日本学士院

会員情報

 

氏名

長谷川昭（はせがわ　あきら）


 

所属部・分科

第2部第4分科

選定年月日

令和7年12月12日

専攻学科目

地震学

現職等

受賞等

〔国内〕

〔海外〕

 

外国アカデミー会員等

米国地球物理学連合フェロー（2008年）

主要な学術上の業績

長谷川　昭氏は、プレート沈み込み帯の典型である東北日本に高感度・高精度の地震観測網を構築し、得られた高品質データに見合う緻密な解析手法を開発することにより、沈み込み帯の地殻・マントル構造と地震・火山活動を世界のどこよりも高い解像度と精度で明らかにしてきました。スラブ内の二重深発地震面の発見に始まり、スラブ内の含水鉱物が脱水分解する深さでのスラブ内地震の集中発生の発見、プレート境界地震や内陸地震の断層面の強度が極めて弱いことを明らかにするなど、この分野で世界を先導する業績を挙げてきました。また一連の成果の帰結として、地震発生時にスラブから吐き出された水が重要な役割を果たしていることを示しました。更に、吐き出された水はマントルウェッジ内の上昇流に取り込まれて部分溶融域を生じ、最終的に地表の火山にまで到達するとする島弧火山の生成モデルを提案しました。このように、長谷川氏は、沈み込み帯の地殻・マントル構造と地震・火山活動を、高い解像度と精度で明らかにし、「プレート沈み込みに伴って移動する水」をキーワードに地学現象を理解する途を拓き、この分野の重要課題の解明に大きく貢献しました。

主要な著書・論文

著書

  1. Hasegawa, A. and J. Nakajima, Geophysical constraints on slab subduction and arc magmatism. In The State of the Planet: Frontiers and Challenges in Geophysics, Geophys. Monogr. Ser., 150, 81-94, AGU, Washington, D.C., 2004.
  2. 長谷川昭，佐藤春夫，西村太志，地震学，共立出版，2015.
  3. Hasegawa, A., J. Nakajima, and D. Zhao, Deep seismic structure, in Geology of Japan, The Geological Society, London, 339-370, 2016.

論文

  1. Hasegawa, A., N. Umino and A. Takagi, Double-planed structure of the deep seismic zone in the northeastern Japan arc, Tectonophysics, 47, 43-58, 1978.
  2. Hasegawa, A., N. Umino and A. Takagi, Double-planed deep seismic zone and upper-mantle structure in the northeastern Japan arc, Geophys. J. Roy. Astron. Soc., 54, 281-296, 1978.
  3. Hasegawa, A. and I. S. Sacks, Subduction of the Nazca plate beneath Peru as determined from seismic observation, J. Geophys. Res., 86, 4971-4980, 1981.
  4. Matsuzawa, T., N. Umino, A. Hasegawa and A. Takagi, Upper mantle velocity structure estimated from PS-converted wave beneath the northeastern Japan arc, Geophys. J. Roy. Astron. Soc., 86, 767-787, 1986.
  5. Hasegawa, A., D. Zhao, S. Hori, A. Yamamoto and S. Horiuchi, Deep structure of the northeastern Japan arc and its relationship to seismic and volcanic activity, Nature, 352, 683-689, 1991.
  6. Zhao, D., A. Hasegawa and S. Horiuchi, Tomographic imaging of P and S wave velocity structure beneath northeastern Japan, J. Geophys. Res., 97, 19909-19928, 1992.
  7. Hasegawa, A., A. Yamamoto, D. Zhao, S. Hori and S. Horiuchi, Deep structure of arc volcanoes as inferred from seismic observations, Phi. Trans. Roy. Soc. London A, 342, 167-178, 1993.
  8. Hasegawa, A. and A. Yamamoto, Deep, low-frequency microearthquakes in or around seismic low-velocity zones beneath active volcanoes in northeastern Japan, Tectonophysics, 233, 233-252, 1994.
  9. Hasegawa, A., A. Yamamoto, N. Umino, S. Miura, S. Horiuchi, D. Zhao and H. Sato, Seismic activity and deformation process of the crust within the overriding plate in the northeastern Japan subduction zone, Tectonophysics, 319, 225-239, 2000.

