Researcher Database

Heki Kosuke
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

Degree

  • Master of Science(The University of Tokyo)
  • Doctor of Science (University of Tokyo)(The University of Tokyo)

URL

J-Global ID

Research Interests

  • 宇宙測地学   地球惑星物理学   Space Geodesy   Earth and Planetary Physics   

Research Areas

  • Natural sciences / Solid earth science

Academic & Professional Experience

  • 2001 - 2004 同 教授 2002 - 2004 国立天文台水沢観測センター長併任 教授
  • 2001 - 2004 Professor
  • 2004 - 北海道大学教授 教授
  • 2004 - Professor
  • 1994 - 2001 National Astronomical Observatory of Japan
  • 1994 - 2001 Associate Professor

Education

  •        - 1984  The University of Tokyo
  •        - 1984  The University of Tokyo  Graduate School, Division of Science
  •        - 1981  The University of Tokyo
  •        - 1981  The University of Tokyo  Graduate School, Division of Science
  •        - 1979  The University of Tokyo  Faculty of Science
  •        - 1979  The University of Tokyo  Faculty of Science

Association Memberships

  • アメリカ地球物理連合   日本地震学会   日本測地学会   測地学会   アジアオセアニア地球科学協会   地震学会   American Geophysical Union   Seismological Society of Japan   Geodetic Society of Japan   Asia Oceania Geoscience Society   

Research Activities

Books etc

  • 地球が丸いって本当ですか 測地学者へ50の質問
    朝日新聞社 2004

Works

  • 測地学に関する一般啓発書の執筆(四人の共同執筆)
    2003 -2004

MISC

  • Yu Morishita, Kosuke Heki  EARTH AND PLANETARY SCIENCE LETTERS  272-  (3-4)  677  -682  2008/08  [Not refereed][Not invited]
     
    El Nino and La Nina are known to bring about characteristic patterns of anomalous precipitation in various regions of the world. We extracted temporary and regional gravity changes from monthly gravity fields recovered by the GRACE satellites, and converted them to the changes in surface mass, possibly ground or Subsurface water in land area. Such mass changes in the 2006-2007 El Nino and 2005-2006 La Nina episodes agreed well with precipitation anomaly patterns inferred from meteorological records in tens of past such episodes. We further compared them with anomalies of soil moisture numerically Simulated by integrating monthly precipitation and evapotranspiration. They agree quantitatively with the GRACE data, Suggesting that temporal changes in terrestrial water storage in low-latitude region are largely governed by precipitation. This study demonstrates the potential of satellite gravimetry as a sensor of inter-annual climate changes. (c) 2008 Elsevier B.V. All rights reserved.
  • H. Noda, K. Heki, H. Hanada  ADVANCES IN SPACE RESEARCH  42-  (2)  358  -362  2008/07  [Not refereed][Not invited]
     
    The measurement of the rotation of the Moon is one of the key techniques to get the information of the internal structure. For this purpose, we proposed a small telescope experiment on the surface of the Moon in which motion of stars are utilized for the estimation of the rotation parameter. This paper describes results of simulation of observation, in which star trajectories observed are decomposed to librations, polar motion, and the precession and the amplitude and phase of each component are estimated. The standard deviation of the parameter estimation becomes nearly 1 ms of arc, which will be better than the Lunar Laser Ranging observation. From the viewpoints of accuracy of observation, thermal condition, and electric power generation, the instrument should be placed where the much sunshine is achieved on the lunar polar region. (C) 2008 Published by Elsevier Ltd on behalf of COSPAR.
  • 火星の真の極移動に伴う地殻変動について
    測地学会誌  54-  279  -282  2008  [Not refereed][Not invited]
  • J. Geophys. Res.  113-  B11402  2008  [Not refereed][Not invited]
  • Ionospheric hole behind an ascending rocket observed with a dense GPS array
    Tomoaki Furuya, Kosuke Heki  EARTH PLANETS AND SPACE  60-  (3)  235  -239  2008  [Not refereed][Not invited]
     
