Organization
School of Science Lecturer
Title
Lecturer
External link
MATSUSHIMA MASAKI
News & Topics
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2020/05/29
Languages： Japanese
要点-月周回衛星「かぐや」[用語1]によって月全面から恒常的に宇宙空間に流出する炭素を発見-月は誕生時から炭素を含有していたことを示唆-月（と地球）の誕生・進化モデル（巨大衝突[用語2]説）について見直す契機となる概要大阪大学大学院理学研究科
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2014/05/08
Languages： Japanese
月探査機「かぐや」月磁場研究グループの九州大学大学院理学研究院・高橋太准教授と東京工業大学大学院理工学研究科・綱川秀夫教授（グループリーダー）らは衛星観測データを解析し、太古の月には地球と同じように大規模な磁場が存在していたこと、現在とは数十度異なる自転軸だったことを明らかにしました。現在の月には大規模な磁場はありません。本研究から、約40億年前の月中心部では溶けた鉄が活発に運動し磁場を発生していたことがわかりました。その磁極は離れた2箇所にあり、一つは現在の月北極付近にありますが、もう一つは数十度離れていました。磁極の位置は自転軸の極とほぼ一致する性質があり、月の自転軸はかつて今の位置から大きく離れていたことになります。このことは、月の形成と進化を明らかにする上で非常に重要な成果です。
Degree
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Doctor of Science ( Tokyo Institute of Technology )
Research Areas
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Natural Science / Solid earth sciences
Education
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Tokyo Institute of Technology School of Science
- 1986
Country： Japan
Professional Memberships
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地球電磁気・地球惑星圏学会
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American Geophysical Union
Papers
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Sho Sato, Shin’ya Nakano, Vincent Lesur, Masaki Matsushima, Takuto Minami, Hiroaki Toh
Earth, Planets and Space 2026.1
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Tülay Kaya-Eken, Yasuo Ogawa, Yoshiya Usui, Takafumi Kasaya, M. Kemal Tunçer, Yoshimori Honkura, Naoto Oshiman, Masaki Matsushima, Weerachai Siripunvaraporn
Geology 2025.12
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Effect of core electrical conductivity on core surface flow models Reviewed
Masaki Matsushima
Earth, Planets and Space 72 ( 1 ) 2020.12
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The BepiColombo–Mio Magnetometer en Route to Mercury Reviewed
W. Baumjohann, A. Matsuoka, Y. Narita, W. Magnes, D. Heyner, K.-H. Glassmeier, R. Nakamura, D. Fischer, F. Plaschke, M. Volwerk, T. L. Zhang, H.-U. Auster, I. Richter, A. Balogh, C. M. Carr, M. Dougherty, T. S. Horbury, H. Tsunakawa, M. Matsushima, M. Shinohara, H. Shibuya, T. Nakagawa, M. Hoshino, Y. Tanaka, B. J. Anderson, C. T. Russell, U. Motschmann, F. Takahashi, A. Fujimoto
Space Science Reviews 216 ( 8 ) 2020.12
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Takuto Minami, Shin’ya Nakano, Vincent Lesur, Futoshi Takahashi, Masaki Matsushima, Hisayoshi Shimizu, Ryosuke Nakashima, Hinami Taniguchi, Hiroaki Toh
Earth, Planets and Space 72 ( 1 ) 2020.12
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Probing the relationship between electrical conductivity and creep through upper crustal fluids along the western part of the North Anatolian Fault with three-dimensional magnetotellurics Reviewed
Mustafa Karaş, Sabri Bülent Tank, Yasuo Ogawa, Naoto Oshiman, Masaki Matsushima, Yoshimori Honkura
Tectonophysics 791 228561 - 228561 2020.9
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KAGUYA observation of global emissions of indigenous carbon ions from the Moon Reviewed International journal
Shoichiro Yokota, Kentaro Terada, Yoshifumi Saito, Daiba Kato, Kazushi Asamura, Masaki N. Nishino, Hisayoshi Shimizu, Futoshi Takahashi, Hidetoshi Shibuya, Masaki Matsushima, Hideo Tsunakawa
Science Advances 6 ( 19 ) 2020.5
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Decrease of the interplanetary magnetic field strength on the lunar dayside and over the polar region Reviewed
M. N. Nishino, Y. Saito, H. Tsunakawa, Y. Harada, F. Takahashi, S. Yokota, M. Matsushima, H. Shibuya, H. Shimizu, Y. Miyashita
Icarus 335 ( 1 ) 113392 2020.1
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Erratum: Core surface flow modelling with geomagnetic diffusion in a boundary layer Reviewed
Masaki Matsushima
Geophysical Journal International 215 ( 3 ) 1700 - 1700 2018.12
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Electromagnetic Ion Cyclotron Waves Detected by Kaguya and Geotail in the Earth's Magnetotail Reviewed
Tomoko Nakagawa, Masaki N. Nishino, Hideo Tsunakawa, Futoshi Takahashi, Hidetoshi Shibuya, Hisayoshi Shimizu, Masaki Matsushima, Yoshifumi Saito
Journal of Geophysical Research: Space Physics 123 ( 2 ) 1146 - 1164 2018.2
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Masaki N. Nishino, Yuki Harada, Yoshifumi Saito, Hideo Tsunakawa, Futoshi Takahashi, Shoichiro Yokota, Masaki Matsushima, Hidetoshi Shibuya, Hisayoshi Shimizu
Icarus 293 45 - 51 2017.9
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Electrical image of subduction zone beneath northeastern Japan Reviewed
