Researcher Database

FURUYA Masato
Faculty of Science Earth and Planetary Sciences Earth and Planetary Dynamics
Professor

Researcher Profile and Settings

Affiliation

  • Faculty of Science Earth and Planetary Sciences Earth and Planetary Dynamics

Job Title

    Professor

E-mail

  • furuya@sci.hokudai.ac.jp

URL

Research funding number

  • 60313045

ORCID ID

  • 0000-0002-5638-5048

Research Interests

  • Extreme weather   gravity   volcano   earthquake   InSAR   permafrost   ionosphere   glacier   Earth rotation   crustal deformation   SAR   Space geodesy   

Research Areas

  • Earth and planetary science / Space and upper atmospheric physics
  • Environmental science / Environmental dynamic analysis
  • Earth and planetary science / Solid earth and planetary physics
  • Social/Safety system science / Natural disaster science
  • Earth and planetary science / Meteorology/Physical oceanography/Hydrology

Academic & Professional Experience

  • 1997 - 1999     Researcher,Communications Research Laboratory

Education

  •        - 1997  The University of Tokyo  Graduate School, Division of Science
  •        - 1992  The University of Tokyo  Faculty of Science

Association Memberships

  • THE JAPANESE SOCIETY OF SNOW AND ICE   The geodetic society of Japan   The volcanological society of Japan   The seismological society of Japan   The meteorological society of Japan   American Geophysical Union   Japanese Geoscience Uniton   

