nishida; M. Saba; M. Miyahara; K. Yoshida; T. Mogi; T. Hashimoto, Geophysical bulletin of Hokkaido University, 67, 39, 51, 2004
  北海道大学大学院理学研究科地球惑星科学専攻（地球物理学）, Japanese
• High-density electrical sounding and self-potential profiling at Kusatsu-Shirane volcano
  Hashimoto, T; T. Mogi; Y. Nishida; Y. Ogawa; J. Hirabayashi, M; Oikawa; M. Saito; M. Mizuhashi; N. Ujihara; Nurhasan; T. Wakabayashi, Report of the 4th Joint Observation of Kusatsu-Shirane Volcano, 133, 142, 2004
  Japanese
• Self-potential studies in volcanic areas (5) -Rishiri, Kusatsu-Shirane, and White Island-
  Hashimoto, T; T. Mogi; Y. Nishida; Y. Ogawa; N. Ujihara; M. Oikawa; M. Saito; Nurhasan; S. Mizuhashi; T. Wakabayashi; R. Yoshimura; A. W. Hurst; M. Utsugi; Y. Tanaka, J. Fac. Sci. Hokkaido Univ., Ser. VII, 12, 2, 97, 113, 2004
  Hokkaido University, English
• PRELIMINAR Y RESULTS OF WIDE -BAND MAGNETOTELLURIC SOUNDING IN FUJI VOLCANO, JAPAN
  HURST Tony; TANK S.Bulent, 京都大学防災研究所年報. B = Disaster Prevention Research Institute Annuals. B, 46, 0, 729, 737, 01 Apr. 2003
  2002年9月, 富士山周辺で広帯域 MT観測を行なった。その結果, 富士山直下深部に低抵抗体が存在することが強く示唆された。現在のところ, データの量, 質とも不十分なため, その低抵抗体の深さや広がりは不明である。しかし予備的な解析によると, 低抵抗体の深さの上面は, 深さ 15キロの深部低周波地震の発生領域と一致するために, マグマ溜りを表している可能性がある。また得られたデータには顕著な異方性が見られる。Wide-band MT soundings in Fuji volcano were carried out September, 2002. Collected data suggestsexistence of low resistivity anomaly deeper part beneath Fuji volcano. A two dimensional inversioncode was applied to data. Preliminary result show that low resitivity body locates at a depth about15-20km which consists with hypo central region of deep low frequency earthquake. This lowresistivity body may be a magma chamber., 京都大学防災研究所, Japanese
• 地磁気からみた口永良部島火山の蓄熱場
  神田 径; 田中良和; 宇津木 充; 藤井郁子; 橋本武志, 地球惑星科学関連学会2003年合同大会予稿集, 2003
  Japanese, Report research institution
• Hydrothermal system inferred from self-potential survey on Tsurumi-dake volcano
  Hashimoto, T; K. Amita; H. Hase; Y. Tanaka, Hotspring Research Report, Ohita Prefecture, 54, 54, 91, 96, 2003
  大分県温泉調査研究会, Japanese
• On the annual variations in geomagnetic differences observed in Long Valley Caldera, California
  Hashimoto, T; Y. Tanaka; M. J; S. Johnston; M. Utsugi; Y. Sasai; S. Sakanaka, Annuals. Disast. Prev. Res. Inst., Kyoto Univ., 46, B, 765, 777, 2003
  京都大学防災研究所, Japanese
• Quantitative Models for Geomagnetic Changes Associated with the 2000 Activity of Miyake-jima Volcano
  SASAI Y; UYESHIMA M; UTADA H; KAGIYAMA T; ZLOTNICKI J; HASHIMOTO T; TAKAHASHI Y, Programme and abstracts the Volcanological Society of Japan, 2002, 2, 22 Oct. 2002
  Volcanological Society of Japan, Japanese
• Magnetic field changes during the caldera formation of Miyake-jima in 2000
  Sugioka Manabu; Kagiyama Tsuneomi; Sasai Youichi; Uyeshima Makoto; Hashimoto Takeshi, Programme and abstracts the Volcanological Society of Japan, 2002, 2, 22 Oct. 2002
  Volcanological Society of Japan, Japanese
• Measurement of vertical geoelectrical potential difference using a borehole near Unzen volcano
  OGAWA Tsutomu; KAGIYAMA Tsuneomi; TANAKA Yoshikazu; HASHIMOTO Takeshi; HASE Hideaki, Programme and abstracts the Volcanological Society of Japan, 2002, 2, 22 Oct. 2002
  Volcanological Society of Japan, Japanese
• 九重火山におけるラピッドスタティック法を用いたちゅう密GPS測量
  中坊真; 小野博尉; 橋本武志; 大倉敬宏; 須藤靖明; 吉川慎; 宇津木充; 坂中伸也; HURST A W, 日本火山学会講演予稿集, 2002, 107, 107, 22 Oct. 2002
  The Volcanological Society of Japan, Japanese
• 地磁気変化を利用した地熱の推移に関する研究(2)
  田中 良和; 宇津木 充; 橋本 武志, 大分県温泉調査研究会報告, 53, 57, 63, Jul. 2002
  大分県温泉調査研究会, Japanese
• 1998Seismic Exploration, ASO98, in AsoVolcano
  Sudo Yasuaki; Tsutsui Tomoki; Ono Hiroyasu, Bulletin of the Earthquake Research Institute, University of Tokyo, 77, 4, 303, 336, 2002
  A seismic exploration, ASO98, was conducted in Aso Volcano in central Kyushu, Japan. The purpose of this exploration was both to obtain the detailed seismic structures beneath the central cones and to detect the kinematic character of volcanic tremors of Aso Volcano. Six shot points with chemical explosions and a temporary network with 296 seismic stations were deployed over the central cones in a range of 10 km east-west by 9 km north-south. All explosions were completed on 26 November, 1998, and seismic records were successfully acquired at each of 290 stations. This paper reports on the details of ASO98, such as examples of acquired seismic traces for shots, locations of stations and shots, Final first arrival times, amplitude distributions, and examples of records acquired of volcanic tremors. These data are expected to provide much knowledge about volcanic seismology and about Aso Volcano. Further analyses will be described in forthcoming papers., The University of Tokyo, Japanese
• Shallow Structure of the Central Cones of Aso Volcano Inferred from Electromagnetic Explorations
  Hashimoto, T; Y. Tanaka; K. Amita; S. Takakura; W. Kanda; S. Sakanaka; T. Kagiyama, report of grant-in-aid for scientific research in Japan, 2002
  Japanese
• Ground Deformation at Kuju Volcano
  Nakaboh, M; H. Ono; M. Sako; T. Hashimoto; Y. Sudo; T. Ohkura; S. Yoshikawa; M. Utsugi; S. Sakanaka; A. W. Hurst, Annuals. Disast. Prev. Res. Inst., Kyoto Univ., 45, B, 633, 644, 2002
  Japanese
• Measurement of zeta-Potential in Various Rock Samples of Aso Volcano
  Hase, H; S Takakura; T. Ishido; K. Sato; T. Hashimoto; Y. Tanaka; T. Ohkura, Annuals. Disast. Prev. Res. Inst., Kyoto Univ., 45, B, 645, 656, 2002
  京都大学防災研究所, Japanese
• Heat Discharging Process and Geomagnetic Changes of Iwoyama, Kuju, Volcano
  Hashimoto, T; M. Utsugi; S. Sakanaka; Y. Tanaka, Annuals. Disast. Prev. Res. Inst., Kyoto Univ., 45, B, 617, 625, 2002
  Japanese
• Preliminary Report on the 2001 Wide-band Magnetotelluric Sounding of Deep Crustal Resistivity Structure in and around the Focal area of the 2000 Tottori-ken Seibu Earthquake, Japan
  The; Research Group for Crustal Resistivity Structure, Annuals. Disast. Prev. Res. Inst., Kyoto Univ., 45, B, 489, 497, 2002
  Japanese
• ロングバレーカルデラにおける地磁気観測
  田中良和; 宇津木充; 橋本武志; 笹井洋一; 上嶋誠; 後藤忠徳; 坂中伸也; JONSTON M; ZLOTONICKI J, 日本火山学会講演予稿集, 2001, 70, 01 Oct. 2001
  Japanese
• 阿蘇火山中岳火口湯だまりの水位変動と放熱量について
  橋本武志; 池辺伸一郎; 田中良和; 小野博尉; 中坊真, 日本火山学会講演予稿集, 2001, 2001
• 九重火山における噴気圧力振動の測定
  鈴木隆; 吉川美由紀; 森健彦; 平林順一; 大場武; 須藤靖明; 橋本武志; 迫幹男; LONDONO J, 日本火山学会講演予稿集, 2001, 2001
• Heat discharge, water level and geomagntic variation observed at Aso Nakadake Volcano
  橋本武志; 田中良和; 宇津木充; 池辺伸一郎, 地球電磁気・地球惑星圏学会総会及び講演会予稿集(CD-ROM), 110th (Web), 2001
• Geomagnetic variation observed at Aso Volcano during the past ten years
  Hashimoto, T; Y. Tanaka; M. Utsugi, Annuals. Disast. Prev. Res. Inst., Kyoto Univ., 44, B-1, 333, 343, 2001
  京都大学防災研究所, Japanese
• Cooling Shape of Vents beneath Fumaroles at Kuju-Iwoyama Inferred from Geomagnetic Changes by Repeated Surveys
  Sakanaka, S; Y. Tanaka; M. Utsugi; T. Hashimoto, Scientific and Technical Reports of Faculty of Engineering and Resource Science., Akita Univ., 22, 25, 38, 2001