Ichiki, Masahiro, Ogawa, Yasuo, Kaida, Toshiki, Koyama, Takao, Uyeshima, Makoto, Demachi, Tomotsugu, Hirahara, Satoshi, Honkura, Yoshimori, Kanda, Wataru, Kono, Toshio, Matsushima, Masaki, Nakayama, Takashi, Suzuki, Syuichi, Toh, Hiroaki
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH 120 ( 12 ) 7937 - 7965 2015.12
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Core surface flow modelling with geomagnetic diffusion in a boundary layer Reviewed
Masaki Matsushima
Geophysical Journal International 202 ( 3 ) 1495 - 1504 2015.9
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Hideo Tsunakawa, Futoshi Takahashi, Hisayoshi Shimizu, Hidetoshi Shibuya, Masaki Matsushima
Journal of Geophysical Research E: Planets 120 ( 6 ) 1160 - 1185 2015.6
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Electrons on closed field lines of lunar crustal fields in the solar wind wake Reviewed
Masaki N. Nishino, Yoshifumi Saito, Hideo Tsunakawa, Futoshi Takahashi, Masaki Fujimoto, Yuki Harada, Shoichiro Yokota, Masaki Matsushima, Hidetoshi Shibuya, Hisayoshi Shimizu
Icarus 250 238 - 248 2015.4
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ELF magnetic fluctuations detected by Kaguya in deepest lunar wake associated with type-II protons Reviewed
Tomoko Nakagawa, Tatsuya Nakashima, Takuya Wada, Hideo Tsunakawa, Futoshi Takahashi, Hidetoshi Shibuya, Hisayoshi Shimizu, Masaki Matsushima, Yoshifumi Saito
EARTH PLANETS AND SPACE 67 2015.4
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Harmonics of whistler-mode waves near the Moon Reviewed
Yasunori Tsugawa, Yuto Katoh, Naoki Terada, Hideo Tsunakawa, Futoshi Takahashi, Hidetoshi Shibuya, Hisayoshi Shimizu, Masaki Matsushima
EARTH PLANETS AND SPACE 67 2015.3
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Reorientation of the early lunar pole Reviewed
Takahashi Futoshi, Tsunakawa Hideo, Shimizu Hisayoshi, Shibuya Hidetoshi, Matsushima Masaki
NATURE GEOSCIENCE 7 ( 6 ) 409 - 412 2014.6
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Structure of the ionized lunar sodium and potassium exosphere: Dawn-dusk asymmetry Reviewed
Yokota Shoichiro, Tanaka Takaaki, Saito Yoshifumi, Asamura Kazushi, Nishino Masaki N, Fujimoto Masaki, Tsunakawa Hideo, Shibuya Hidetoshi, Matsushima Masaki, Shimizu Hisayoshi, Takahashi Futoshi
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS 119 ( doi:10.1002/2013JE004529 ) 798 - 809 2014.4
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Group-standing of whistler-mode waves near the Moon Reviewed
Tsugawa, Y, Katoh, Y, Terada, N, Ono, T, Tsunakawa, H, Takahashi, F, Shibuya, H, Shimizu, H, Matsushima, M
J. Geophys. Res. Space phys. 119 ( DOI: 10.1002/2013JA019585 ) 2014.4
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Hideo Tsunakawa, Futoshi Takahashi, Hisayoshi Shimizu, Hidetoshi Shibuya, Masaki Matsushima
Icarus 228 35 - 53 2014.1
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Kaguya observation of the ion acceleration around a lunar crustal magnetic anomaly Reviewed
Shoichiro Yokota, Yoshifumi Saito, Kazushi Asamura, Masaki N. Nishino, Tadateru I. Yamamoto, Hideo Tsunakawa, Hidetoshi Shibuya, Masaki Matsushima, Hisayoshi Shimizu, Futoshi Takahashi, Masaki Fujimoto, Toshio Terasawa
Planetary and Space Science 93-94 87 - 95 2014.1
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Night side lunar surface potential in the Earth's magnetosphere Reviewed
Y. Saito, M. N. Nishino, S. Yokota, H. Tsunakawa, M. Matsushima, F. Takahashi, H. Shibuya, H. Shimizu
Advances in Space Research 54 ( 10 ) 1985 - 1992 2014.1
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Structure of the ionized lunar sodium and potassium exosphere: Dawn-dusk asymmetry Reviewed
Shoichiro Yokota, Takaaki Tanaka, Yoshifumi Saito, Kazushi Asamura, Masaki N. Nishino, Masaki Fujimoto, Hideo Tsunakawa, Hidetoshi Shibuya, Masaki Matsushima, Hisayoshi Shimizu, Futoshi Takahashi
Journal of Geophysical Research E: Planets 119 ( 4 ) 798 - 809 2014.1
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Small-scale magnetic fields on the lunar surface inferred from plasma sheet electrons Reviewed
Yuki Harada, Shinobu Machida, Yoshifumi Saito, Shoichiro Yokota, Kazushi Asamura, Masaki N. Nishino, Hideo Tsunakawa, Hidetoshi Shibuya, Futoshi Takahashi, Masaki Matsushima, Hisayoshi Shimizu
Geophysical Research Letters 40 ( 13 ) 3362 - 3366 2013.7
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Rapid changes in the electrical state of the 1999 Izmit earthquake rupture zone Reviewed
Honkura, Yoshimori, Oshiman, Naoto, Matsushima, Masaki, Baris, Serif, Tuncer, Mustafa Kemal, Tank, Sabri Bulent, Celik, Cengiz, Ciftci, Elif Tolak
NATURE COMMUNICATIONS 4 2013.7
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Circularly polarized electric fields associated with seismic waves generated by blasting Reviewed