Research Activities

Published Papers

  • Yuji Himematsu, Freysteinn Sigmundsson, Masato Furuya
    Journal of Geophysical Research, Solid Earth 124 2019/08 [Refereed][Not invited]
     Research paper (scientific journal) 
    Bárðarbunga is an active volcano beneath the Vatnajökull icecap in Iceland, where a subglacial dike intrusion occurred in 2014. This area has been studied with interferometric synthetic aperture radar, an important geodetic method that measures crustal deformation; however, ice/snow cover on volcanoes impedes the mapping of crustal deformation because of decorrelation problems. Previous geodetic observations have reported deformation signals at ice‐free regions of a major dike formed in 2014 in the Bárðarbunga volcanic system, but direct observations of the subglacial crustal deformation associated with the dike intrusion have been limited. We applied a pixel tracking approach to various satellite synthetic aperture radar (SAR) data over the northern part of the Vatnajokull icecap and the Holuhraun plain. The pixel tracking data revealed not only crustal deformation fields in the ice‐free region of the magma intrusion, which covers only about 20% of the entire length of dike, but also icecap surface movements over the subglacial part of the dike in the ablation area of the Vatnajökull icecap. Signals above the icecap, suggesting subsidence due to subglacial graben formation, are consistent with the dike propagation path inferred from seismicity during the episode. By subtracting the scaled pre‐diking signals from the co‐diking signals, we corrected for the steady‐state icecap flow signals to derive the subglacial crustal deformations. We showed that the inferred subglacial crustal deformation signals can significantly contribute to the improvement of dike opening/faulting distributions. Applying the pixel tracking to satellite images will enable mapping subglacial crustal deformation in the case of subglacial volcanic activity.
  • IIO Kento, FURUYA Masato
    Progress in Earth and Planetary Science 5 61  2018/10 [Refereed][Not invited]
     Research paper (scientific journal)
  • USMAN Muhammad, FURUYA Masato
    Journal of Glaciology 2018/05 [Refereed][Not invited]
     Research paper (scientific journal) 
    Unlike in most other regions, Karakoram glaciers are either stable or advancing, a phenomenon known as the Karakoram anomaly. Despite studies of glacier surges and the derivation of surface velocity maps, the spatiotemporal variability of glacier dynamics still remains poorly understood, particularly in the Eastern Karakoram Range. We use Advanced Land Observing Satellite/the Phased Array type L-band Synthetic Aperture Radar (ALOS/PALSAR)-1/2 data from 2007 to 2011 and 2014 to 2015 to examine detailed surface velocity patterns of the Siachen, Baltoro, Kundos, Singkhu and Gasherbrum Glaciers. The first three glaciers show considerable velocity variability (20–350 m a−1), with clear seasonal patterns. Although all glaciers, except for Baltoro, flow slowest in 2015, the velocity structures are individual and vary in space and time. In Gasherbrum Glacier, peak surge-phase velocities are seasonally modulated, with maxima in summers 2006 and 2007, suggesting surface melt plays an important role in maintaining the active phase. Given the relatively close proximity of these glaciers, we assume that surface melt timing and rates are comparable. We therefore argue that the observed spatiotemporal and interannual velocity patterns are determined by local and internal mechanisms, including englacial and subglacial hydrology, thermal processes and tributary configuration of each individual glacier.
  • FURUYA Masato, SUZUKI Takato, MAEDA Jun, HEKI Kosuke
    Earth Planets and Space 69 175  2017/12 [Refereed][Not invited]
     Research paper (scientific journal)
  • Youhei Kinoshita and Masato Furuya
    SOLA 13 79 - 84 2017/05 [Refereed][Not invited]
     Research paper (scientific journal) 
    Localized propagation delay signals associated with line-aligned convective cells were detected by the Synthetic Aperture Radar Interferometry (InSAR) technique on 25 August 2010 in Niigata prefecture. The maximum amplitude of the signal reached up to 22.5 cm, which was approximately equivalent to 29 mm anomaly in precipitable water vapor (PWV). The nationwide radar rainfall intensity captured the spatial distribution of hydrometeors on both land and sea, which was similar to that of the InSAR-derived water vapor field, suggesting that the convective cells were initiated on the Japan Sea to the west-southwest of the observation area. A numerical weather model (NWM) simulation with the grid spacing of 2.5 km reproduced line-aligned convective cells with 3 cm smaller maximum amplitude to that in InSAR. A NWM simulation that assimilates Global Navigation Satellite System (GNSS)-derived PWV data for four-dimensional variational assimilation enhanced the water vapor flux convergence at the surface, which improved the amplitude of the localized delay signals. The advantage of the unique water vapor observation by InSAR enabled us to assess the meso-gamma scale NWM reproducibility in terms of water vapor, which is one of the fundamental prognostic parameter for NWMs.
  • Masato Furuya, Kotar Fukui, Hajime Iida, Shoichiro Kojima, Takeshi Matsuoka
    Bulletin of Glaciological Research 35 7 - 17 2017/05 [Refereed][Not invited]
     Research paper (scientific journal)
  • Dynamics of surge-type glaciers in Alaska-Yukon revealed by Synthetic Aperture Radar
    ABE Takahiro, FURUYA Masato