11. Nakajima, J. and A. Hasegawa, Estimation of thermal structure in the mantle wedge of northeastern Japan from seismic attenuation data, Geophys. Res. Lett., 30, https://doi.org/10.1029/2003GL017185, 2003.

  1. Hasegawa, A., J. Nakajima, N. Umino and S. Miura, Deep structure of the northeastern Japan arc and its implications for crustal deformation and shallow seismic activity, Tectonophysics, 403/1-4, 59-75, 2005.
  2. Nakajima, J., Y. Takei and A. Hasegawa, Quantitative analysis of the inclined low-velocity zone in the mantle wedge of northeastern Japan: A systematic change of melt-filled pore shapes with depth and its implications for melt migration, Earth Planet. Sci. Lett., 234, 59-70, 2005.
  3. Kita, S., T. Okada, J. Nakajima, T. Matsuzawa and A. Hasegawa, Existence of a seismic belt in the upper plane of the double seismic zone extending in the along-arc direction at depths of 70-100 km beneath NE Japan, Geophys. Res. Lett., 33, https://doi.org/10.1029/2006GL028239, 2006.
  4. Uchida, N., T. Matsuzawa, W. L. Ellsworth, K. Imanishi, T. Okada and A. Hasegawa, Source parameters of a M4.9 and its accompanying repeating earthquakes off Kamaishi, NE Japan -implications for the hierarchical structure of asperities and earthquake cycle, Geophys. Res. Lett., 34, L20313, https://doi.org/10.1029/2007GL031263, 2007.
  5. Hasegawa, A., J. Nakajima,  S. Kita, T. Okada, T. Matsuzawa and S. Kirby, Anomalous deepening of a belt of intraslab earthquakes in the Pacific slab crust under Kanto, central Japan: Possible anomalous thermal shielding, dehydration reactions, and seismicity caused by shallower cold slab material, Geophys. Res. Lett., 34, L09305, https://doi.org/10.1029/2007GL029616, 2007.
  6. Hasegawa, A, K. Yoshida and T. Okada, Nearly complete stress drop in the 2011 Mw9.0 off the Pacific coast of Tohoku Earthquake, Earth Planets Space, 63 (No. 7), 703-707, https://doi.org/10.5047/eps.2011.06.007, 2011.
  7. Hasegawa, A, K. Yoshida, Y. Asano, T. Okada, T. Iinuma and Y. Ito, Change in stress field after the 2011 great Tohoku-oki earthquake, Earth Planet. Sci. Lett., 355–356, 231–243, https://doi.org/10.1016/j.epsl.2012.08.042, 2012.
  8. Nakajima, J. and A. Hasegawa, Tremor activity inhibited by well-drained conditions above a megathrust, Nature Communications, 7, https://doi.org/10.1038/ncomms13863, 2016.
  9. Hasegawa, A. and J. Nakajima, Seismic imaging of slab metamorphism and genesis of intermediate-depth intraslab earthquakes, Progress Earth Planetary Science, https://doi.org/10.1186/s40645-017-0126-9, 2017.
  10. Yoshida, K. and A. Hasegawa, Hypocenter migration and seismicity pattern change in the 2011 Yamagata-Fukushima border, NE Japan, earthquake swarm caused by fluid movement and pore pressure change, J. Geophys. Res., 123. https://doi.org/10.1029/2018JB015468, 2018.
  11. Nakajima, J. and A. Hasegawa, Prevalence of shallow low-frequency earthquakes in the continental crust, J. Geophys. Res., 126, e2020JB021391.　https://doi.org/10.1029/2020JB021391, 2021.
  12. Nakajima, J. and A. Hasegawa, Prevalence of repeating earthquakes in the continental crust and subducting slabs: Implications for triggering of earthquakes by aseismic slip, J. Geophys. Res., 128, e2022JB024667. https://doi.org/10.1029/2022JB024667, 2023.

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