Matsushima, Masaki, Honkura, Yoshimori, Kuriki, Mayu, Ogawa, Yasuo
GEOPHYSICAL JOURNAL INTERNATIONAL 194 ( 1 ) 200 - 211 2013.7
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Electrical characterization of the North Anatolian Fault Zone underneath the Marmara Sea, Turkey by ocean bottom magnetotellurics Reviewed
Kaya, Tuelay, Kasaya, Takafumi, Tank, S. Buelent, Ogawa, Yasuo, Tuncer, M. Kemal, Oshiman, Naoto, Honkura, Yoshimori, Matsushima, Masaki
GEOPHYSICAL JOURNAL INTERNATIONAL 193 ( 2 ) 664 - 677 2013.5
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Masaki N. Nishino, Masaki N. Nishino, Masaki N. Nishino, Masaki Fujimoto, Yoshifumi Saito, Hideo Tsunakawa, Yoshiya Kasahara, Mariko Kawamura, Mariko Kawamura, Masaki Matsushima, Futoshi Takahashi, Hidetoshi Shibuya, Hisayoshi Shimizu, Yoshitaka Goto, Kozo Hashimoto, Yoshiharu Omura, Atsushi Kumamoto, Takayuki Ono, Shoichiro Yokota
Planetary and Space Science 87 106 - 114 2013.1
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Constraint on the lunar core size from electromagnetic sounding based on magnetic field observations by an orbiting satellite Reviewed
Shimizu Hisayoshi, Matsushima Masaki, Takahashi Futoshi, Shibuya Hidetoshi, Tsunakawa Hideo
ICARUS 222 ( 1 ) 32 - 43 2013.1
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Kuriki, Mayu, Matsushima, Masaki, Ogawa, Yasuo, Honkura, Yoshimori
EARTH PLANETS AND SPACE 65 ( 1 ) 57 - 57 2013
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Control of lunar external magnetic enhancements by IMF polarity: A case study Reviewed
Masaki N. Nishino, Masaki Fujimoto, Hideo Tsunakawa, Masaki Matsushima, Hidetoshi Shibuya, Hisayoshi Shimizu, Futoshi Takahashi, Yoshifumi Saito, Shoichiro Yokota
Planetary and Space Science 73 ( 1 ) 161 - 167 2012.12
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Statistical study of broadband whistler-mode waves detected by Kaguya near the Moon Reviewed
Y. Tsugawa, Y. Katoh, N. Terada, T. Ono, H. Tsunakawa, F. Takahashi, H. Shibuya, H. Shimizu, M. Matsushima, Y. Saito, S. Yokota, M. N. Nishino
Geophysical Research Letters 39 2012.8
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Saito Yoshifumi, Nishino Masaki N, Fujimoto Masaki, Yamamoto Tadateru, Yokota Shoichiro, Tsunakawa Hideo, Shibuya Hidetoshi, Matsushima Masaki, Shimizu Hisayoshi, Takahashi Futoshi
EARTH PLANETS AND SPACE 64 ( 2 ) 83 - 92 2012.2
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Yoshifumi Saito, Masaki N. Nishino, Masaki Fujimoto, Tadateru Yamamoto, Shoichiro Yokota, Hideo Tsunakawa, Hidetoshi Shibuya, Masaki Matsushima, Hisayoshi Shimizu, Futoshi Takahashi
Earth, Planets and Space 64 ( 2 ) 83 - 92 2012.1
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Nongyrotropic electron velocity distribution functions near the lunar surface Reviewed
Yuki Harada, Shinobu Machida, Yoshifumi Saito, Shoichiro Yokota, Kazushi Asamura, Masaki N. Nishino, Hideo Tsunakawa, Hidetoshi Shibuya, Futoshi Takahashi, Masaki Matsushima, Hisayoshi Shimizu
Journal of Geophysical Research: Space Physics 117 2012.1
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かぐや衛星によって月周辺で観測される100秒周期磁場変動の発生機構
中山研仁, 中川朋子, 綱川秀夫, 松島政貴, 高橋 太, 渋谷秀敏, 清水久芳
東北工業大学紀要：理工学編 31 21 - 27 2011.12
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Statistical analysis of monochromatic whistler waves near the Moon detected by Kaguya Reviewed
Tsugawa, Y, Terada, N, Katoh, Y, Ono, T, Tsunakawa, H, Takahashi, F, Shibuya, H, Shimizu, H, Matsushima, M
Annales Geophysicae 29 1 - 5 2011.5
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Masaki N. Nishino, Xiao Dong Wang, Masaki Fujimoto, Hideo Tsunakawa, Yoshifumi Saito, Shoichiro Yokota, Wei Bian, Chun Lai Li, Masaki Matsushima, Hidetoshi Shibuya, Hisayoshi Shimizu, Futoshi Takahashi, Toshio Terasawa
Planetary and Space Science 59 ( 5-6 ) 378 - 386 2011.4
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Large-amplitude monochromatic ULF waves detected by Kaguya at the moon Reviewed
Nishino, M. N, Wang, X.-D, Fujimoto, M, Tsunakawa, H, Saito, Y, Yokota, S, Bian, W, Li, C.-L, Matsushima, M, Shibuya, H, Shimizu, H, Takahashi, F, Terasawa, T
Journal of Geophysical Research 117 A04101-13 2011.4
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Non-monochromatic whistler waves detected by Kaguya on the dayside surface of the moon Reviewed
Tomoko Nakagawa, Futoshi Takahashi, Hideo Tsunakawa, Hidetoshi Shibuya, Hisayoshi Shimizu, Masaki Matsushima
Earth, Planets and Space 63 ( 1 ) 37 - 46 2011.1
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Yoshifumi Saito, Masaki N. Nishino, Shoichiro Yokota, Takaaki Tanaka, Tadateru Yamamoto, Kazushi Asamura, Hideo Tsunakawa, Hidetoshi Shibuya, Hisayoshi Shimizu, Futoshi Takahashi, Masaki Matsushima
The Dynamic Magnetosphere 359 - 366 2011