    Seppyo 78 (6) 425 - 438 2016/11 [Refereed][Not invited]
     Research paper (scientific journal)
  • Yuji Himematsu and Masato Furuya
    Earth Planets and Space 68 169  2016/10 [Refereed][Not invited]
     Research paper (scientific journal) 
    Series of earthquakes including three M w > 6 earthquakes occurred in Kumamoto prefecture in the middle of the Kyushu island, Japan. In order to reveal the associated crustal deformation signals, we applied offset tracking technique to ALOS-2/PALSAR-2 data covering three M w > 6 earthquakes and derived the 3D displacements around the epicenters. We could identify three NE–SW trending displacement discontinuities in the 3D displacements that were consistent with the surface location of Futagawa and Hinagu fault system. We set three-segment fault model whose positions matched the displacement discontinuities, and estimated the slip distributions on each segment from the observed pixel-offset data. Whereas right-lateral slip was dominant in the shallower depth of the larger segments, normal fault slip was more significant at a greater depth of the other segment. The inferred configuration and slip distribution of each segment suggest that slip partitioning under oblique extension stress regime took place during the 2016 Kumamoto earthquake sequence. Moreover, given the consistent focal mechanisms derived from both the slip distribution model and seismology, the significant non-double couple components in the focal mechanism of the main shock are due to simultaneous ruptures of both strike-slip and normal faulting at the distinct segments.
  • T. Abe, M. Furuya and D. Sakakibara
    The Cryosphere 10 1427 - 1432 2016/07 [Refereed][Not invited]
     Research paper (scientific journal) 
    Surge-type glaciers repeat their short active phase and their much longer quiescent phase usually every several decades or longer, but detailed observations of the evolution cycles have been limited to only a few glaciers. Here we report three surging episodes in 1989, 2001, and 2013 at Donjek Glacier in the Yukon, Canada, indicating remarkably regular and short repeat cycles of 12 years. The surging area is limited within the  ∼ 20 km section from the terminus, originating in an area where the flow width significantly narrows downstream, suggesting a strong control of the valley constriction on the surge dynamics.
  • Jun Maeda, Takato Suzuki, Masato Furuya, Kosuke Heki
    Geophysical Research Letters 43 (4) 1419 - 1425 2016/02 [Refereed][Not invited]
     Research paper (scientific journal) 
    Kilometer-scale fine structures of midlatitude sporadic E (Es) plasma patches have been directly imaged for the first time by an interferogram derived from L band Advanced Land Observation Satellite/Phased Array-type L band Synthetic Aperture Radar data obtained over southwestern Japan. The synthetic aperture radar interferogram captured the eastern part of a large-scale frontal structure of daytime midlatitude Es which spans over 250 km in the east-northeast to west-southwest direction. Fine structures are characterized by frontal and disc-shaped patches which are elongated in the same direction as the large-scale frontal structure. Length and width of the disc-shaped patches are 10–20 km and 5–10 km, respectively, and they are quasi-periodically located with a typical separation of 10–15 km. The Kelvin-Helmholtz instability with the vertical shear of zonal winds is considered to be the most likely candidate for the generation mechanism of the frontal patch and disc-shaped patches aligned in the zonal direction.
  • Takatoshi Yasuda, Masato Furuya
    Journal of Geophysical Research, Earth Surface 120 2015/11 [Refereed][Not invited]
     Research paper (scientific journal) 
    Here we examine 31 glaciers in the West Kunlun Shan of the northwestern Tibetan Plateau and identify 9 as surge type. The method is based on satellite synthetic aperture radar and Landsat optical images, the former going back to 1992, the latter to 1972. To identify surge-type glaciers, we consider temporal changes in velocity, changes in glacier terminus position, propagation of a surge bulge, presence of looped and/or contoured medial moraines, and extensive crevassing. Other than the nine surge-type glaciers, we identify two that have likely surged, and six that may be surge type. But no glacier surges more than once during the observation period, meaning that the recurrence interval exceeds 42 years. In addition, we examine the evolution of the surface velocities at two surging glaciers with the unprecedented temporal resolution of down to 11 days over ∼7 years. The results show clear seasonal modulations by as much as ∼200% in early winter against those in early summer. This seasonal modulation in surface velocity suggests the presence of surface meltwater that reroutes through the englacial and subglacial drainage systems. Thus, our findings suggest that the hydrological processes originating in the surface meltwater play an important role in maintaining the yearlong active surging phase.
  • T. Abe, M. Furuya and D. Sakakibara
    The Cryosphere Discuss 9 5943 - 5955 2015/11 [Refereed][Not invited]
     Research paper (scientific journal)
  • Muhammad Usman and Masato Furuya
    Earth Planets and Space 67 2015/09 [Refereed][Not invited]
     Research paper (scientific journal) 