  Geothermal changes in the subsurface volcanic and geothermal areas can be inferred from monitoring thegeomagnetic changes. We installed several proton precession magnetometers for continuous observation andset up tens of observation sites for repeated survey in the geothermal area at Kuju-Iwoyama, Kyushu Island,Southwest of Japan, after the vapor eruption (phreatic explosion) event in October of 1995. So far, we carriedout repeated surveys three times - in March to April of 1999, August to September of 1999, and Decemberof 1999 to January of 2000 for more than 30 sites. Geomagnetic changes in the total force close to 40nTjyearwere observed at some observation sites during less than one year. The amounts of changes obtained by therepeated surveys were consistent with those obtained by the continuous observations.In this study we indicate that installing a number of sites for repeated survey made it possible to revealthe shape of cooling or heating bodies to some extent. An inclined and cone-shaped cooling body beneathmajor fumaroles is inferred at Kuju-Iwoyama., Akita University, Japanese
• Heat discharging process and shallow structure of Aso Nakadake crater as inferred from geomagnetic changes
  Hashimoto, T, Proceedings of the research meeting "Volcanic Structure in the Shallow Part and Volcanic Fluid", 149, 159, 2001
  Japanese
• 三宅島火山2000年活動における電磁気観測
  笹井洋一; 上嶋誠; 歌田久司; 高橋優志; ZLOTNICKI J; 橋本武志; 宇津木充; 田中良和; 谷元健剛, 日本火山学会講演予稿集, 2000, 2000
• Self-potential measurements on the central cones of Aso Volcano
  Hase, H; Y. Tanaka; T. Hashimoto; S. Sakanaka, Annauls. Disast. Prev. Res. Inst., Kyoto Univ., 43, B-1, 47, 53, 2000
  Japanese
• Resistivity sections of the Aso caldera, central Kyushu, Japan, inferred from magnetotelluric soundings
  Takakura, S; T. Hashimoto; K. Koike; Y. Ogawa, Conductivity Anomaly Research, 23, 30, 2000
  Japanese
• Electromagnetic observation during water injection experiment (2)
  Murakami, H; T. Hashimoto; N. Oshiman; S. Yamaguchi, Chikyu Monthly, 23, 250, 255, 2000
  Japanese
• Ground deformation associated with geothermal activity at Kuju Volcano
  NAKABOH M.; ONO H.; SAKO M.; HASHIMOTO T.; SUDO Y., 日本地熱学会学術講演会講演要旨集, 1999, 01 Dec. 1999
  Japanese
• Resistivity Structure of Deep Geothermal System in the Aso Caldera, Central Kyushu, Japan
  TAKAKURA T.; HASHIMOTO T.; KOIKE K.; OGAWA Y., 日本地熱学会学術講演会講演要旨集, 1999, 01 Dec. 1999
  Japanese
• 桜島における高密度電気探査
  茂木透; 橋本武志; 神田径; 田中良和; 山本圭吾; 大羽成征; 大島弘光; 佐波瑞恵; 平林順一, 日本火山学会講演予稿集, 1999, 53, 09 Oct. 1999
  Japanese
• Resistivity Structure of Aso Volcano in Japan(1)
  AMITA K.; HASHIMOTO T.; MASUDA H.; MORI T.; NAKABOU M.; YAMAMOTO M.; KAWAKATSU H.; IDE S.; KANESHIMA S.; OHMINATO T., 日本地熱学会誌, 21, 1, 76, 76, 25 Jan. 1999
  Japanese
• 阿蘇山における自然電位観測
  長谷英彰; 田中良和; 橋本武志; 坂中伸也, 日本火山学会講演予稿集, 1999, 1999
• A TDEM experiment for revealing electrical image of Aso Volcano, Japan
  Kanda W; Mogi T; Munekane H; Ogawa T; Ono H; Sakanaka S; Shimoizumi M; Tanaka Y; Widarto D. S; Amita K; Handa S; Hase H; Hashimoto T; Ikoma Y; Kagiyama T; Koyama T; Masuda H, PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN, 1999, 0, 134, 134, 1999
  The Volcanological Society of Japan, Japanese
• Electrical structure of Aso Volcano inferred from bipole-dipole method
  Hashimoto T; Mogi T; Munekane H; Ogawa T; Ono H; Sakanaka S; Shimoizumi M; Tanaka Y; Djedi S. W; Amita K; Handa S; Hase H; Ikoma Y; Kagiyama T; Kanda W; Koyama T; Masuda H, PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN, 1999, 0, 1999
  The Volcanological Society of Japan, Japanese
• Electroseismic changes observed at an explosion experiment in Aso Volcano
  Hase, H; Y. Tanaka; T. Hashimoto; S. Sakanaka; T. Mori; H. Masuda; S. Yoshikawa, Conductivity Anomaly Research, 193, 200, 1999
  Japanese
• Self-potential surveying of Suwanosejima Volcano
  Kanda, W; T. Hashimoto; H. Oshima, Annuals. Disast. Prev. Res. Inst., Kyoto Univ., 42, B-1, 11, 18, 1999
  京都大学防災研究所, Japanese
• Self-potential on the central cones of Aso Volcano (1)
  Tanaka, Y; T. Hashimoto; H. Hase; S. Sakanaka; H. Masuda, Conductivity Anomaly Research, 187, 192, 1999
  Japanese
• Network-MT Survey in Kyushu Island, Southwestern Japan
  Hashimoto, T; K. Amita; H. Mawatari; Y. Tanaka, Conductivity Anomaly Research, 1999, 29, 37, 1999
  CA研究グル-プ, Japanese
• Self-potential and Hydrothermal System in Sakurajima Volcano (2)
  Hashimoto, T; Y. Tanaka; Y. Nishida; T. Mogi; K. Yamamoto; W. Kanda; J. Hirabayashi; K. Ishihara, Annuals. Disast. Prev. Res. Inst., Kyoto Univ., 42, B-1, 19, 25, 1999
  京都大学防災研究所, Japanese
• High-density DC electrical resistivity survey on Sakurajima Volcano
  Mogi, T; T. Hashimoto; W. Kanda; Y. Tanaka; K. Yamamoto; S. Ohba; H. Oshima; M. Saba; J. Hirabayashi, report of cooperative research in Disaster Prevention Research Institute, Kyoto University, 9P-5, 103, 108, 1999
  Japanese
• Selfpotential and magnetic total field surveys on Suwanose-jima volcano
  Kanda, W; S. Mori; T. Hashimoto; H. Oshima, report of the 3rd Joint Observation of Suwanose-jima Volcano, 41, 53, 1999
  Japanese
• Self-poteitial on Sakurajima Volcano
  Hashimoto, T; Y. Tanaka; Y. Nishida; T. Mogi; K. Yamamoto; J. Hirabayashi; K. Ishihara, report of cooperative research in Disaster Prevention Research Institute, Kyoto University, 65, 101, 1999
  Japanese
• Leveling Survey at Aso Volcano (III)
  Nakaboh M.; Sudo Y.; Tsutsui T.; Yoshikawa M.; Garces M.; Tanaka Y.; Nishijima J.; Yoneshige K.; Kawaguchi M.; Kudou T.; Fujimitsu Y.; Sako M.; Yoshikawa S.; Masuda H.; Hoka T.; Hashimoto T.; Diago J. C.; Hase H.; Ono H., PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN, 1998, 0, 64, 64, 1998, [Peer-reviewed]
  The Volcanological Society of Japan, Japanese
• Gravity Measurements at Aso Volcano
  Yoshikawa Shin; Mori Takehiko; Masuda Hideharu; Sako Mikio; Hoka Teruaki; Hashimoto Takeshi; Tsutsui Tomoki; Sudo Yasuaki, PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN, 1998, 0, 117, 117, 1998, [Peer-reviewed]
  The Volcanological Society of Japan, Japanese
• 伊東市周辺における比抵抗構造調査
  神田 径; 笹井洋一; 歌田久司; 鍵山恒臣; 小山 茂; 小山崇夫; 宗包浩志; 上嶋 誠; 田中良和; 橋本武志; 長谷英彰; 清水久芳; 小河 勉; 網田和宏; 馬渡秀夫, 第104回地球電磁気・地球惑星圏学会講演会講演予稿集, B41-06, 1998
  Japanese, Report research institution
• Electromagnetic observations during the water injection experiment at Nojima fault
  Murakami, H; T. Hashimoto; N. Oshiman; N. Sumitomo; S. Yamaguchi; Y. Honkura, Conductivity Anomaly Research, 209, 216, 1998
  Japanese
• Electromagnetic observations during the water injection experiment at Nojima fault
  Murakami, H; T. Hashimoto; N. Oshiman; N. Sumitomo; S. Yamaguchi; Y. Honkura, Monthly Chikyu, S21, 54, 58, 1998
  Japanese
• Network-MT measurements in Kyushu island
  Tanaka, Y; K. Amita; S. Oba; H. Mawatari; T. Hashimoto; M. Shimoizumi; Y. Sasai, Conductivity Anomaly Research, 243, 253, 1998
  Japanese
• Resistivity structure of Aso caldera inferred from Magnetotelluric measurements (preliminary)
  Takakura, S; T. Hashimoto; Y. Ogawa; T. Nishigaki, Conductivity Anomaly Research, 225, 232, 1998
  Japanese
• Resistivity survey around Nojima fault using earth current
  Hashimoto, T, Monthly Chikyu, S21, 82, 86, 1998
  Japanese
• Self-potential and hydrothermal system of the western part of Sakurajima Volcano
  Hashimoto, T; Y. Tanaka; T. Mogi; Y. Nishida; S. Oba; K. Yamamoto; K. Ishihara, Annuals. Disast. Prev. Res. Inst., Kyoto Univ., 41, B-1, 145, 151, 1998
  京都大学防災研究所, Japanese
• Self-potential measurements on Sakurajima Volcano
  Hashimoto, T; Y. Tanaka; S. Oba; Y. Nishida; K. Tanimoto; M. Utsugi; T. Mogi; K. Yamamoto; K. Ishihara; A. Yamazaki; N. Ito; T. Ikegame, report of the 9th observation project of Sakurajima Volcano, 71, 78, 1998
  Japanese
• Electric Potential Changes Associated with a Water Injection Experiment at Nojima Fault
  HASHIMOTO T.; OSHIMAN N.; SUMITOMO N.; MURAKAMI H.; YAMAGUCHI S.; HONKURA Y., 日本地震学会講演予稿集 = Programme and abstracts, the Seismological Society of Japan, 1997, 2, 15 Sep. 1997
  Japanese
• Activity of Kuju volcano through November 1996 to March 1997.