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Spectral peaks in electric field at resonance frequencies for seismically excited motion of ions in the Earth's magnetic field Reviewed
Kuriki, Mayu, Matsushima, Masaki, Ogawa, Yasuo, Honkura, Yoshimori
EARTH PLANETS AND SPACE 63 ( 6 ) 503 - 507 2011
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Generation mechanism of the 100-second magnetic field variations observed by Kaguya around the Moon
A. Nakayama, T. Nakagawa, H. Tsunakawa, M. Matsushima, F. Takahashi, H. Shibuya, H. Shimizu
Memoirs of the Tohoku Institute of Technology. Ser.1, Science and engineering 31 ( 31 ) 21 - 27 2011
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Yuki Harada, Shinobu MacHida, Yoshifumi Saito, Shoichiro Yokota, Kazushi Asamura, Masaki N. Nishino, Takaaki Tanaka, Hideo Tsunakawa, Hidetoshi Shibuya, Futoshi Takahashi, Masaki Matsushima, Hisayoshi Shimizu
Geophysical Research Letters 37 2010.10
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K. Hashimoto, M. Hashitani, Y. Kasahara, Y. Omura, M. N. Nishino, Y. Saito, S. Yokota, T. Ono, H. Tsunakawa, H. Shibuya, M. Matsushima, H. Shimizu, F. Takahashi
Geophysical Research Letters 37 2010.10
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Yoshifumi Saito, Shoichiro Yokota, Kazushi Asamura, Takaaki Tanaka, Masaki N. Nishino, Tadateru Yamamoto, Yuta Terakawa, Masaki Fujimoto, Hiroshi Hasegawa, Hajime Hayakawa, Masafumi Hirahara, Masahiro Hoshino, Shinobu MacHida, Toshifumi Mukai, Tsugunobu Nagai, Tsutomu Nagatsuma, Tomoko Nakagawa, Masato Nakamura, Koh Ichiro Oyama, Eiichi Sagawa, Susumu Sasaki, Kanako Seki, Iku Shinohara, Toshio Terasawa, Hideo Tsunakawa, Hidetoshi Shibuya, Masaki Matsushima, Hisayoshi Shimizu, Futoshi Takahashi
Space Science Reviews 154 ( 1-4 ) 265 - 303 2010.7
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Magnetic Cleanliness Program Under Control of Electromagnetic Compatibility for the SELENE (Kaguya) Spacecraft Reviewed
Matsushima Masaki, Tsunakawa Hideo, Iijima Yu-ichi, Nakazawa Satoru, Matsuoka Ayako, Ikegami Shingo, Ishikawa Tomoaki, Shibuya Hidetoshi, Shimizu Hisayoshi, Takahashi Futoshi
SPACE SCIENCE REVIEWS 154 ( 1-4 ) 253 - 264 2010.7
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Lunar Magnetic Field Observation and Initial Global Mapping of Lunar Magnetic Anomalies by MAP-LMAG Onboard SELENE (Kaguya) Reviewed
Tsunakawa Hideo, Shibuya Hidetoshi, Takahashi Futoshi, Shimizu Hisayoshi, Matsushima Masaki, Matsuoka Ayako, Nakazawa Satoru, Otake Hisashi, Iijima Yuichi
SPACE SCIENCE REVIEWS 154 ( 1-4 ) 219 - 251 2010.7
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Effect of the solar wind proton entry into the deepest lunar wake Reviewed
M. N. Nishino, M. Fujimoto, Y. Saito, S. Yokota, Y. Kasahara, Y. Omura, Y. Goto, K. Hashimoto, A. Kumamoto, T. Ono, H. Tsunakawa, M. Matsushima, F. Takahashi, H. Shibuya, H. Shimizu, T. Terasawa
Geophysical Research Letters 37 2010.6
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A model for observed circular polarized electric fields coincident with the passage of large seismic waves Reviewed
Y. Honkura, Y. Ogawa, M. Matsushima, S. Nagaoka, N. Ujihara, T. Yamawaki
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH 114 2009.10
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Two mechanisms of solar-wind proton entry deep into the near-Moon wake revealed by SELENE (Kaguya)
Nishino, M. N, Fujimoto, M, Maezawa, K, Saito, Y, Yokota, S, Asamura, K, Tanaka, T, Tsunakawa, H, Shibuya, H, Matsushima, M, Shimizu, H, Takahashi, F, Terasawa, T
Proc. 42nd ISAS Lunar Planet. Symp. 1 - 4 2009.8
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Erratum to "A numerical dynamo benchmark" [Phys. Earth Planet. Int. 128 (1-4) (2001) 25-34] (DOI:10.1016/S0031-9201(01)00275-8) Reviewed
U. R. Christensen, J. Aubert, P. Cardin, E. Dormy, S. Gibbons, G. A. Glatzmaier, E. Grote, Y. Honkura, C. Jones, M. Kono, M. Matsushima, A. Sakuraba, F. Takahashi, A. Tilgner, J. Wicht, K. Zhang
Physics of the Earth and Planetary Interiors 172 ( 3-4 ) 356 2009.2
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月面における電磁場観測
松島 政貴, 清水 久芳, 綱川 秀夫, 渋谷 秀敏, 高橋 太, 松岡 彩子, 藤 浩明, 吉村 令慧, 小田 啓邦, 飯島 祐一, 小川 和律, 田中智
CA論文集 115 - 119 2009
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Plasma Measurement in the Lunar Wake by Kaguya MAP Reviewed
17 ( 3 ) 2008.9
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Pictorial 3 : Magnetic Lines of Force outside the Earth's Core
MATSUSHIMA Masaki
J. Geogr. 114 ( 2 ) Plate4a - Plate4a 2005
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Wide-band MT observations over Kusatsu-Shirane Volcano (1)
Ogawa Y., S. Bulent Tank, Honkura Y., Mastushima M., Hirabayashi J., Ohwada M., Nakamura K., Suzuki T., Katabuchi Y., Saito A., Mizuhashi M.
PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN 2001 138 - 138 2001
MISC
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An event study on broadband electric field noises and electron distributions in the lunar wake boundary
Masaki N. Nishino, Yoshiya Kasahara, Yuki Harada, Yoshifumi Saito, Hideo Tsunakawa, Atsushi Kumamoto, Shoichiro Yokota, Futoshi Takahashi, Masaki Matsushima, Hidetoshi Shibuya, Hisayoshi Shimizu, Yukinaga Miyashita, Yoshitaka Goto, Takayuki Ono
Earth, Planets and Space 74 ( 1 ) 2022.12
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月地殻磁場によるプラズマシート電子の非断熱的な散乱
原田裕己, 町田忍, 齋藤義文, 横田勝一郎, 浅村和史, 西野真木, 綱川秀夫, 渋谷秀敏, 高橋太, 松島政貴, 清水久芳
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 2012
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月磁気異常帯が電子gyro-loss効果に与える影響
原田裕己, 町田忍, 齋藤義文, 横田勝一郎, 浅村和史, 西野真木, 綱川秀夫, 渋谷秀敏, 高橋太, 松島政貴, 清水久芳
地球電磁気・地球惑星圏学会総会及び講演会予稿集(CD-ROM) 130th 2011
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Magnetic field investigation of Mercury's magnetosphere and the inner heliosphere by MMO/MGF
Wolfgang Baumjohann, Ayako Matsuoka, Werner Magnes, Karl-Heinz Glassmeier, Rumi Nakamura, Helfried Biernat, Magda Delva, Konrad Schwingenschuh, Tielong Zhang, Hans-Ulrich Auster, Karl-Heinz Fornacon, Ingo Richter, Andre Balogh, Peter Cargill, Chris Carr, Michele Dougherty, Timothy S. Horbury, Elizabeth A. Lucek, Fumio Tohyama, Takao Takahashi, Makoto Tanaka, Tsugunobu Nagai, Hideo Tsunakawa, Masaki Matsushima, Hideaki Kawano, Akimasa Yoshikawa, Hidetoshi Shibuya, Tomoko Nakagawa, Masahiro Hoshino, Yoshimasa Tanaka, Ryuho Kataoka, Brian J. Anderson, Christopher T. Russell, Uwe Motschmann, Manabu Shinohara
PLANETARY AND SPACE SCIENCE 58 ( 1-2 ) 279 - 286 2010.1
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The fluxgate magnetometer of the BepiColombo Mercury Planetary Orbiter
K. -H. Glassmeier, H. -U. Auster, D. Heyner, K. Okrafka, C. Carr, G. Berghofer, B. J. Anderson, A. Balogh, W. Baumjohann, P. Cargill, U. Christensen, M. Delva, M. Dougherty, K. -H. Fornacon, T. S. Horbury, E. A. Lucek, W. Magnes, M. Mandea, A. Matsuoka, M. Matsushima, U. Motschmann, R. Nakamura, Y. Narita, H. O'Brien, I. Richter, K. Schwingenschuh, H. Shibuya, J. A. Slavin, C. Sotin, B. Stoll, H. Tsunakawa, S. Vennerstrom, J. Vogt, T. Zhang
PLANETARY AND SPACE SCIENCE 58 ( 1-2 ) 287 - 299 2010.1
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Spatial variation of the stress field along the fault rupture zone of the 1999 Izmit earthquake
A. Pinar, S. B. Ucer, Y. Honkura, N. Sezgin, A. Ito, S. Baris, D. Kalafat, M. Matsushima, S. Horiuchi
EARTH PLANETS AND SPACE 62 ( 3 ) 237 - 256 2010
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Spatial variation of the stress field along the fault rupture zone of the 1999 Izmit earthquake
A. Pinar, S. B. Ucer, Y. Honkura, N. Sezgin, A. Ito, S. Baris, D. Kalafat, M. Matsushima, S. Horiuchi
EARTH PLANETS AND SPACE 62 ( 3 ) 237 - 256 2010
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かぐや衛星によって観測された電子速度分布関数における“gyro-loss”効果
原田裕己, 町田忍, 齋藤義文, 横田勝一郎, 浅村和史, 西野真木, 綱川秀夫, 渋谷秀敏, 高橋太, 松島政貴, 清水久芳
地球電磁気・地球惑星圏学会総会及び講演会予稿集(CD-ROM) 128th 2010
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「かぐや」が観測した月-月周辺プラズマの観測結果を中心に-
齋藤義文, 横田勝一郎, 田中孝明, 浅村和史, 西野真木, 山本忠輝, 綱川秀夫, 渋谷秀敏, 清水久芳, 高橋太, 松島政貴
宇宙航空研究開発機構研究開発報告 JAXA-RR- ( 09-003 ) 2010
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First in situ observation of the Moon-originating ions in the Earth's Magnetosphere by MAP-PACE on SELENE (KAGUYA)
Takaaki Tanaka, Yoshifumi Saito, Shoichiro Yokota, Kazushi Asamura, Masaki N. Nishino, Hideo Tsunakawa, Hidetoshi Shibuya, Masaki Matsushima, Hisayoshi Shimizu, Futoshi Takahashi, Masaki Fujimoto, Toshifumi Mukai, Toshio Terasawa
GEOPHYSICAL RESEARCH LETTERS 36 ( 22 ) L22106 2009.11
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Solar-wind proton access deep into the near-Moon wake
M. N. Nishino, M. Fujimoto, K. Maezawa, Y. Saito, S. Yokota, K. Asamura, T. Tanaka, H. Tsunakawa, M. Matsushima, F. Takahashi, T. Terasawa, H. Shibuya, H. Shimizu
GEOPHYSICAL RESEARCH LETTERS 36 ( 16 ) L16103 2009.8
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Pairwise energy gain-loss feature of solar wind protons in the near-Moon wake
M. N. Nishino, K. Maezawa, M. Fujimoto, Y. Saito, S. Yokota, K. Asamura, T. Tanaka, H. Tsunakawa, M. Matsushima, F. Takahashi, T. Terasawa, H. Shibuya, H. Shimizu