    An ascending liquid-fuel rocket is known to make a hole in the ionosphere, or localized electron depletion, by leaving behind large amounts of neutral molecules (e.g. water) in the exhaust plume. Such a hole was made by the January 24, 2006 launch of an H-IIA rocket from Tanegashima, Southwestern Japan, and here we report its observation with a dense array of Global Positioning System receivers as a sudden and temporary decrease of total electron content. The observed disturbances have been compared with a simple numerical model incorporating the water diffusion and chemical reactions in the ionosphere. The substantial vanishing of the ionosphere lasted more than one hour, suggesting its application as a window for ground-based radio astronomical observations at low frequencies.
  • Crustal deformation of Mars associated with the true polar wander
    J. Geodetic Society of Japan  54-  279  -282  2008  [Not refereed][Not invited]
  • Ryoko Ogawa, Kosuke Heki  GEOPHYSICAL RESEARCH LETTERS  34-  (6)  L06313-doi:10.1029/2007GL029340  2007/03  [Not refereed][Not invited]
     
    Earthquakes are accompanied with mass redistributions and cause changes in gravity field and shape of geoid, an equipotential surface coincident with the mean sea surface. Such coseismic changes were detected by satellite gravimetry after the 2004 Sumatra-Andaman Earthquake, but little has been known on what happens on geoid after the earthquake. Here we report slow postseismic recovery of coseismic geoid depression from satellite measurements. This cannot be explained with simple afterslip or viscous relaxation of Maxwellian upper mantle. It suggests the relaxation of coseismic dilatation and compression by the diffusion of supercritical H2O abundant in the upper mantle. Such a self-healing system of coseismic geoid undulations, a brand-new role of water in mantle, would significantly reduce the amount of permanent shifts of the Earth's rotation axis by earthquakes.
  • 小川 涼子, 日置 幸介  測地学会誌  52-  (4)  297  -308  2007  [Not refereed][Not invited]
  • Secular, transient and seasonal crustal movements in Japan from a dense GPS array: implication for plate dynamics in convergent boundaries
    The Seismogenic Zone of Subduction Thrust Faults  0-  512  -539  2007  [Not refereed][Not invited]
  • 日置 幸介  測地学会誌  52-  (4)  319  -328  2007  [Not refereed][Not invited]
  • Kosuke Heki, Yuichi Otsuka, Nithiwatthn Choosakul, Narong Hemmakorn, Tharadol Komolmis, Takashi Maruyama  JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH  111-  (B9)  B09313-doi:10.1029/2005JB004202  2006/09  [Not refereed][Not invited]
     
    [ 1] Near-field coseismic perturbations of ionospheric total electron content (TEC), caused by direct acoustic waves from focal regions, can be observed with Global Positioning System (GPS). They appear 10 - 15 min after the earthquake with typical periods of similar to 4 - 5 min and propagate as fast as similar to 1 km/s toward directions allowed by ambient geomagnetic fields. Ionospheric disturbance, associated with the 2004 December 26 great Sumatra-Andaman earthquake, was recorded with nine continuous GPS receiving stations in Indonesia and Thailand. Here we explore the possibility to constrain the rupture process of the earthquake with the observed ionospheric disturbances. We assumed linearly distributed point sources along the zone of coseismic uplift extending similar to 1300 km from Sumatra to the Andaman Islands that excited acoustic waves sequentially as the rupture propagate northward by 2.5 km/s. TEC variations for several satellite-receiver pairs were synthesized by simulating the propagation of acoustic waves from the ground to the ionosphere and by integrating the TEC perturbations at intersections of line of sights and the ray paths. The TEC perturbations from individual point sources were combined using realistic ratios, and the total disturbances were compared with the observed signals. Prescribed ratios based on geodetically inferred coseismic uplifts reproduced the observed signals fairly well. Similar calculation using a rupture propagation speed of 1.7 km/s degraded the fit. Suppression of acoustic waves from the segments north of the Nicobar Islands also resulted in a poor fit, which suggests that ruptures in the northern half of the fault were slow enough to be overlooked in short-period seismograms but fast enough to excite atmospheric acoustic waves. Coseismic ionospheric disturbance could serve as a new indicator of faulting sensitive to ruptures with timescale up to 4 - 5 min.
  • Kosuke Heki  GEOPHYSICAL RESEARCH LETTERS  33-  (14)  L14303-doi:10.1029/2006GL026249  2006/07  [Not refereed][Not invited]
     