  須藤靖明; 小野博尉; 筒井智樹; 橋本武志; 森健彦; 松本良浩; 中坊真; 増田秀晴; 吉川慎, 地球惑星科学関連学会合同大会予稿集, 1997, 1997
• Self-Potential Mapping in Sakurajima Volcano. (1).
  橋本武志; 田中良和; 大羽成征; 西田泰典; 茂木透; 谷元健剛; 山本圭吾; 石原和弘, 日本火山学会講演予稿集, 1997, 1997
• Self-potential variations associated with volcanic eruptions
  Hashimoto, T, Conductivity Anomaly Research, 16, 20, 1997
  Japanese
• Self-potential Mapping in Kuji Volcanoes.
  橋本武志; 田中良和; 大羽成征; 茂木透, 日本火山学会講演予稿集, 1996, 2, 05 Nov. 1996
  特定非営利活動法人日本火山学会
• Self-potential survey in Garandake volcano.
  大羽成征; 田中良和; 由佐悠紀; 橋本武志, 日本火山学会講演予稿集, 1996, 2, 05 Nov. 1996
  特定非営利活動法人日本火山学会
• Monitoring of Geomagnetic Field and Self-potential in Kuju Volcanoes.
  田中良和; 橋本武志; 増田秀晴; 大羽成征; 茂木透, 日本火山学会講演予稿集, 1996, 2, 05 Nov. 1996
  特定非営利活動法人日本火山学会
• Deformation associated with recent activity of Kuju volcano.
  中坊真; 西潔; 小野博尉; 迫幹雄; 須藤靖明; 橋本武志, 日本火山学会講演予稿集, 1996, 1996
• Seismic Observation around A Mud Volcano in Tsukahara Mine, Beppu : As A Small Size Example for Volcanic Tremor
  Nakaboh M.; Yusa Y.; Kitaoka K.; Ohsawa S.; Mawatari H.; Oue K.; Mori T.; Kobayashi Y.; Sudo Y.; Tsutsui T.; Hashimoto T.; Yoshikawa S.; Matsumoto Y.; Tanaka M., PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN, 1996, 0, 112, 112, 1996, [Peer-reviewed]
  The Volcanological Society of Japan, Japanese
• Volcanic actibity in Kuju volcano
  nakaboh M.; Oba S.; Tanaka M.; Sako M.; Hoka T.; Masuda H.; Yamada T.; yoshikawa S.; Kobayashi Y.; Mogi T.; Hashimoto T.; Sudo Y.; Tutui T.; Ono H.; Tanaka Y.; Kikuchi S.; Mori T.; Matumoto Y., PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN, 1996, 0, 173, 173, 1996, [Peer-reviewed]
  The Volcanological Society of Japan, Japanese
• 日光地域におけるMT観測
  大谷冬彦; 本蔵義守; 松島政貴; 黒木英州; 小川康雄; 光畑裕司; 大志万直人; 坂中伸也; 橋本武志, Conductivity Anomaly研究会1996年論文集, 121, 127, 1996
• Self-potential as an indicator of hydrothermal activity - A case study in 1990-1995 eruption of Unzen Volcano -
  Hashimoto, T, Conductivity Anomaly Research, 222, 229, 1996
  Japanese
• Research on subsurface hydrothermal system using self-potential method
  Tanaka, Y; T. Hashimoto; T. Kagiyama; H. Utada, Research Report of Earthq. Res. Inst., University of Tokyo, 12, 7, 9, 1996
  Japanese
• Electromagnetic Stdies in Kuju-Iwoyama Volcano
  Tanaka, Y; T. Mogi; T. Hashimoto; H. Masuda; T. Yukutake; S. Oba, report of grant-in-aid for scientific research in Japan, 125, 140, 1996
  Japanese
• Dense seismic network in crater vicinity of Mt. Nakadake, Aso Volcano.
  森健彦; 須藤靖明; 筒井智樹; 吉川慎; 迫幹雄; 外輝明; 松本良浩; 中坊真; 橋本武志, 日本地震学会秋季大会講演予稿集, 1995, 1995
• Self-Potential Observation on Unzen Volcano.
  橋本武志; 田中良和, 日本火山学会講演予稿集, 1995, 1995
• Dense seismic network in crater vicinity of Mt. Nakadake, Aso Volcano
  Mori T.; Sudo Y.; Tsutsui T.; Yoshikawa S.; Sako M.; Hoka T.; Matsumoto Y.; Nakaboh M.; Hashimoto T., PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN, 1995, 0, 96, 96, 1995, [Peer-reviewed]
  The Volcanological Society of Japan, Japanese
• 島原半島におけるネットワークMT法観測について (文部省S)
  上嶋誠; 歌田久司; 鍵山恒臣; 田中良和; 橋本武志; 増田秀晴; 松島健, 雲仙岳における火山体構造探査の事前調査研究 平成6年度 No.06306011, 69, 73, 1995
  Japanese
• Self-potential measurement on the crater lake of Kirishima-Shinmoedake Volcano
  Hashimoto, T; Y. Honkura; F. Ohtani, Conductivity Anomaly Research, 23, 30, 1995
  Japanese
• Searching the conduit of Unzen Volcano using self-potential anomalies
  Hashimoto, T; Joint Research Group of; Universities for; Unzen Volcano, report of grant-in-aid for scientific research in Japan, 80, 86, 1995
  Japanese
• VOLCANO-MAGNETIC EFFECTS ON THE UNZEN VOLCANO (1991-1993)
  田中 良和; 橋本 武志; 増田 秀晴; 吉川 慎; 大学合同観測班, 京都大学防災研究所年報, 37, p193, 206, Apr. 1994
  京都大学防災研究所, Japanese
• Geomagnetic Changes on the Unzen Volcano (1991-94).
  田中良和; 橋本武志; 増田秀晴, 日本火山学会講演予稿集, 1994, 1994
• Self-potential Survey of Izu-Oshima Volcano in 1994.
  石戸経士; 松島喜雄; 矢野雄策; 中尾信典; 菊地恒夫; 光畑裕司; 内田利弘; 橋本武志, 日本火山学会講演予稿集, 1994, 1994
• Subsurface hydrothermal system inferred from the self-potential and the ground resistivity in Unzen volcano.
  橋本武志; 田中良和, 日本火山学会講演予稿集, 1994, 1994
• On electrode as a sensor
  Hashimoto, T, Conductivity Anomaly Research, 86, 97, 1994
  Japanese
• Self-potential measurements in volcanic fields
  Hashimoto, T; Y. Tanaka; Y. Sudo, Annuals Disast. Prev. Res. Inst., Kyoto Univ., 37, B1, 183, 191, 1994
  京都大学防災研究所, Japanese
• Volcanic activity and self-potential field of Unzen Volcano
  Hashimoto, T; Joint Research Group of; Universities for; Unzen Volcano, report of grant-in-aid for scientific, research in Japan, 90, 102, 1994
  Japanese
• MT Survey Around Shinmoe-dake, Kirishima Volcanoes
  INOUE Tomohiro; MOTOKI Tomohiro; UTADA Hisashi; KAGIYAMA Tsuneomi; MASUTANI Fumio; YAMAGUCHI Masaru; HASHIMOTO Takeshi, Programme and abstracts the Volcanological Society of Japan, 1993, 2, 04 Oct. 1993
  Volcanological Society of Japan, Japanese
• Spatial distribution of self-potential measured around the crater of Shinmoe-Dake, Kirishima volcanoes
  HASHIMOTO Takeshi; TANAKA Yoshikazu; KAGIYAMA Tsuneomi; MASUTANI Fumio, Programme and abstracts the Volcanological Society of Japan, 1993, 2, 04 Oct. 1993
  Volcanological Society of Japan, Japanese
• Spatial distribution of apparent resistivity around Unzen Volcano revealed by the Network-MT method
  Uyeshima M; Utada H; Kagiyama T; Hashimoto T; Tanaka Y; Magnetotelluric Research; Group of; Unzen Volcano, Programme and abstracts the Volcanological Society of Japan, 1993, 2, 04 Oct. 1993
  Volcanological Society of Japan, Japanese
• Hydrothermal convection inferred from self-potential measurements
  Hashimoto, T; Y. Tanaka; H. Masuda; H. Utada; T. Kagiyama; F. Masutani, Conductivity Anomaly Research, 249, 255, 1993
  Japanese
• Observations of Self-Poteitial on Unzen Volcano
  Hashimoto Takeshi; Tanaka Yoshikazu; Masuda Hideharu; Utada Hisashi; Kagiyama Tsuneomi; Masutani Fumio, Programme and abstracts the Volcanological Society of Japan, 1992, 2, 33, 33, 09 Nov. 1992
  Volcanological Society of Japan, Japanese
• Volcanomagnetic changes on Aso (1989-1992)
  TANAKA Yoshikazu; HASHIMOTO Takeshi; MASUDA Hideharu, PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN, 1992, 85, 85, 1992
  The Volcanological Society of Japan, Japanese
• Simultaneous Observation of Atmospheric Electric Field Strength and Specific Charge of Ash
  Miura T.; Koyaguchi T.; Tanaka Y.; Hashimoto T., PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN, 1992, 82, 82, 1992
  The Volcanological Society of Japan, Japanese
• Self-potential measurements on Unzen volcano in 1991
  Hashimoto, T; Y. Tanaka; H. Masuda; H. Utada; T. Kagiyama; F. Masutani, Conductivity Anomaly Research, 1992, 249, 256, 1992
  Japanese
• MT Survey in and Around the Volcanoes Unzen
  KAGIYAMA Tsuneomi; UTADA Hisashi; MASUTANI Fumio; YAMAMOTO Tetsuya; MURAKAMI Hideki; MASUDA Hideharu; HASHIMOTO Takeshi; TANAKA Yoshikazu, Programme and abstracts the Volcanological Society of Japan, 1991, 2, 152, 152, 14 Oct. 1991
  Volcanological Society of Japan, Japanese
• Geomagnetic Changes Related with the Eruption of Unzen Volcano in 1991
  Tanaka Y.; Hashimoto T.; Masuda H.; Handa S.; Utada H., PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN, 1991, 24, 24, 1991
  The Volcanological Society of Japan, Japanese

• Volcanic Lakes
  Hurst T; Hashimoto T; Terada A, Crater Lake Energy and Mass Balance
  Springer, 2015, [Contributor]
• 日本地方地質誌1 北海道地方
  西田泰典; 橋本武志, 10.5 北海道における地殻，上部マントルの熱的構造
  朝倉書店, Nov. 2010, [Contributor]
• The Sun-Earth system science
  HASHIMOTO Takeshi, Chapter 10: Magnetic field of the Earth
  京都大学学術出版会, May 2010, [Joint work]

• Trial application of the volcanic unrest index (VUI) to Mt Meakandake
  Hashimoto, T.; Aoyama, H.; Tanaka, R.; Ohkura, T.; Mori, T.; Takagi, A.