GEOPHYSICAL RESEARCH LETTERS 36 ( 12 ) L12108-L12108-5 2009.6
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First direct detection of ions originating from the Moon by MAP-PACE IMA onboard SELENE (KAGUYA)
Shoichiro Yokota, Yoshifumi Saito, Kazushi Asamura, Takaaki Tanaka, Masaki N. Nishino, Hideo Tsunakawa, Hidetoshi Shibuya, Masaki Matsushima, Hisayoshi Shimizu, Futoshi Takahashi, Masaki Fujimoto, Toshifumi Mukai, Toshio Terasawa
GEOPHYSICAL RESEARCH LETTERS 36 ( 11 ) L11201-L11201-4 2009.6
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A numerical dynamo benchmark (vol 128, pg 25, 2001)
U. R. Christensen, J. Aubert, P. Cardin, E. Dormy, S. Gibbons, G. A. Glatzmaier, E. Grote, Y. Honkura, C. Jones, M. Kono, M. Matsushima, A. Sakuraba, F. Takahashi, A. Tilgner, J. Wicht, K. Zhang
PHYSICS OF THE EARTH AND PLANETARY INTERIORS 172 ( 3-4 ) 356 - 356 2009.2
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In-orbit calibration of the lunar magnetometer onboard SELENE (KAGUYA)
Futoshi Takahashi, Hisayoshi Shimizu, Masaki Matsushima, Hidetoshi Shibuya, Ayako Matsuoka, Satoru Nakazawa, Yuichi Iijima, Hisashi Otake, Hideo Tsunakawa
Earth, Planets and Space 61 ( 11 ) 1269 - 1274 2009
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In-orbit calibration of the lunar magnetometer onboard SELENE (KAGUYA)
Futoshi Takahashi, Hisayoshi Shimizu, Masaki Matsushima, Hidetoshi Shibuya, Ayako Matsuoka, Satoru Nakazawa, Yuichi Iijima, Hisashi Otake, Hideo Tsunakawa
EARTH PLANETS AND SPACE 61 ( 11 ) 1269 - 1274 2009
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A model for observed circular polarized electric fields coincident with the passage of large seismic waves
Honkura, Y, Y. Ogawa, M. Matsushima, S. Nagaoka, N. Ujihara, T. Yamawaki
J. Geophys. Res. 114 ( B10 ) B10103 2009
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A model for observed circular polarized electric fields coincident with the passage of large seismic waves
Honkura, Y, Y. Ogawa, M. Matsushima, S. Nagaoka, N. Ujihara, T. Yamawaki
J. Geophys. Res. 114 ( B10 ) B10103 2009
-
月面反射太陽風イオンの月磁気異常による加速
横田勝一郎, 斎藤義文, 浅村和史, 田中孝明, 西野真木, 山本忠輝, 綱川秀夫, 渋谷秀敏, 松島政貴, 清水久芳, 高橋太, 藤本正樹, 向井利典, 寺沢敏夫, 齋藤義文, 綱川秀夫
地球電磁気・地球惑星圏学会総会及び講演会予稿集(CD-ROM) 126th 2009
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Plasmoid formation for multiple onset substorms: observations of the Japanese Lunar Mission "Kaguya"
T. Nagai, H. Tsunakawa, H. Shibuya, F. Takahashi, H. Shimizu, M. Matsushima, M. N. Nishino, Y. Yokota, K. Asamura, T. Tanaka, Y. Saito, O. Amm
ANNALES GEOPHYSICAE 27 ( 1 ) 59 - 64 2009
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Solar wind proton reflection at the lunar surface: Low energy ion measurement by MAP-PACE onboard SELENE (KAGUYA)
Y. Saito, S. Yokota, T. Tanaka, K. Asamura, M. N. Nishino, M. Fujimoto, H. Tsunakawa, H. Shibuya, M. Matsushima, H. Shimizu, F. Takahashi, T. Mukai, T. Terasawa
GEOPHYSICAL RESEARCH LETTERS 35 ( 24 ) L24205 2008.12
-
Effects of thermally heterogeneous structure in the lowermost mantle on the geomagnetic field strength
F. Takahashi, H. Tsunakawa, M. Matsushima, N. Mochizuki, Y. Honkura
EARTH AND PLANETARY SCIENCE LETTERS 272 ( 3-4 ) 738 - 746 2008.8
-
Scale variability in convection-driven MHD dynamos at low Ekman number
Futoshi Takahashi, Masaki Matsushima, Yoshimori Honkura
Physics of the Earth and Planetary Interiors 167 ( 3-4 ) 168 - 178 2008.4
-
Scale variability in convection-driven MHD dynamos at low Ekman number
Futoshi Takahashi, Masaki Matsushima, Yoshimori Honkura
PHYSICS OF THE EARTH AND PLANETARY INTERIORS 167 ( 3-4 ) 168 - 178 2008.4
-
Equivalent source mapping of the lunar crustal magnetic field using ABIC
M. Toyoshima, H. Shibuya, M. Matsushima, H. Shimizu, H. Tsunakawa
EARTH PLANETS AND SPACE 60 ( 4 ) 365 - 373 2008
-
Ground calibration of the high-sensitivity SELENE lunar magnetometer LMAG
Hisayoshi Shimizu, Futoshi Takahashi, Naoki Horii, Ayako Matsuoka, Masaki Matsushima, Hidetoshi Shibuya, Hideo Tsunakawa
EARTH PLANETS AND SPACE 60 ( 4 ) 353 - 363 2008
-
The origin of Mercury's internal magnetic field
J. Wicht, M. Mandea, F. Takahashi, U. R. Christensen, M. Matsushima, B. Langlais
SPACE SCIENCE REVIEWS 132 ( 2-4 ) 261 - 290 2007.10
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Source mechanism of the 2000 November 15 Lake Van earthquake (M-w=5.6) in eastern Turkey and its seismotectonic implications