    The Quetta Syntaxis in western Baluchistan, Pakistan, is the result of an oroclinal bend of the western mountain belt and serves as a junction for different faults. As this area also lies close to the left-lateral strike-slip Chaman fault, which marks the boundary between the Indian and Eurasian plates, the resulting seismological behavior of this regime is very complex. In the region of the Quetta Syntaxis, close to the fold and thrust belt of the Sulaiman and Kirthar Ranges, an earthquake with a magnitude of 6.4 (Mw) occurred on October 28, 2008, which was followed by a doublet on the very next day. Six more shocks associated with these major events then occurred (one foreshock and five aftershocks), with moment magnitudes greater than 4. Numerous researchers have tried to explain the source of this sequence based on seismological, GPS, and Environmental Satellite (ENVISAT)/Advanced Synthetic Aperture Radar (ASAR) data. Here, we used Advanced Land Observing Satellite (ALOS)/Phased Array-type L-band Synthetic Aperture Radar (PALSAR) InSAR data sets from both ascending and descending orbits that allow us to more completely detect the deformation signals around the epicentral region. The results indicated that the shock sequence can be explained by two right-lateral and two left-lateral strike-slip faults that also included reverse slip. The right-lateral faults have a curved geometry. Moreover, whereas previous studies have explained the aftershock crustal deformation with a different fault source, we found that the same left-lateral segment of the conjugate fault was responsible for the aftershocks. We thus confirmed the complex surface deformation signals from the moderate-sized earthquake. Intra-plate crustal bending and shortening often seem to be accommodated as conjugate faulting, without any single preferred fault orientation. We also detected two possible landslide areas along with the crustal deformation pattern.
  • Y. Himematsu and M. Furuya
    Tectonophysics 2015/06 [Refereed][Not invited]
     Research paper (scientific journal) 
    In July 2007, an earthquake swarm initiated in northern Tanzania near Lake Natron and lasted for about two months. Mt. Oldoinyo Lengai, located to the southwest of the swarm, began to erupt effusively about a month prior to the swarm, and increased its eruption intensity on September when the swarm almost ceased. Several previous studies have already reported the crustal deformation signals associated with the swarm using Interferometric Synthetic Aperture Radar (InSAR). However, nearly all the published data are based on the C-band ENVISAT/ASAR images acquired only from the descending path. We use the L-band ALOS/PALSAR images acquired from both ascending and descending paths, which allow us to examine the deformation signals in more detail. In addition to the InSAR data, we employ the offset-tracking technique to detect the signals along the azimuth direction. Using InSAR and offset-tracking data, we obtain the full 3D displacement fields associated with the episode. Besides the horizontal extension and subsidence signals due to the dike intrusion as already reported, the inferred full 3D displacements further indicate that the subsiding zone was horizontally moving by ~ 48 cm toward SSW. To explain the displacements, we performed fault source modeling, assuming an elastic half space. The fault slip distribution indicates that the contribution of the strike–slip component is about 20% of total moment release. Because almost all the focal mechanisms of earthquakes during the 2007 event indicate nearly pure normal faulting, aseismic strike–slip must have been responsible for the horizontal movement of the subsiding zone. The strike–slip at the shallowest depths suggests the presence of transtensive stress, which seems to be reasonable to generate the relay zones that are widely observed in the East African Rift. We also confirmed that the stress changes due to the dike intrusion were consistent with the inferred fault slip distributions.
  • T. Abe and M. Furuya
    The Cryosphere 9 1183 - 1190 2015/06 [Refereed][Not invited]
     Research paper (scientific journal) 
    Glacier surges often initiate in winter, but the mechanism remains unclear in contrast to the well-known summer speed-up at normal glaciers. To better understand the mechanism, we used radar images to examine spatial-temporal changes in the ice velocity of surge-type glaciers near the border of Alaska and the Yukon, focusing on their quiescent phase. We found significant accelerations in the upstream region from autumn to winter, regardless of surging episodes. Moreover, the winter speed-up propagated from upstream to downstream. Given the absence of surface meltwater input in winter, we suggest the presence of water storage near the base that does not directly connect to the surface, yet can promote basal sliding through increased water pressure. Our findings have implications for the modelling of glacial hydrology in winter, which may help us better understand glacier dynamics.
  • T. Abe and M. Furuya
    The Cryosphere Discuss 8 2611 - 2635 2014/05 [Refereed][Not invited]
     Research paper (scientific journal)
  • Y. Kinoshita, M. Shimada, and M. Furuya
    Geophysical Research Letters 40 2013/09 [Refereed][Not invited]
     Research paper (scientific journal) 