  Volcanological Society of Japan, 16 Oct. 2024, Japanese, Poster presentation
  16 Oct. 2024 - 18 Oct. 2024
• Conductivity anomalies in the deep subsurface of central Hokkaido
  Hashimoto, T.; J. Pan; A. Suzuki; M. Takada; K. Okada; R. Tanaka; M. Tamura
  26th EM Induction Workshop, 08 Sep. 2024, English, Poster presentation
  07 Sep. 2024 - 13 Sep. 2024
• Deep Three-Dimensional Electrical Conductivity Structure of Mt. Tokachi and Its Surrounding, Central Hokkaido, Japan
  Juohua Pan; Takeshi Hashimoto; Ryo Tanaka; Atsuo Suzuki; Masamitsu Takada; Kazumi; Okada; Makoto Tamura
  Japan Geoscience Union, 26 May 2024, English, Oral presentation
  24 May 2024 - 29 May 2024
• Volcanomagnetic changes associated with expanding geothermal anomalies at Mt Tokachidake
  Hashimoto, T.; Aoyama, K.; I, T.; Tsukagawa, K.; Yamazaki, Y.
  Volcanological Society of Japan, 18 Oct. 2023, Japanese, Oral presentation
  18 Oct. 2023 - 20 Oct. 2023
• Repeated aeromagnetic survey aiming for monitoring the volcanomagnetic effects and 3D imaging of the magnetization changes
  Hashimoto T; K Shibuya
  IAVCEI, 30 Jan. 2023, English, Poster presentation
• Persistent cooling remagnetization beneath the summit crater of Usu Volcano
  Hashimoto, T
  The Volcanological Society of Japan, 18 Oct. 2022, Japanese, Poster presentation
• A t rial application of the Volcanic Unrest Index (VUI) to Mt. Tokachidake
  Hashimoto, T; H Aoyama; R Tanaka; T Ohkura; T Mori
  日本火山学会, 09 Oct. 2020, Japanese, Oral presentation
• From monitoring to forecasting -Toward statistical evaluation of non-magmatic unrest-
  HASHIMOTO Takeshi
  International Workshop on the mechanism of Phreatic Eruption, 16 Jan. 2020, English, Invited oral presentation
  15 Jan. 2020 - 16 Jan. 2020, [Invited]
• 噴気画像の自動処理
  日本火山学会秋季大会, 25 Sep. 2019, Japanese, Poster presentation
  25 Sep. 2019 - 27 Sep. 2019
• Source characteristics of demagnetization and ground deformation during inter-eruptive periods
  Hashimoto T; Utsugi M; Ohkura T; Kanda W; Terada A; Miura S; Iguchi M
  International Union of Geodesy and Geophysics, 16 Jul. 2019, English, Oral presentation
  [International presentation]
• Simple and Fast Method to Remove Volcanic Smoke in Visible and TIR Imagery
  Hashimoto T; Terada A; Tanaka R
  International Union of Geodesy and Geophysics, 14 Jul. 2019, English, Oral presentation
  [International presentation]
• Volcanic gas measurements using UAVs
  Hashimoto T; Terada A; Mori T; Tanaka R
  Japan Geoscience Union, 26 May 2019, Japanese, Oral presentation
  [Domestic Conference]
• On the characterisics of ground deformation and demagnetization in inter-eruptive periods
  Hashimoto T; Utsugi M; Ohkura T; Kanda W; Terada A; Miura S; Iguchi M
  Japan Geoscience Union, 21 May 2018, Japanese, Oral presentation
  [Domestic Conference]
• Importance of multi-parameter monitoring during non-eruptive stage (an example from Mt. Tarume)
  Hashimoto T; Matsumoto M; Aoyama H; Koyama H; Morii A; Mishima W; Ogino T; Takahashi R; Okazaki N
  The Volcanological Society of Japan, 23 Sep. 2017, Japanese, Oral presentation
  [Domestic Conference]
• Long-term Correlation between Geomagnetic Filed Changes, Ground Deformation and Gas Composition at Mt. Tarumae Volcano, Northern Japan
  Hashimoto, T; Matsumoto, M; Okamoto, R; Koyama, H; Morii, A; Mishima, W; Ogino, T; Takahashi, R; Okazaki, N
  International Association of Volcanology and Chemistry of Earth's Interior, Aug. 2017, English, Oral presentation
  [International presentation]
• Volcano-magnetic field changes coincident with ground deformation
  Hashimoto T; Tanaka R
  The Volcanological Society of Japan, Oct. 2016, Japanese, Poster presentation
  [Domestic Conference]
• Detection of Aeromagnetic Field Changes Using an Unmanned Autonomous Helicopter: Repeated Experiments at Tarumae Volcano (Japan)
  Hashimoto T; Koyama T; Yanagisawa T; Yoshimoto M; Ohminato T; Kaneko T
  American Geophysical Union, Dec. 2015, English, Poster presentation
  [International presentation]
• Image processing for plume reduction
  Hashimoto T; Terada A; Tanaka R
  The Volcanological Society of Japan, Sep. 2015, Japanese, Oral presentation
  [Domestic Conference]
• Geomagnetic variations during inter-eruptive at volcanoes with an epithermal system
  Hashimoto T; Kanda W; Utsugi M; Ichiki M; Koyama T
  The Volcanological Society of Japan, Sep. 2015, Japanese, Poster presentation
  [Domestic Conference]
• Long-term volcano-magnetic effects associated with phreatic eruptions
  Hashimoto, T; Kanda, W; Utsugi, M; Ichiki, M
  International Union of Geodesy and Geophysics, General Assembly, 28 Jun. 2015, English, Oral presentation
  [International presentation]
• Re-examination of the geomagnetic changes in the early stage of the Usu 2000 eruption
  Hashimoto T; Mishima W
  The Volcanological Society of Japan, Nov. 2014, Japanese, Oral presentation
  [Domestic Conference]
• Geomagnetic Changes over Tarumae Volcano (Japan) Through Repeated Surveys Using an Unmanned Helicopter
  Hashimoto T; Koyama T; Yanagisawa T; Yoshimoto M; Kaneko T; Ohminato T; Suzuki E
  Asia Oceania Geosciences Society, Jul. 2014, English, Oral presentation
  [International presentation]
• A low-cost SO2 imager with the use of digital cameras of consumer use
  Hashimoto T; Terada A; Ejiri M; Nakamura T; Makoto Abo M
  International Association of Volcanology and Chemistry of Earth's Interior, Jul. 2013, English, Poster presentation
  [International presentation]
• Airborne surveillance using an unmanned autonomous helicopter at Tarumae volcano
  Hashimoto T; Ohminato T; Kaneko T; Yoshimoto M; Yanagisawa T; Suzuki E; Koyama T; Matsumoto M
  Japan Geoscience Union, 22 May 2013, Japanese, Oral presentation
  [Domestic Conference]
• Geomagnetic secular changes in eastern Hokkaido
  Hashimoto T; Mogi T; Nishimura M; Arita S; Shimizu J; I T; Minamoto Y; Nagamachi S
  Japan Geoscience Union, 24 May 2012, Japanese, Oral presentation
  [Domestic Conference]
• Aeromagnetic survey using an unmanned autonomous helicopter over Tarumae volcano
  Hashimoto T; Koyama T; Kaneko T; Ohminato T; Yoshimoto M; Suzuki E; Yanagisawa T
  Japan Geoscience Union, 23 May 2012, Japanese, Oral presentation
  [Domestic Conference]
• Secular changes in total magnetic field in the eastern Hokkaido;evaluation of large-scale variation by using IGRF-
  Hashimoto T; Mogi T
  Society of Geomagnetism and Earth, Planetary and Space Sciences, 05 Nov. 2011, Japanese, Oral presentation
  [Domestic Conference]
• 民生デジタルカメラを利用した簡易SO2カメラの製作
  橋本武志; 八神 樹; 寺田暁彦; 江尻 省; 中村卓司; 阿保 真; 吉川 慎
  日本火山学会, Oct. 2011, Japanese, Poster presentation
  [Domestic Conference]
• Cooling processes following eruptions at Usu volcano, as infrred from aeromagnetic repeat surveys
  Hashimoto T; Nakatsuka T; Okuma S; Utsugi M; Koyama T; Kanda W
  The Volcanological Society of Japan, Oct. 2011, Japanese, Oral presentation
  [Domestic Conference]
• Geomagnetic changes over Usu Volcano detected from aeromagnetic repeat surveys
  Hashimoto T; Utsugi M; Nakatsuka T; Okuma S; Koyama T; Kanda W; Suzuki A; Joint Group for; Usu Volcano Airborne Magnetic Survey
  Japan Geoscience Union, 23 May 2011, Japanese, Poster presentation
  [Domestic Conference]
• Heat accumulation beneath Tokachidake volcano as inferred from total magnetic field change (2)
  Hashimoto, T; Takahashi Y; Morii A; Shimizu J; I T; Okazaki N; Miyamura J; Joint EM Observation Team for; Tokachidake Volcano
  Society of Geomagnetism and Earth, Planetary and Space Sciences, Oct. 2010, Japanese, Oral presentation
  [Domestic Conference]
• Magnetic changes in the summit area of Usu volcano
  Hashimoto T; Suzuki A; Matsumoto M
  The Volcanological Society of Japan, Oct. 2010, Japanese, Oral presentation
  [Domestic Conference]
• Aeromagnetic survey over Usu volcano -plannning and feasibility-
  Hashimoto T; Utsugi M; Okuma S; Nakatsuka T
  Japan Geoscience Union, May 2010, Japanese, Oral presentation
  [Domestic Conference]
• Heat accumulation beneath Tokachidake volcano as inferred from total magnetic field change (2008-2009)
  Hashimoto T; Nishimura M; Yamamoto T; Arita S; Shigeno N; Ogiso M; Okazaki N; Mogi T
  The Volcanological Society of Japan, Oct. 2009, Japanese
  [Domestic Conference]
• Heat accumulation beneath Tokachidake volcano as inferred from total magnetic field change (2008-2009)