A. Pinar, Y. Honkura, K. Kuge, M. Matsushima, N. Sezgin, M. Yilmazer, Z. Oeguetcu
GEOPHYSICAL JOURNAL INTERNATIONAL 170 ( 2 ) 749 - 763 2007.8
-
A numerical study on magnetic polarity transition in an MHD dynamo model
Futoshi Takahashi, Masaki Matsushima, Yoshimori Honkura
Earth, Planets and Space 59 ( 7 ) 665 - 673 2007
-
A numerical study on magnetic polarity transition in an MHD dynamo model
Futoshi Takahashi, Masaki Matsushima, Yoshimori Honkura
EARTH PLANETS AND SPACE 59 ( 7 ) 665 - 673 2007
-
443 Large Data Visualization for Numerical Simulation of Geomagnetic Field Variations Dynamos
KATO Shigeru, MATSUSHIMA Masaki, TAKAHASHI Futoshi, OGAWA Satoi, AOKI Takayuki
The Computational Mechanics Conference 2006 ( 19 ) 715 - 716 2006.11
-
Reexamination of a scale-similarity model for the subgrid-scale flux in the Earth's core
Masaki Matsushima
Geophysical and Astrophysical Fluid Dynamics 100 ( 4-5 ) 363 - 377 2006.8
-
Reexamination of a scale-similarity model for the subgrid-scale flux in the Earth's core
Masaki Matsushima
GEOPHYSICAL AND ASTROPHYSICAL FLUID DYNAMICS 100 ( 4-5 ) 363 - 377 2006.8
-
Dipolar and non-dipolar dynamos in a thin shell geometry with implications for the magnetic field of Mercury
Futoshi Takahashi, Masaki Matsushima
Geophysical Research Letters 33 ( 10 ) L10202 - L10202 2006.5
-
Dipolar and non-dipolar dynamos in a thin shell geometry with implications for the magnetic field of Mercury
F Takahashi, M Matsushima
GEOPHYSICAL RESEARCH LETTERS 33 ( 10 ) L10202 - L10202 2006.5
-
Mini-magnetosphere over the Reiner Gamma magnetic anomaly region on the Moon
M Kurata, H Tsunakawa, Y Saito, H Shibuya, M Matsushima, H Shimizu
GEOPHYSICAL RESEARCH LETTERS 32 ( 24 ) L24205-L24205-4 - L24205 2005.12
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A scale-similarity model for the subgrid-scale flux with application to MHD turbulence in the Earth's core
Masaki Matsushima
Physics of the Earth and Planetary Interiors 153 ( 1-3 ) 74 - 82 2005.11
-
A scale-similarity model for the subgrid-scale flux with application to MHD turbulence in the Earth's core
M Matsushima
PHYSICS OF THE EARTH AND PLANETARY INTERIORS 153 ( 1-3 ) 74 - 82 2005.11
-
Geophysics: Simulations of a quasi-Taylor state geomagnetic field including polarity reversals on the Earth simulator
Futoshi Takahashi, Masaki Matsushima, Yoshimori Honkura
Science 309 ( 5733 ) 459 - 461 2005.7
-
Simulations of a quasi-Taylor state geomagnetic field including polarity reversals on the Earth Simulator
F Takahashi, M Matsushima, Y Honkura
SCIENCE 309 ( 5733 ) 459 - 461 2005.7
-
Dynamo action in a rotating spherical shell at high Rayleigh numbers
F Takahashi, M Matsushima
PHYSICS OF FLUIDS 17 ( 7 ) 076601 2005.7
-
Magnetotelluric imaging of the fault rupture area of the 1999 Izmit (Turkey) earthquake
SB Tank, Y Honkura, Y Ogawa, M Matsushima, N Oshiman, MK Tuncer, C Celik, E Tolak, AM Isikara
PHYSICS OF THE EARTH AND PLANETARY INTERIORS 150 ( 1-3 ) 213 - 225 2005.5
-
Fluid motion in the core estimated from the Earth's magnetic field
Masaki Matsushima
Journal of Geography 114 ( 2 ) 132 - 141 2005
-
Fluid Motion in the Core Estimated from the Earth's Magnetic Field
MATSUSHIMA Masaki
J. Geogr. 114 ( 2 ) 132 - 141 2005
-
Scale similarity of MHD turbulence in the Earth's core
M Matsushima
EARTH PLANETS AND SPACE 56 ( 6 ) 599 - 605 2004
-
Scale similarity of MHD turbulence in the Earth's core
Matsushima, M
Earth, Planets and Space 56 ( 6 ) 599 - 605 2004
-
Dynamo action and its temporal variation inside the tangent cylinder in MHD dynamo simulations
F Takahashi, A Matsushima, Y Honkura
PHYSICS OF THE EARTH AND PLANETARY INTERIORS 140 ( 1-3 ) 53 - 71 2003.11
-
Resistivity structure in the western part of the fault rupture zone associated with the 1999 Izmit earthquake and its seismogenic implication
SB Tank, Y Honkura, Y Ogawa, N Oshiman, MK Tuncer, M Matsushima, C Celik, E Tolak, AM Isikara
EARTH PLANETS AND SPACE 55 ( 7 ) 437 - 442 2003
-
Seismoelectromagnetic effect associated with the Izmit earthquake and its aftershocks
M Matsushima, Y Honkura, N Oshiman, S Baris, MK Tuncer, SB Tank, C Celik, F Takahashi, M Nakanishi, R Yoshimura, R Pektas, T Komut, E Tolak, A Ito, Y Lio, AM Isikara
BULLETIN OF THE SEISMOLOGICAL SOCIETY OF AMERICA 92 ( 1 ) 350 - 360 2002.2
-
Deep resistivity structure around the fault associated with the 1999 Kocaeli earthquake, Turkey