    The Japanese dense array of Global Positioning System recorded ionospheric disturbances as changes in Total Electron Content similar to 12 minutes after the September 1 2004 eruption of the Asama Volcano, Central Japan. The disturbance had a period of one and a quarter minutes and propagated as fast as similar to 1.1 km/s, suggesting its origin as the acoustic wave generated by the explosion. By comparing the disturbance amplitudes with those by a surface mine blast with a known energy, the overall Asama explosion energy is inferred to be about 2 x 10(14) J.
  • K Heki, JS Ping  EARTH AND PLANETARY SCIENCE LETTERS  236-  (3-4)  845  -855  2005/08  [Not refereed][Not invited]
     
    Coseismic disturbances in ionosphere have been observed after recent thrust earthquakes off the Pacific coast of Japan, with a dense Global Positioning System array. Positive pulses in electron content, as large as several times 10(15) electrons/m(2) and as long as 4-5 min, emerge similar to 10 min after earthquakes and propagate horizontally with apparent velocity of similar to 1 km/s, close to the sound velocity at the ionospheric height. They may have been excited by coseismic uplifts of the sea surface initially as upward propagating compressive pulses of atmosphere, which were gradually refracted to propagate horizontally in ionosphere. The propagation has strong north-south asymmetry, and interaction between the movements of charged particles in acoustic waves and geomagnetic fields might have selectively attenuated the northward propagating disturbances. (c) 2005 Elsevier B.V. All rights reserved.
  • S Goossens, PNAM Visser, K Heki, BAC Ambrosius  EARTH PLANETS AND SPACE  57-  (11)  1127  -1132  2005  [Not refereed][Not invited]
     
    High-resolution gravity anomalies on the surface of the Moon are determined from Lunar Prospector tracking data residuals. By means of a benchmark test the recovery method is validated with respect to the orbit determination and gravity field recovery strategy. Tracking data for the entire extended mission of Lunar Prospector, during which the satellite flew at an average altitude of 30 km above the lunar Surface, have been completely and independently processed and orbits have been determined. Using tracking data residuals from these precise orbits, adjustments to the a priori gravity field model have been created for Mare Serenitatis. The results for Mare Serenitatis with the local recovery are comparable to global recovery results, yet faster and more efficient with a possibility to increase the resolution.
  • Application of a PZT telescope to in situ lunar orientation measurement (ILOM)
    H Hanada, K Heki, H Araki, K Matsumoto, H Noda, N Kawano, T Tsubokawa, S Tsuruta, S Tazawa, K Asari, Y Kono, T Yano, N Gouda, T Iwata, T Yokoyama, H Kanamori, K Funazaki, T Miyazaki  Window on the Future of Geodesy  128-  163  -168  2005  [Not refereed][Not invited]
     