  Hashimoto T; Nishimura M; Yamamoto T; Arita S; Shigeno N; Ogiso M; Okazaki N; Mogi T
  Society of Geomagnetism and Earth, Planetary and Space Sciences, 27 Sep. 2009, Japanese, Oral presentation
  [Domestic Conference]
• On the inner structure and formation process of Komezuka scoria cone, Aso volcano
  Hashimoto T; Utsugi M; Komori S
  Japan Geoscience Union, May 2009, Japanese, Oral presentation
  [Domestic Conference]
• Electric and magnetic changes associated with volcanic processes
  Hashimoto T
  ASIAN INTERNATIONAL SYMPOSIUM ON MODELING OF VOLCANIC ERUPTION FOR VOLCANIC HAZARD ASSESSMENT, Dec. 2008, English, Oral presentation
  [International presentation]
• Resistivity structure across the intrusive zone of the 2000 eruption at Usu volcano
  Hashimoto, T; Y. Ogawa; S. Takakura; Y. Yamaya; H. Ichihara; T. Mogi
  The 19th International Workshop on EM Induction of the Earth, Oct. 2008, English
  [International presentation]
• Resistivity structure around the intrusion of the 2000 eruption at Usu volcano
  Hashimoto T; Ogawa Y; Takakura S; Yamaya Y; Ichihara H; Mogi T
  Japan Geoscience Union, 26 May 2008, Japanese, Oral presentation
  [Domestic Conference]
• Year-to-year Change in Self-potential on Unzen Volcano
  Hashimoto, T; Year-to-year Change in Self-potential on; Unzen Volcano
  Cities on Volcano 5, Nov. 2007, English, Poster presentation
  [International presentation]
• Continuous Geomagnetic Changes in Usu Volcano
  Hashimoto T; Suzuki A; Mogi T; Yamaya Y
  Society of Geomagnetism and Earth, Planetary and Space Sciences, Sep. 2007, Japanese, Oral presentation
  [Domestic Conference]
• Imaging of the electrical and thermal structure of a shallow magmatic intrusion associated with the 2000 eruption of Usu Volcano
  Hashimoto, T; Y. Ogawa; S. Takakura; H. Inoue; Y. Yamaya; M. Utsugi; T. Koike; H. Hasegawa; H. Ichihara; H. Satoh; T. Mogi
  International Union of Geodesy and Geophysics, Jul. 2007, English
  [International presentation]
• Geomagnetic changes in the active area of the 2000 eruption of Usu Volcano
  Hashimoto T; Suzuki A; Maekawa T; Mogi T; Yamaya Y
  Japan Geoscience Union, May 2007, Japanese, Poster presentation
  [Domestic Conference]
• Water and heat budget of Yudamari crater lake, Nakadake, Aso (revisited)
  Hashimoto, T; S. Ikebe
  The Volcanological Society of Japan, 23 Oct. 2006, Japanese, Oral presentation
  Aso, Kumamoto, [Domestic Conference]

  
  Preprint
• Resistivity survey of Asama Volcano by magnetotellurics, an analysis for the NS line, western summit area
  Takeshi Hashimoto; Research group for; Asama Volcano; EM field experiment
  Japan Geoscience Union, 14 May 2006, Japanese, Poster presentation
  Makuhari, Chiba, [Domestic Conference]

  
  Download
• 平成17年度浅間山電磁気構造探査の概要
  橋本武志; 浅間山電磁気構造探査グループ
  浅間山構造探査報告会, 03 Mar. 2006, Japanese
  東京, [Domestic Conference]
• Helicopter-borne magnetic survey over White Island -Is volcanomagnetic effect detectable by repeated survey?-
  Hashimoto, T; Y. Tanaka; M. Utsugi; A. W. Hurst; R. Yoshimura; W. Kanda; T. Matsushima; B. J. Scott; D. J. Woodward; T. Ohkura; T. Kagiyama; T. Ogawa
  International Symposium on Airborne Geophysics 2006, 10 Jan. 2006, Tsukuba, Ibaraki, English, Oral presentation
  Tsukuba, Ibaraki, [International presentation]
• 永年変動によるみかけの全磁力変化－火山地磁気効果の評価－
  橋本武志
  Conductivity Anomaly研究会, 20 Dec. 2005, Japanese, Oral presentation
  東京, [Domestic Conference]
• Ｈ１７年度浅間山電磁気構造探査序報
  橋本武志; 鈴木敦生; 茂木 透; 山谷祐介; 三品正明; 中塚 正; 小山崇夫; 小山悦郎; 小川康雄; 相沢広記; 氏原直人; 松尾元広; 平林順一; 野上健治; 田中良和; 鍵山恒臣; 宇津木充; 神田 径; 宇都智史; 大久保綾子
  Conductivity Anomaly 研究会, 20 Dec. 2005, Japanese, Oral presentation
  東京, [Domestic Conference]
• 平成１７年度浅間山電磁気構造探査序報
  橋本武志; 鈴木敦生; 茂木 透; 山谷祐介; 三品正明; 中塚 正; 小山崇夫; 小山悦郎; 小川康雄; 相沢広記; 氏原直人; 松尾元広; 平林順一; 野上健治; 田中良和; 鍵山恒臣; 宇津木充; 神田 径; 宇都智史; 大久保綾子
  東京大学地震研究所第８３３回談話会, 25 Nov. 2005, Japanese, Oral presentation
  東京, [Domestic Conference]
• Geomagnetic change due to doming -Re-examination of total field change in the Usu 2000 eruption revisited-
  Hashimoto, T
  Seciety of Geomagnetism and Earth, Planetary and Space Sciences, 28 Sep. 2005, Japanese
  Kyoto, [Domestic Conference]
• ロングバレー・カルデラ －最近数十年の活動と地磁気観測の目標－
  橋本武志
  シンポジウム「カルデラの構造と活動そして現在－Out of rangeへの挑戦」, 29 Jul. 2005, Japanese, Oral presentation
  熊本, [Domestic Conference]
• A helicopter-borne geomagnetic survey on White Island, New Zealand (FY2004)
  Hashimoto, T; Y. Tanaka; M. Utsugi; A. W. Hurst; R. Yoshimura; W. Kanda; T. Matsushima; B. J. Scott; D. J. Woodward; T. Ohkura; T. Kagiyama; T. Ogawa
  地球惑星科学関連学会合同大会, 22 May 2005, Japanese, Poster presentation
  Makuhari, Chiba, Japan, [Domestic Conference]

  
  Published
• 自然電位の定量的評価に向けた流動電位実験
  橋本武志; Annamaria Vicari
  特定領域研究「火山爆発のダイナミクス」シンポジウム, 01 Mar. 2004, Japanese, Oral presentation
  東京, [Domestic Conference]
• On the annual variations in geomagnetic differences observed in Long Valley Caldera, California
  Hashimoto, T; M. J; S. Johnston; Y. Tanaka; Y. Sasai; M. Utsugi; S. Sakanaka
  Inernational Union of Geodesy and Geophysics, 30 Jun. 2003, English, Oral presentation
  Sapporo, Japan, [International presentation]
• Heat discharge, water level and geomagnetic changes of the crater lake, Aso Volcano, Japan
  Hashimoto, T; S. Ikebe; H. Ono; Y. Tanaka
  Western Pacific Geophysics Meeting, 09 Jul. 2002, English
  Wellington, New Zealand, [International presentation]

  
  Download
• Developing Hydrothermal System and Self-potential Changes Associated with Magma Intrusion
  Hashimoto, T; Y. Tanaka; T. Kagiyama
  Japan Earth and Planetary Science joint meeting, May 2002, Japanese, Oral presentation
  Tokyo, [Domestic Conference]

  
  Download
• Heat Discharging Process and Geomagnetic changes of Iwoyama, Kuju Volcano
  Hashimoto, T; M. Utsugi; S. Sakanaka; Y. Tanaka
  Annual meeting of Disaster Prevention Research Institute, Kyoto University, Feb. 2002, Japanese, Oral presentation
  Kyoto, [Domestic Conference]

  
  Download
• Self-potential changes on Unzen Volcano 1991-2001
  Hashimoto, T; Y. Tanaka; T. Kagiyama
  Unzen Workshop 2002, Jan. 2002, English, Poster presentation
  Shimabara, [International presentation]

  
  Download
• Heat discharge, water level geomagnetic variation observed at Aso Nakadake Volcano
  Hashimoto, T; Y. Tanaka; M. Utsugi; S. Ikebe
  Seciety of Geomagnetism and Earth, Planetary and Space Sciences, Nov. 2001, Japanese
  Fukuoka, [Domestic Conference]

  
  Download
• Changes of water level and heat discharge observed at the crater lake of Aso Nakadake
  Hashimoto, T; S. Ikebe; Y. Tanaka; H. Ono; M. Nakaboh
  Volcanological Society of Japan, Oct. 2001, Japanese, Oral presentation
  Kagoshima, [Domestic Conference]

  
  Download

• 構造探査学特論, 2024年, 修士課程, 理学院
• 自然史科学特別講義Ⅰ, 2024年, 修士課程, 理学院
• 自然史科学特別講義Ⅱ, 2024年, 修士課程, 理学院
• 構造探査学特論, 2024年, 修士課程, 理学院
• 地球計測実習, 2024年, 学士課程, 理学部
• 地球惑星電磁気学, 2024年, 学士課程, 理学部
• 地球惑星科学のための電磁気学, 2024年, 学士課程, 理学部

• 2020 - Present
  International Association of Volcanology and Chemistry of the Earth's Interior
• JAPAN GEOSCIENCE UNION
• The Volcanological Scociety of Japan
• Society of Geomagnetism and Earth, Planetary and Space Sciences

• Comprehensive study on the 2018 Hokkaido Eastern Iburi Earthquake and its disaster
  Grants-in-Aid for Scientific Research
  04 Oct. 2018 - 31 Mar. 2019
  Takahashi Hiroaki
  Comprehensive investigation on the 2018 Hokkaido Eastern Iburi earthquake and its disaster was conducted. Mainshock rupture initiated at deepest part and major slip was occurred in 20-30km deep. Multiple simultaneous landslides in Atsuma town was induced by combination of strong ground shaking and weak sliding layer between pyroclastic fall deposit layers. Halloysite cray minerals was discovered in all sliding layers. Simulation suggested landslides might attack residential houses within 6 seconds. Observed peak ground motions in nearby area were larger than common distance attenuation model. Severe wooden house damage in Mukawa town was due to amplified seismic waves due to site effects. Sounding and boring investigation revealed filled low-density volcanic ash and higher groundwater level in liquefaction area. Electricity blackout caused severe damage in social and economic activities of Hokkaido. These scientific outcomes were explained to residents at public briefing session.