    This study reports the first detection and analysis of a localized water vapor distribution obtained using interferometric synthetic aperture radar (InSAR) during the Seino heavy rain episode. The InSAR data retrieved during the ALOS/PALSAR emergency observations for the event revealed a radar line-of-sight (LOS) change of up to 130 mm within 10 km. Based on the signal, we estimated the three-dimensional water vapor distribution using the ray-tracing method, which indicated a column of nearly saturated water vapor within a 10 km2 area reaching from the surface to 9000 m above ground level. To geophysically confirm this signal, Weather Research and Forecasting (WRF) model simulations were performed, revealing a deep convection that was initiated by orographic lift caused by the Yoro Mountains. Another simulation that did not include the Yoro Mountains did not produce a deep convection. The WRF simulation also suggested that the effect of hydrometeors can account for approximately 20% of the maximum LOS change but this effect is even more localized than the effect of water vapor.
  • Kinoshita, Y., M. Furuya, T. Hobiger, and R. Ichikawa
    J. Geodesy 87 (3) 267 - 277 2013/03 [Refereed][Not invited]
     Research paper (scientific journal) 
    Interferometric synthetic aperture radar phase data include not only signals due to crustal movements, but also those associated with microwave propagation delay through the atmosphere. In particular, the effect of water vapor can generate apparent signals in the order of a few centimeters or more, and prevent us from detecting such geophysical signals as those due to secular crustal deformation. To examine if and to what extent numerical weather model (NWM) outputs are helpful to reduce the tropospheric delay signals at spatial scales of 5–50 km wavelengths, we compared three approaches of tropospheric signal reduction, using 54 interferograms in central Hokkaido, Japan. The first approach is the conventional topography-correlated delay correction that is based on the regional digital elevation model (DEM). The second approach is based on the Japan Meteorological Agency’s operational meso-scale analysis model (MSM) data, where we compute tropospheric delays and subtract them from the interferogram. However, the MSM data are available at predefined epochs and their spatial resolution is about 10 km; therefore, we need to interpolate both temporally and spatially to match with interferograms. Expecting to obtain a more physically plausible reduction of the tropospheric effects, we ran a 1-km mesh high-resolution numerical weather model WRF (Weather Research and Forecasting model) by ourselves, using the MSM data as the initial and boundary conditions. The third approach is similar to the second approach, except that we make use of the WRF-based tropospheric data. Results show that if the topography-correlated phases are significant, both the conventional DEM-based approach and the MSM-based approach reveal comparable performances. However, when the topography-correlated phases are insignificant, none of the approaches can efficiently reduce the tropospheric phases. Although it could reduce the tropospheric signals in a local area, in none of the case studies did the WRF model produce the “best” performance. Whereas the global atmospheric model outputs are shown to be effective in reducing long-wavelength tropospheric signals, we consider that further improvements are needed for the initial and boundary condition data for high-resolution NWM, so that the NWM-based approach will become more reliable even in the case of a non-stratified troposphere.
  • Abe, T., M. Furuya, and Y. Takada
    Bull. Seismo. Soc. America 103 (1) 507 - 518 0037-1106 2013/02 [Refereed][Not invited]
     Research paper (scientific journal)
  • Minami Muto, Masato Furuya
    Remote Sensing and Environment 139 50 - 59 2013 [Refereed][Not invited]
     Research paper (scientific journal) 
    The Patagonian Ice Fields are known to have undergone rapid retreat of frontal positions and significant thinning of its glaciers over the past decades. However, surface velocities have been measured at only a few of these glaciers. Thus, it remains uncertain if and to what extent the glacier dynamics has changed over time and contributed to ice loss in these ice fields. In this study, we examine the temporal evolution of flow velocities and ice-front positions at eight major glaciers in the Southern Patagonian Ice Field (SPI; Hielo Patagónico Sur) by using Advanced Synthetic Aperture Radar (ASAR) images from the Environmental Satellite (Envisat) launched in 2002 by the European Space Agency and Advanced Land Observation Satellite/Phased Array-type L-band Synthetic Aperture Radar (ALOS/PALSAR) data recorded from 2002 to 2011. The examined eight glaciers include Glaciar Jorge Montt, Occidental, Pio XI (or Brüggen), O'Higgins, Viedma, Upsala, Perito Moreno, and Grey. Not all the glaciers revealed significant changes in frontal positions and flow velocities in the study period. We detected significant temporal velocity changes at Glaciar Upsala, Jorge Montt, Occidental, and Pio XI. Among these four glaciers, Glaciars Upsala, Jorge Montt, and Occidental revealed significant acceleration and terminus retreat and were undergoing dynamic-thinning. The markedly different absolute velocities but equally large longitudinal near-terminus stretching at the three glaciers support a calving model based on crevasse-depth criteria, which predict a calving position where crevasse-depths are equal to ice thickness; crevasse-depths are controlled by the longitudinal stretching rate. Meanwhile, Glaciar Pio XI revealed complex spatial and temporal evolution in surface velocities without significant retreat, and its dynamics remains enigmatic.
  • Takatoshi Yasuda, Masato Furuya
    Remote Sensing and Environment 128 87 - 106 0034-4257 2013 [Refereed][Not invited]
     Research paper (scientific journal)