    We are proposing a selenodetic mission, e.g. In situ Lunar Orientation Measurement (ILOM) to study lunar rotational dynamics by direct observations of the lunar physical libration and the free librations from the lunar surface with an accuracy of 1 millisecond of arc in the post-SELENE project. Year-long trajectories of the stars provide information on various components of the physical librations and they can also be used to possibly detect the lunar free librations in order to investigate the lunar mantle and the liquid core. The PZT on the moon is similar to that used for latitude observations of the Earth except the half mirror above the objective, a CCD with high well capacity, and the heater beneath the mercury pool. Although a star position on the focal plane does not change even if the telescope inclines in principle, the tilt of the telescope affects the star position due to aberrations of the objective in the actual case. We obtained the relation between the deviation of the star position in CCD and the tilt of the telescope by ray tracing method and found that the effect of the tilt less than 100 arc seconds upon the star position does not exceed 1 mas. Thermal test of a tube made of CFRP showed that the tube did not incline by more than 100 seconds of arc even in the conditions of the lunar surface. We have a prospect to attain an accuracy of positioning of better than 1 mas from simulated experiments in laboratory using a CCD.
  • T Sugano, K Heki  GEOPHYSICAL RESEARCH LETTERS  31-  (24)  L24703-doi:10.1029/2004GL022059  2004/12  [Not refereed][Not invited]
     
    [ 1] The Lunar Prospector line-of-sight acceleration data after terrain correction have been inverted to the high-resolution Bouguer gravity anomalies of the lunar nearside. Lithospheric thicknesses of the early Moon were investigated by comparing the gravity anomalies of craters and impact basins of various dimensions. The lithosphere was already thick enough to support craters with diameters up to 300 km in the Pre-Nectarian and Nectarian Periods. Degree of isostatic compensation of larger impact basins suggested lithospheric thickness of 20-60 km at that time, which depended more on localities rather than age differences.
  • T Sugano, K Heki  GEOPHYSICAL RESEARCH LETTERS  31-  (24)  L24703-doi:10.1029/2004GL022059  2004/12  [Not refereed][Not invited]
     
    [ 1] The Lunar Prospector line-of-sight acceleration data after terrain correction have been inverted to the high-resolution Bouguer gravity anomalies of the lunar nearside. Lithospheric thicknesses of the early Moon were investigated by comparing the gravity anomalies of craters and impact basins of various dimensions. The lithosphere was already thick enough to support craters with diameters up to 300 km in the Pre-Nectarian and Nectarian Periods. Degree of isostatic compensation of larger impact basins suggested lithospheric thickness of 20-60 km at that time, which depended more on localities rather than age differences.
  • K Heki  EARTH AND PLANETARY SCIENCE LETTERS  219-  (1-2)  13  -20  2004/02  [Not refereed][Not invited]
     
    Observation of tectonic erosion [Von Huene and Scholl, Rev. Geophys. 29 (1991) 279-316] in a subduction zone has been difficult as it leaves little geological and geophysical evidence. Three-dimensional velocity profiles of crustal movement obtained by Global Positioning System across NE and SW Japan agree well with those predicted by the elastic loading of the subducting slabs. However, vertical velocities in the NE Japan foreare show significant negative deviation (relative subsidence). This may indicate loss of material at the plate interface that can be attributed to the erosion of the upper plate by the underthrusting slab (basal subduction erosion). The estimated rate (15 mm/yr down to a slab depth of 90 km) is somewhat faster than the geological average; the erosion speed may be variable being controlled by the surface roughness of subducting slabs. (C) 2003 Elsevier B.V. All rights reserved.
  • T Sugano, K Heki  EARTH PLANETS AND SPACE  56-  (1)  81  -86  2004  [Not refereed][Not invited]
     
    Study of the lunar gravity anomaly has not been straightforward since direct tracking data of lunar satellites are available only at its nearside. In such a case, direct inversion of the line-of-sight acceleration data into surface mass distribution has several merits, e.g., (1) high resolution can be attained without relying on artificial constraints, (2) short computation time by estimating regional parameter sets stepwise. After confirming the validity of the method using synthesized data, we processed the line-of-sight acceleration data of the Lunar Prospector extended low-altitude mission. The obtained gravity anomaly map of the lunar nearside has resolution as high as 0.8degrees x 0.8degrees, equivalent to 225th degree/order of spherical harmonies, with less spurious signatures than past studies. To take advantage of the high resolution, we calculate mass deficits for 92 medium-sized craters (50-300 km in diameter), and confirmed that they are nearly proportional to 2.5 power of crater diameter.
  • Jinsong Ping, Koji Matsumoto, Kosuke Heki, Akinori Saito, Philip Callahan  MARINE GEODESY  27-  (3-4)  741  -752  2004  [Not refereed][Not invited]
     