  Japan Society for the Promotion of Science, Grant-in-Aid for Special Purposes, Hokkaido University, 18K19952
• Comprehensive study of the Eruption of Ontake volcano in 2014
  Grants-in-Aid for Scientific Research
  10 Oct. 2014 - 31 Mar. 2016
  Yamaoka Koshun; NAKADA Setsuya; MIYAKE Yasuyuki; SUZUKI Takehiko; YAMANAKA Yoshiko; OHKURA Takahiro; MATSUSHIMA Takeshi; NAKAMICHI Haruhisa; OZAWA Taku; TAKEO Minoru; HASHIMOTO Takeshi; MORI Toshiya; TERADA Akihiko; NOGAMI Kenji; SANO Yuji; TADOKORO Keiichi; TAKAGI Akimitsu
  In the study of the 2014 eruption of Ontake Volcano we obtained the following results. 1) Regarding the studies on surface change and eruption material, we obtained the aerial and satellite image and laser profile data to compare the topography before and after the eruption. We also clarified the detailed eruption process by the geological survey of the summit area. 2) We clarify the process leading to the phreatic eruption and afterwards by analyzing the existing data set on earthquake and crustal deformation together with the newly obtained data by deploying seismometers. 3) We confirmed that the post-process of the 2014 eruption follows that of the 1979 one by analyzing the volcanic gas that sampled using an unmanned aerial vehicle. 4) In the study of disaster information dissemination, we clarify the preparedness for the volcano disasters in the community around Ontake Volcano.
  Japan Society for the Promotion of Science, Grant-in-Aid for Special Purposes, Nagoya University, 26900002
• Application of spectroscopy in remote sensing of volcanic gases
  Grants-in-Aid for Scientific Research
  01 Apr. 2012 - 31 Mar. 2015
  HASHIMOTO Takeshi; TERADA Akihiko; MORI Toshiya; NAKAMURA Takuji; EJIRI Mitsumu; ABO Makoto
  It has generally been believed that remote-sensing of water (vapor and mist) in volcanic plume is practically very difficult. This research aimed to visualize water content in volcanic plumes as an infrared image via absorption of background solar radiation through the water. Unfortunately this method was proven to be unsuccessful at least in the humid atmospheric conditions in our nation. We, however, improved our low-cost imager of sulfur dioxide gas in volcanic plumes using ultraviolet wavebands. In addition, we made it possible to remotely detect water vapor and water mist separately by using our portable Raman LIDAR system.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 24540446
• Research on the true picture of magma supply system, which is supposed to be beneath the sea area, by means of the investigation of underground structure
  Grants-in-Aid for Scientific Research
  2009 - 2012
  KANDA Wataru; HASHIMOTO Takeshi; YAKIWARA Hiroshi; KASAYA Takafumi; OGAWA Yasuo; KOYAMA Takao; UTSUGI Mitsuru; ICHIHARA Hiroshi
  In order to clarify the corresponding electrical resistivity structure to the assumed magma reservoir and to the supply paths to Sakurajima volcano and to the submarine volcano, we have conducted the magnetotelluric (MT) measurement mainly along two traverse lines in the direction of WNW-ESE crossing the Aira caldera since 2009. The MT data at 44 sites in total, including 16 seafloor sites, were obtained for the last four years. As a result of 2-D and3-D inversions, a high conductive region extending from the lower crust along the Kagoshima graben was found from the central part of the caldera to the eastern part. This conductor is possibly the structure relevant to the magma supply system.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Tokyo Institute of Technology, 21310116
• General study on the eruption at Shinmoedake volcano, Kirishima, in 2011
  Grants-in-Aid for Scientific Research
  2010 - 2011
  NAKADA Setsuya
  A magmatic eruption event took place at Shinmoedake (Kirishima) Volcano in January 2011, leaving about 300 years of hiatus. Three subplinian explosions occurred on 26 and 27 January, which were followed by 4-day accumulation of lava at the summit crater. Vulcanican explosions were repeated from February to April, and a series of eruptions ended with phreatic explosions which occurred in June and September 2011. This eruption event was preceded by both phreatic explosions in 2008 and 2010 and elevated seismic activity in the regions surrounding Kirishima. GPS observation indicated that significant swelling of the magma chamber which located about 6 km NW of the Shinmoedake crater had continued since the end of 2009. Deflation of the magma chamber accompanied clearly subplinian explosions and the lava accumulation in the crater. The strain-meter observation showed small increases in pressure several tens of minutes prior to the subplinian explosions. Seismic array-observation during a series of vulcanian explosions showed that volcanic tremors occurred beneath the summit crater and between it and the magma chamber, supporting magma's migration from the magma chamber to the crater. The latter was confirmed by the absolute gravity measurement at the place just above the magma chamber. Inflation of the summit area, ncrease in the shallow earthquakes and decrease in the volcanic gas emitted from the crater were observed prior to the vulcanian explosions, strongly implying sealing of the conduit top preceding the explosions. It is considered that magma mixing occurred just before the eruption event because the products of the earliest stage consisted of two magmas with different compositions. The total volume of magma erupted in this event is estimated about 25 million m3, which is about 1/3 volume of the eruption 300 years ago.
  During this study, we tried two times to make the eruption scenario in which sequences of eruptions are indicated, based on records of eruptions of this volcano 300 years ago and of analogous volcanoes in and outside Japan. No significant mudflows occurred in this eruption event. It is considered that the reason is that the eruption products were mainly of pumice which has high permeability of rain water. Inflation of magma chamber resumed soon after the eruptions in January 2011 and continued by the end of 2011, reaching the same level before the eruption event. It almost stopped in the beginning of 2012, suggesting a halt of the magma supply from depth.
  Japan Society for the Promotion of Science, The University of Tokyo, 22900001
• Sophistication of remote sensing in volcanic gas measurements
  Grants-in-Aid for Scientific Research
  2009 - 2011
  HASHIMOTO Takeshi; NAKAMURA Takuji; TERADA Akihiko; ABO MAKOTO
  This study aimed an innovative progress in the remote sensing of volcanic gases by introducing some spectroscopic techniques which have been widely used in the research field of atmospheric science. Followings are the major achievements of this study. (1) Sophistication of the Raman LIDAR system for the water-vapor measurement. This study appended a liquid water channel to the previous instrument, which made separate detection of water vapor and mist in a volcanic plume possible. (2) Development of the high spectrum-resolution LIDAR for the measurement of a temperature profile in a volcanic plume. (3) Fabrication of a low-cost version of the SO2 camera which visualizes the concentration of sulfur dioxide in a volcanic plume.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 21340122
• 火山噴煙のリモートセンシングに関する新手法の開発
  科学研究費助成事業
  2006 - 2008
  橋本 武志; 寺田 暁彦; 中村 卓司; 高橋 幸弘
  20年度は, 本研究課題の最終段階として, 2008年10月に再び阿蘇中岳火口でラマンライダーとスペクトルカメラによる噴煙水蒸気観測を行った. 今回は, 前回までの阿蘇での観測と登別大湯沼での観測をふまえ, 火口湖から蒸発する水蒸気と, 噴気口からまとまって放出されている水蒸気とを区別できるように工夫した. 具体的には, ライダーのビームを水平方向にスキャンして, 水平面内での水蒸気分布を求めた, 別途暗視カメラで上昇速度を測定し, 水蒸気フラックスを算出することができた. これにより, 湖面からの蒸発と噴気水蒸気とを区別することができ, 本課題の当初の目標のひとつであった湖面蒸発率の正確な推定を達成することができた.
  スペクトルカメラについては, 新規の試みであったこともあり, 測定手法の模索に終始したが, 本研究課題によって一定の見通しが得られた. 800nm近辺の赤外吸収帯を用いることにより, 大気水蒸気による吸収の影響を抑えながら, 火山起源の水蒸気による赤外吸収を捉え得ることを実証できた, ただし, 背景光(太陽光)と火山噴煙との位置関係や気象条件による制約が大きいことが問題点として残っている. また, 野外での即時データ処理方法や機器の操作性などの面で, さらに改良すべき点もある.