MISC

Awards & Honors

  • 2000   The Tsuboi Prize of the Geodetic Society of Japan
       japan
  • 2004   Best paper award
       japan
  • 2010   ESPEC Prize for the Encouragement of Environmental Studies
       japan

Research Grants & Projects

  • Post-wildfire ground deformation over permafrost area: detection and modeling of spatial-temporal changes
    MEXT:Grand-in-aid for scientific research, Kiban (C)
    Date (from‐to) : 2019/04 -2022/03 
    Author : FURUYA Masato
  • Extreme Episodes in the Atmosphere viewed by InSAR
    Date (from‐to) : 2018/04 -2020/03 
    Author : FURUYA Masato
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(B))
    Date (from‐to) : 2007 -2009 
    Author : Masato FURUYA
     
    東京大学->北海道大学Using SAR data, we detected crustal deformation signals associated with several inland earthquakes in and around continental plate boundaries. All the data revealed unexpected signals that could not be predicted from the prompt seismological estimates of the fault sources, and thus would be overlooked if SAR were not used. We discovered a long-lasting afterslip due to the M5 earthquake at the Chaman fault, Afghanistan. All the events, including the 1996 Onikobe, 2007 Chuetsu-oki, 2008 Iwate-Miyagi, 2008 Yutian, 2008 Wenchuan, revealed complex crustal displacements that could not be explaine...

Educational Activities

Teaching Experience

  • 特別実習Ⅰ
    開講年度 : 2017
    課程区分 : 修士課程
    開講学部 : 理学院
  • Advanced Course in Remotesensing Applications
    開講年度 : 2017
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : リモートセンシング,人工衛星,遠隔探査 remote sensing
  • Inter-Graduate School Classes(General Subject):Natural and Applied Sciences
    開講年度 : 2017
    課程区分 : 修士課程
    開講学部 : 大学院共通科目
    キーワード : 北極、地球観測
  • Advanced Crustal Dynamics
    開講年度 : 2017
    課程区分 : 修士課程
    開講学部 : 理学院
    キーワード : 合成開口レーダー(SAR)、InSAR、Pixel offset、地震、火山、氷河氷床、電離層
  • Laboratory Work in Earth and Planetary Sciences IV
    開講年度 : 2017
    課程区分 : 学士課程
    開講学部 : 理学部
    キーワード : 岩石学, 火山学, 地球化学, 火山岩, マグマ,全球衛星測位システム, GEONET, 合成開口レーダー, 合成開口レーダー干渉法, データ処理
  • Freshman Seminar
    開講年度 : 2017
    課程区分 : 学士課程
    開講学部 : 全学教育
    キーワード : 有珠山、地殻変動、合成開口レーダ、SAR、宇宙測地学、人工衛星、Linux
  • Space Geodesy
    開講年度 : 2017
    課程区分 : 学士課程
    開講学部 : 理学部
    キーワード : 人工衛星,全地球測位システム,超長基線電波干渉法,衛星レーザー測距,衛星高度計,干渉合成開口レーダー,衛星間測距,座標系,地球回転,プレート運動,地殻変動,重力,ジオイド,リモートセンシング,最小二乗法

Committee Membership

  • 2016/07 - Today   Earth Planets Space   Vice Editor-in-chief


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