    The Jason-1 dual-frequency nadir ionosphere Total Electron Content (TEC) for 10-day cycles 1-67 is validated using absolute TEC measured by Japan's GPS Earth Observation Network (GEONET), or the GEONET Regional Ionosphere Map (RIM). The bias estimates (Jason-RIM) are small and statistically insignificant: 1.62 +/- 9 TECu (TEC unit or 10(16) electrons/m(2), 1 TECu = 2.2 mm delay at Ku-band) and 0.73 +/- 0.05 TECu, using the along-track difference and Gaussian distribution method, respectively. The bias estimates are -3.05 +/- 10.44 TECu during daytime passes, and 0.02 +/- 8.05 TECu during nighttime passes, respectively. When global Jason-1 TEC is compared with the Global Ionosphere Map (GIM) from the Center for Orbit Determination in Europe (or CODE) TEC, the bias (Jason-GIM) estimate is 0.68 +/- 1.00 TECu, indicating Jason-1 ionosphere delay at Ku-band is longer than GIM by 3.1 mm, which is at present statistically insignificant. Significant zonal distributions of biases are found when the differences are projected into a sun-fixed geomagnetic reference frame. The observed biases range from -7 TECu (GIM larger by 15.4 mm) in the equatorial region, to + 2 TECu in the Arctic region, and to + 7 TECu in the Antarctica region, indicating significant geographical variations. This phenomena is primarily attributed to the uneven and poorly distributed global GPS stations particularly over ocean and near polar regions. Finally, when the Jason-1 and TOPEX/Poseidon (T/P) TECs were compared during Jason-1 cycles 1-67 (where cycles 1-21 represent the formation flight with T/P, cycles 22-67 represent the interleave orbits), the estimated bias is 1.42 +/- 0.04 TECu. It is concluded that the offset between Jason/TOPEX and GPS (RIM or GIM) TECs is < 4 mm at Ku-band, which at present is negligible.
  • K Heki  STATE OF THE PLANET: FRONTIERS AND CHALLENGES IN GEOPHYSICS  150-  177  -196  2004  [Not refereed][Not invited]
     
    Global Positioning System (GPS) receivers have been deployed worldwide to study inter- and intraplate crustal motions and local deformations associated with earthquakes and volcanic activities. A dense array of GPS is also useful for studying seasonally changing load through periodic components in crustal movements. This article reviews observed and predicted seasonal crustal movements in the Japanese Islands, where both nationwide dense GPS array and meteorological sensor network are available. From comprehensive evaluation of various sources contributing to seasonal signals, the largest factor in Japan is found to be snow, weighing over 1000 kg per square meter in some regions. This is followed by various kinds of loads on the land area, such as atmosphere, soil moisture and water impoundment in reservoirs, and non-tidal ocean loads also cause certain seasonal signatures. Seasonal crustal deformations are calculated by synthesizing all these seasonal load changes, some of which are directly measured meteorologically and others are inferred through models. They are compared with real data observed by the dense GPS array in Japan, and their agreement was examined. The seasonal signals observed by GPS also include artifacts, such as those caused by atmospheric delay gradients and scale changes due to atmospheric refraction. We often discuss subtle crustal deformation signals, e.g. those associated with silent earthquakes, isolating them by removing secular and periodic components. Understanding seasonal signals and their interannual variability is crucial in removing these unwanted signals. The article discusses the Japanese case, but the methods proposed here will be useful worldwide to study seasonal mass redistributions. Dense GPS arrays may play a complementary role to satellite gravity missions in studying seasonal mass redistribution on the Earth in a regional scale.
  • K Heki  EARTH AND PLANETARY SCIENCE LETTERS  207-  (1-4)  159  -164  2003/02  [Not refereed][Not invited]
     