  2008年9月には, 代表者と連携研究者が集まり, 3年間の到達点と今後のステップに向けた改良点について議論した. その結果, 来年度以降もライダーおよびスペクトルカメラを用いた火山ガス研究を発展的に継続することを確認し, さらなる研究目標に必要な装置のスペックに関する青写真を作った.
  日本学術振興会, 萌芽研究, 北海道大学, 18654075
• Japan-Russia-USA joint research of volcanic activity, seismic activity and crustal deformation of Kuril arc
  Grants-in-Aid for Scientific Research
  2005 - 2008
  NAKAGAWA Mitsuhiro; KASAHARA Minoru; HASGIMOTO Takeshi; TAKAHASHI Hiroaki; NISHIMURA Yuichi; YOSHIMOTO Mitsuhiro; KAZAHAYA Kohei; ISHIZUKA Yoshihiro; KANEKO Takayuki
  日露米の3ケ国により南千島ウルップ島から北千島パラムシル島で、ビザ無し専門家交流により日露で色丹・国後・択捉島で、火山学的および古津波調査を実施した。その結果、千島列島の過去1万年間の火山噴火履歴と、主要な噴火の噴火様式および特に南千島での津波の発生間隔を検討した。特に火山活動では、9500～6500 年前および4000～1000年前にカムチャッカ～北海道まで大規模な噴火が頻発したこと、またマグマ組成の広域変化が基盤構造の差異と調和的であることを始めて指摘できた。
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Hokkaido University, 17253002
• Monitoring of the volcanic fluid system and elucidation of the deep-magma ascent mechanism at Aso volcano
  Grants-in-Aid for Scientific Research
  2003 - 2006
  KAWAKATSU Hitoshi; SUDO Yasuaki; OKURA Takahiro; KANESHIMA Satoshi; YAMAMOTO Mare; HASHIMOTO Takeshi
  In order to monitor the volcanic fluid system and to elucidate the mechanism of magma ascent before eruptions, we deployed broadband seismometer and GPS networks in Aso volcano. We also conducted a series of dense array observations to monitor shallow fluid flow activities. As the result, (l) we were successful to observe extremely fast fluid movements in the shallow part of the volcano that appear to indicate a well developed shallow conduit system, (2) we have presented a model that explains the activities of long-period (15s) and short-period (1s) tremors as a result of the activities of a single conduit system of hydrothermal fluid flows. We have also developed an efficient method to compute the dynamic response of a fluid-filled crack that is flexible to many applications which may be encountered in volcano seismology.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), The University of Tokyo, 15204040
• Elucidation of contributing factors affecting the ζ-potential of volcanic rocks
  Grants-in-Aid for Scientific Research
  2004 - 2005
  HASHIMOTO Takeshi
  ζ-potential of several rock samples from various volcanoes was measured by using streaming potential method. Effects of surface conductivity was also taken into accounted for calculating ζ-potential. This procedure is necessary because surface current on the sample cell is not negligible when compared to the current through pore. Pressure gauge has been implemented to the instrumentation system in the second year.
  In general, ζ-potential of rock samples show strong dependency on pH of the circulating fluid. Four of the seven samples showed positive ζ-potential under the natural condition without pH control. Such rock samples with positive ζ-potential have already been reported by Hase et al. (2004) which measured the ζ-potential of samples from Aso Volcano. The present study has revealed that such 'anomalous' rocks are not very rare.
  The author investigated the relationship between major elements and ζ-potential of the rock samples in order to elucidate the contributing factors affecting the polarity of the ζ-potential. However, the correlation between each element and ζ-potential does not seem to be very clear. It was suggested that there should be some hidden factor other than the composition of rock sample itself. Further investigation including mineral composition and dissolved component in the fluid is necessary.
  Another contribution of the present research is the field measurement of electrical resistivity of Tarumae Volcano, Hokkaido. Our magnetotelluric measurement has revealed that there is a very conductive body just beneath the summit crater of the volcano. This result supports the hydrothermal circulation model that is inferred from self-potential anomaly on the volcano.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 16540375
• Detection of volcano-magnetic changes by aero-magnetic survey
  Grants-in-Aid for Scientific Research
  2003 - 2005
  TANAKA Yoshikazu; HASHIMOTO Takeshi; UTSUGI Mitsuru; KANDA Wataru; KAGIYAMA Tsuneomi; OKURA Takahiro
  Four persons made a voyage to White Island of the New Zealand, the proton magnetometer was installed in two points, and ground continuation magnetic field observation was started and also SP measurement was performed in 2003 fiscal year.
  While five persons made a voyage in the 2004 fiscal year and performing recovery of continuation magnetic field data and ground repetition magnetic field observation, the aero-magnetic survey of the airraid altitudes 50m and 100m was carried out with helicopter. Seven persons made a voyage in the Heisei 17 fiscal year, and the repetition magnetic survey in the ground and the air was carried out. Unfortunately, volcanic activity of the White Island was calm and remarkable magnetic change was not detected. However, the observation technical problem about an air magnetism survey was mostly solved through this research.
  Namely, the positioning of the flight sensor was achieved with installation of highly precise GPS receiver in the ground and a bird. It asks with an error 1m or less by carrying out differential analysis. It is necessary to detach 40m to avoid the influence of magnetization of a helicopter to the body, and a bird hanging system is excellent in it. The form and cylinder wings of a bird for obtaining a stable flight have been determined. The highly precise cesium magnetometer has owned at the university. The system which displays a GPS position on a PC screen in realtime, and is used for route guidance has been developed.
  It is also one of the results that it was able to be shown that a flight experiment can be repeated in the volcano in Aso, Kuju, Sakurajima, Bandai, and Asama ignited by this research, and an air magnetic survey can carry out comparatively easily also by the researcher of a university.
  The subject which especially catches a volcanic magnetic field change by the air magnetic survey which was the big target of this research has been attained by having obtained the result which detects ground observation and a conformable volcanic magnetic field change of 50nT from the analysis of the air magnetism survey data in 1996 in the Kuju volcano, and 2004.
  These research results presented in the study group of the ISAG2006 air physics inquiry international symposium held in Tsukuba in January, 2006.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), KYOTO UNIVERSITY, 15403007
• 火山爆発の理解に向けた自然電位の基礎実験
  科学研究費助成事業
  2003 - 2004
  橋本 武志
  昨年度採取した火山岩の試料を用いて,流動電位法によるゼータ電位測定を行った.これまでに測定の終わったものは,十勝岳・利尻島・テネリフェ島から採取した7サンプルである.岩石サンプルは0.5mm直径に粉砕し,測定セルに装填した.セルに流動水を通過させたときに両端に生じる電位差を測定することにより,ゼータ電位が測定される.
  一般に,岩石のゼータ電位は流動水のpHに対して依存性を示す.今回の測定では,これまでHase(2004)等が示した実験結果と同じく,pH値が大きくなるにつれてゼータ電位が小さくなる傾向が示された.7サンプルのうち,4サンプルが,pH未調整状態の測定で正のゼータ電位を示した.正のゼータ電位を示すサンプルは,Hase(2004)により阿蘇火山でも見つかっているが,今回の測定は,その他の火山でも正のゼータ電位を示す岩石は希ではないことを示唆している.これまで,岩石-水の系では,ゼータ電位は負の値をとるという認識が一般的であったが,それは必ずしも正しくないことが本研究で示された.
  ゼータ電位の正負を決定している要因について調べるため,岩石の元素組成とゼータ電位の関係を吟味した.その結果は必ずしも明瞭ではなく,主要構成元素の組成だけでゼータ電位が決定されている訳ではないことが示唆された.今後,造岩鉱物組成まで考慮した検討が必要である.
  本研究課題でこれまでに得られた成果は,2005年1月に神戸で開かれた本特定領域研究主催の国際シンポジウム「火山爆発研究の基本戦略」で発表したほか,2005年3月に東京で開かれた本特定領域研究の成果報告シンポジウムで発表した.
  日本学術振興会, 特定領域研究, 北海道大学, 15038211
• 自然電位および土壌ガスの確率的トモグラフィによる火山の浅部熱水系の解明
  科学研究費助成事業
  2001 - 2002
  橋本 武志
  本研究課題では,阿蘇火山をテストフィールドとして,土壌ガス(二酸化炭素)フラックスの分布と自然電位分布の関係を明らかにすることが主たる目的であった.
  1.このため,面的測定が容易なチャンバー方式のガスフラックス計を備品として購入した.
  2.阿蘇カルデラの周縁部および中央火口丘の一部で,これまで不足していた自然電位分布の測定を補充した.中央火口丘では中岳火口を中心とする高電位異常の他に,湯ノ谷温泉・地獄温泉の両地域では局所的な高電位異常が存在することが明らかになった.
  3.カルデラ内で二酸化炭素フラックス計による測定を行ったところ,上記温泉地域では,顕著に二酸化炭素フラックスが高いことが明らかになった.最もフラックスの高かったのは湯ノ谷温泉の噴気口近傍で,800g/m2/day程度の値が計測された.これらのことから,自然電位異常(高電位部分)は熱水の上昇に伴う流動電位である可能性が高い.ただし,高フラックスの領域はそれほど広くなく,むしろ噴気口の周辺に限られていた.阿蘇火山は,近年いくつかの火山で報告されているように山体の広い範囲からじわじわと二酸化炭素が放出されるタイプではないようである.
  4.3次元の電場計算コードを開発した.これにより,観測された自然電位マップから等価電流源の強さと位置を推定したところ,中岳火口直下の深さ約1〜2km程度の位置に10A程度の電流源が推定された.
  5.中央火口丘のいくつかの地点から岩石をサンプリングし,ζ電位の測定を行った.その結果,高岳・杵島岳周辺の岩石はζ電位が通常とは逆符号の正の値をとることがわかった.この結果は,今後自然電位モデリングを進める上で極めて重要な情報となる.
  日本学術振興会, 若手研究(B), 京都大学, 13740268
• Crustal Electric Structure in the East-china Sea Observed by Submarine Cable
  Grants-in-Aid for Scientific Research
  1999 - 2001
  TANAKA Yoshikazu; SHIMOIZUMI Masaaki; HASHIMOTO Takeshi
  Summary of research results The induction vector observed on land in Kyusyu pointed to the southwest. Induction effect of Pacific Ocean could not explain this effect, and existence of high conductive layer in the west part sea area of Kyusyu was pointed out. However little electrical data existed in the west sea area.
  We notice retired metallic submarine cable laid by NTT, and the electric potential were measured following 5 areas. The data stored in personal computer in each second through 6.5 digits electrometer (Yokogawa 7561 or HP34970A+HP34902A) with the resolution 100uV or 10uV. The computer clock was corrected by GPS. The electrical resistivity beneath the cable was obtained by MT analysis using magnetic data observed at Kanoya.
  1) Okimawa area : The coherency to magnetic changes of NS component is very high. R is several 100 to 1000 ohm-m, and uniform in laterally. The results of 1000 ohm-m until 30km support Shimakawa's model, but not show low resistive in deeper part.
  2) Kagishima area : The coherency is high to magnetic NS and EW component. R is obtained several 100 to 1000 ohm-m, and not support existence of low resistive zone in deeper part.
  3) Koshiki area : R of Kushikino - Naka Koshiki is 10 ohm-m and Naka Koshiki - Satomichi is several 10 ohm-m. They are very low compared with Okinawa and Southern Kagoshima, and not uniform to NS and EW direction.
  4) Nagasaki area : High conductive layer is detected in lower crust to upper mantle. The R are 0.3 ohm-m (<100m), 30 ohm-m(<30km), 300 ohm-m (<80km), 3 ohm-m (<80km).
  5) Iki area : The results show existence of high conductive layer in lower crust to upper mantle as same as West Nagasaki. The resistivity are 0.3 ohm-m (<1000m), 30 ohm-m (>1km).
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), KYOTO UNIVERSITY, 11640416
• 地下浅部に貫入したマグマの冷却過程の解明
  科学研究費助成事業
  1999 - 2000
  橋本 武志
  雲仙岳山頂部では,1991年より本科研費代表者らを中心として自然電位のモニタリングが行われており,これまでに,溶岩ドーム出現に先立つ急激な電位の上昇や,その後の周辺部での電位低下が捉えられた.これらの現象は熱水対流系の発達過程を電位変化として捉えたものと解釈される.自然電位の長期にわたる変動を観察することは,1991年の噴火で地表付近にセットされた熱源(マグマ)によって熱水対流系がどのような発達過程を遂げるか(その規模や寿命)を推察する有力な手法である.本年度は昨年度に引き続き,山頂部での自然電位繰り返し測定を行った.その結果,以下のことが明らかになった.
  (1)噴火直後から見られた溶岩ドームを中心とする高電位異常は平成12年度現在も存在する.
  このことは,一旦発達した対流系(上昇流)が噴火後も基本的には存続していることを意味する.
  (2)ドームのごく近傍では,緩やかながら依然として電位の上昇が継続している.
  (3)一方,ドームの南西部(薊谷の北東部)では,昨年度に引き続き,1997頃から電位が低下傾向を示している.この領域は,噴火初期に急激な電位上昇が観察された場所であり,ドーム貫入によって形成された地下の熱水対流系が,周辺部から衰退を始めていることを示唆するものである.
  本研究で得られた成果は,2000年6月に東京で開かれたWestern Pacific Geophysics Meeting(合衆国地球物理学会主催)で発表した.
  また,観測された電位変化を定量的に考察するため,熱水対流と電位計算を結合させた計算機によるシミュレータを開発した.今後,このシミュレータを使って熱水系の発達過程を考察していく予定である.
  日本学術振興会, 奨励研究(A), 京都大学, 11740258
• Elucidation of the Pressure Source Beneath the Active Crater of Aso Volcano
  Grants-in-Aid for Scientific Research
  1997 - 2000
  KAWAKATSU Hitoshi; TSUTSUI Tomoki; KANESHIMA Satoshi; SUDO Yasuaki; OHMINATO Takao; HASHIMOTO Takeshi
  Seismic wavefields observed near active volcanoes contain plenty of information about volcanic activities in the frequency range between 0.01 Hz and 1.0 Hz, where, until recently, conventional geophysical monitoring of volcanoes had riot paid much attention except for a few rare cases. The physics operating in a volcano is extremely complex; in different frequency bands, different physical processes dominate the wavefield, which makes broadband seismic observations essential to unravel the physical processes of volcanic activity using seismic data.
  Deployment of a dense network of broadband seismometers in Aso revealed a hydrothermal reservoir 1 to 1.5 kilometers beneath the crater that is continually resonating with periods as long as 15s, even when there is no apparent surface activity at the crater. When phreatic eruptions are observed, broadband seismograms elucidate vividly the whole eruption process: gradual pressurization and long-period (about 20s) pulsations of the reservoir during the 100-200s before the initiation of the discharge, followed by gradual deflation of the reservoir concurrent with the discharging flow. The observed spatial variation of the signal amplitudes reveals that the source of 15s long period tremors (LPTs) consists of an isotropic expansion (contraction) and an inflation (deflation) of an inclined tensile crack with a strike almost parallel to the chain of craters. The extension of the buried crack plane meets the crater chain, including the active fumarole at the surface, suggesting that the crack has played an important role in transporting steam (gasses) and/or lava to the craters from below. This work also demonstrates a powerful usage of broadband seismometers as geodetic instruments to constrain subsurface structures at active volcanoes.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), University of Tokyo, 09304043
• Investigations of volcanic structure and intruded magma by means of the geoelectrical method - Usu, Miyake-jima and Hokkaidou Komagatake -
  Grants-in-Aid for Scientific Research
  1997 - 1999
  NISHIDA Yasunori; KAGIYAMA Tsuneomi; TANAKA Yoshikazu; SASAI Yoichi; OGAWA Yasuo; HASHIMOTO Takeshi
  Present study has aimed to elucidate the volcano-hydrological environment including the hydrothermal circulation system and to detect the intruded magma by using the geoelectrical methods. For these purposes, we made magnetotelluric observations and self-potential measurements on Usu (dacite magmatism). Miyake-jima (basaltic magmatism) and Hokkaido Komagatake (andesitic magmatism) volcanoes.
  1) The common feature of the resistivity structure is seen beneath the three volcanic edifices: The first layer (100m or so) is resistive (about 1000 ohm-m) due to the volcanic rocks and sediments. The second layer is composed of the conductive rocks (several to several tens of ohm-m), suggesting the existence of the ionized water. This layer covers the relatively resistive third layer (several hundreds of ohm-m). The third layer is assumed to be the pre-Tertiary rocks.
  2) Positive self-potential anomalies are commonly observed on summit craters (Usu, 400 mV; Miyake-jima, 800 mV; Hokkaido Komagatake, 600 mV). These anomalies can originate from the upwelling of hot groundwater warmed by the heat supplied from deep-seated magma. These findings of hydrothermal circulation are important to consider the magma cooling process.
  3) Magnetotelluric soundings on Usu revealed the relatively highly resistive body (400 ohm-m or so) beneath the summit crater. Considering the relation between the resistivity of dacite rock and temperature, and the fumarolic temperature of Usu (500〜600℃, this body is identified as the intruded magma at the time of the 1977-1978 eruptions.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), HOKKAIDO UNIVERSITY, 09440155
• 阿蘇火山の浅部熱活動に伴う地下水流動と熱放出過程の研究
  科学研究費助成事業
  1997 - 1998
  橋本 武志
  本研究では,阿蘇火山における地下浅部熱放出過程を,熱エネルギー収支の観点から理解することを念頭に複合的観測を実施した.以下にその経過と得られた知見をまとめる.
  まず,活動火口近傍の地磁気連続観測によって火口直下数百m程度の温度状態の監視を行った.これによれば1997年以来継続していた温度低下の傾向が1998年3月を境に温度上昇へと転じている.以下に述べるように自然電位や噴気活動に大きな変動が観測されていないことから,この時期に深部から何らかのエネルギー供給が行われた可能性がある.
  地磁気観測と並行して,火口の東南側に電極を配置して自然電位の連続観測を行った.観測当初は雷害により安定したデータが取得できなかったため,電源を太陽電池方式にするなどの処置を施した.この連続観測では研究期間中有意な変動は見られなかった.しかしながら,中央火口丘規模(5km×5km程度)のスケールで自然電位の空間分布を調査したところ,山頂部付近で明瞭な高電位を示すことが明らかになった.従って,阿蘇火山が比較的大規模な熱水対流系を擁していることは確かである.
  本研究では,阿蘇火山の噴気にプリュームライズ法を適用して放出熱エネルギー量を見積もる予定であったが,研究期間中の噴気活動は一貫して低調で,この方法の適用に不向きな条件であった.そのため,デジタルビデオカメラを用いた実験の代替地として九重火山を選定した.ビデオ画像をパソコンに取り込んで噴気を追跡し,プリュームライズ法を適用した.カメラを固定して撮影を行えば自動処理による放出工ネルギーのモニタリングも可能であることがわかった.また,この方法によるエネルギー量算出の妥当性を検証するために,別府温泉の噴気を利用してビトー管による直接測定との比較測定を行った.この結果,プリュームライズ法はファクター2程度の誤差で放出エネルギーを見積っていることが明らかとなった.
  日本学術振興会, 奨励研究(A), 京都大学, 09740353
• 火山・地熱地域における電磁気現象に関する研究
  1995
  Competitive research funding
• Self-potential and hydrothermal circulation in volcanic and geothermal areas Studies on subsurface structure of volcanoes using electromagnetic methods
  Competitive research funding