    Snow load along the western flank of the backbone range of the Japanese Islands causes seasonal crustal deformation. It perturbs the interseismic strain buildup, and may seasonally influence the seismicity in Japan. Intraplate earthquakes in northeastern Japan occur on reverse faults striking parallel with the snow-covered zone. In central and southwestern Japan, they occur on strike-slip faults striking either parallel with, or perpendicular to the snow cover. The snow load enhances compression at these faults, reducing the Coulomb failure stress by a few kPa. This is large enough to modulate the secular stress buildup of a few tens of kPa/yr. Past inland earthquakes with magnitudes greater than or equal to 7.0 that occurred in regions covered with snow in winter, tend to occur more in spring and summer than in autumn and winter, while those in the snow-free regions do not show such variation. Although its statistical significance is not strong due to limited number of past earthquakes, it suggests that the spring thaw enhances seismicity beneath the snow cover. (C) 2003 Elsevier Science B.V. All rights reserved.
  • An impact of estimating tropospheric delay gradients on tropospheric delay estimations in the summer using the Japanese nationwide GPS array
    , Jour. Geophysical Research  108-  (No.D10)  4315-doi:10.1029/2002JD002214  2003  [Not refereed][Not invited]
  • 雪どけは地震をトリガーするか
    月刊地球  Vol.25-  (No.2)  109  -113  2003  [Not refereed][Not invited]
  • Adv. Space Res.  31-  2377  -2382  2003  [Not refereed][Not invited]
  • Mare basalt mass correction for the lunar Bouguer gravity anomalies
    Proc. 36th ISAS Lunar Planet. Symp.  36-  141  -144  2003  [Not refereed][Not invited]
  • 月着陸船の超低高度周回時の追尾による高精度重力プロファイルの取得
    第24回太陽系科学シンポジウム集録  5  -8  2003  [Not refereed][Not invited]
  • Lunar global crustal analyis from topography and gravity anomalies based on upgraded correlation algorithm
    Proc. 36th ISAS Lunar Planet. Symp.  36-  145  -148  2003  [Not refereed][Not invited]
  • An impact of estimating tropospheric gradient on precise positioning in summer using the Japanese nationwide GPS array
    J. Geophys. Res.  108-  2335-doi:10.1029/2000JB000113  2003  [Not refereed][Not invited]

Awards & Honors

  • 2007 AGU Journal Highlight
  • 1996 第4回 測地学会賞 坪井賞
  • 1996 The 4th Tsuboi Prize, Geodetic Society of Japan (1996)

Research Grants & Projects

  • 測地学的手法による地球惑星物理の研究、宇宙測地技術の開発研究
    Date (from‐to) : 1983
  • Earth and Planetary Physics with Geodetic Approaches, R/D of Space Geodetic Techniques
    Date (from‐to) : 1983

Educational Activities

Teaching Experience

  • Advanced Course in Remote Sensing Applications
    開講年度 : 2018
    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
  • The World of Science and Technology
    開講年度 : 2018
    課程区分 : 学士課程
    開講学部 : 全学教育
    キーワード : 地球,惑星,陸水,海洋、気象、地震,火山,測地,地殻変動,重力、気候変動,人工衛星、シミュレーション
  • Physics of the Earth's Interior
    開講年度 : 2018
    課程区分 : 学士課程
    開講学部 : 理学部
    キーワード : 地球物理学 測地学 惑星科学 重力 潮汐 内部構造 月 地磁気 地球回転 ジオイド 宇宙測地技術


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