Oshiman, N, R. Yoshimura, T. Kasaya, YOSHIMORI HONKURA, M. Matsushima, S. Baris, C. Celik, M. K. Tuncer, A. M. Isikara
Seismotectonics in Convergent Plate Boundary 293 - 303 2002
-
Small electric and magnetic signals observed before the arrival of seismic wave
Y Honkura, M Matsushima, N Oshiman, MK Tuncer, S Baris, A Ito, Y Iio, AM Isikara
EARTH PLANETS AND SPACE 54 ( 12 ) E9 - E12 2002
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Deep resistivity structure around the fault associated with the 1999 Kocaeli earthquake, Turkey
Oshiman, N, R. Yoshimura, T. Kasaya, YOSHIMORI HONKURA, M. Matsushima, S. Baris, C. Celik, M. K. Tuncer, A. M. Isikara
Seismotectonics in Convergent Plate Boundary 293 - 303 2002
-
A numerical dynamo benchmark
UR Christensen, J Aubert, P Cardin, E Dormy, S Gibbons, GA Glatzmaier, E Grote, Y Honkura, C Jones, M Kono, M Matsushima, A Sakuraba, F Takahashi, A Tilgner, J Wicht, K Zhang
PHYSICS OF THE EARTH AND PLANETARY INTERIORS 128 ( 1-4 ) 25 - 34 2001.12
-
Effects of boundary layers on magnetic field behavior in an MHD dynamo model
F Takahashi, JS Katayama, M Matsushima, Y Honkura
PHYSICS OF THE EARTH AND PLANETARY INTERIORS 128 ( 1-4 ) 149 - 161 2001.12
-
Expression of turbulent heat flux in the Earth's core in terms of a second moment closure model
M Matsushima
PHYSICS OF THE EARTH AND PLANETARY INTERIORS 128 ( 1-4 ) 137 - 148 2001.12
-
Magnetotelluric imaging of fluids in intraplate earthquake zones, NE Japan back arc
Y Ogawa, M Mishina, T Goto, H Satoh, N Oshiman, T Kasaya, Y Takahashi, T Nishitani, S Sakanaka, M Uyeshima, Y Takahashi, Y Honkura, M Matsushima
GEOPHYSICAL RESEARCH LETTERS 28 ( 19 ) 3741 - 3744 2001.10
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磁場でみる地球惑星深部構造
松島政貴
日本AEM学会誌 9 443 - 449 2001
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Expression of turbulent heat flux in the Earth's core in terms of a second moment closure model
Masaki Matsushima
Physics of the Earth and Planetary Interiors 128 ( 1-4 ) 137 - 148 2001
-
Preliminary results of multidisciplinary observations before, during and after the Kocaeli (Izmit) earthquake in the western part of the North Anatolian Fault Zone
Y Honkura, AM Isikara, N Oshiman, A Ito, B Ucer, S Baris, MK Tuncer, M Matsushima, R Pektas, C Celik, SB Tank, F Takahashi, M Nakanishi, R Yoshimura, Y Ikeda, T Komut
EARTH PLANETS AND SPACE 52 ( 4 ) 293 - 298 2000
-
Resistivity structure of the fault associated with the 1999 Kocaeli earthquake
OSHIMAN N., YOSHIMURA R., HONKURA Y., MATSUSHIMA M., TAKAHASHI F., NAKANISHI M., ISIKARA A.M., BARIS S., TUNCER M.K.
1999 ( 2 ) A65 1999.11
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Electromagnetic Response Associated with the Kocaeli Earthquake, Turkey, 1999
MATSUSHIMA M., HONKURA Y., TAKAHASHI F., NAKANISHI M., OSHIMAN N., YOSHIMURA R., ISIKARA A.M., BARIS S., TUNCER M.K., TANK S.B., CELIK C., IIO Y., ITO A.
1999 ( 2 ) P131 1999.11
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Some characteristics of magnetic field behavior in a model of MHD dynamo thermally driven in a rotating spherical shell
J. S. Katayama, M. Matsushima, Y. Honkura
Physics of the Earth and Planetary Interiors 111 ( 1-2 ) 141 - 159 1999.2
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Some characteristics of magnetic field behavior in a model of MHD dynamo thermally driven in a rotating spherical shell
JS Katayama, M Matsushima, Y Honkura
PHYSICS OF THE EARTH AND PLANETARY INTERIORS 111 ( 1-2 ) 141 - 159 1999.2
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The anisotropy of local turbulence in the Earth's core
M Matsushima, T Nakajima, PH Roberts
EARTH PLANETS AND SPACE 51 ( 4 ) 277 - 286 1999
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Electromagnetic response of the mantle to long-period geomagnetic variations over the globe
Y. Honkura, M. Matsushima
Earth, Planets and Space 50 ( 8 ) 651 - 662 1998
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Electromagnetic response of the mantle to long-period geomagnetic variations over the globe
Y Honkura, M Matsushima
EARTH PLANETS AND SPACE 50 ( 8 ) 651 - 662 1998
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MHD Dynamo Simulation
Chikyu Monthly ( 号外17 ) 61 - 65 1997
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MHDダイナモシミュレーション (総特集 地球の活動と電磁気現象--行武毅教授退官記念号) -- (3章 地球磁場の成因と永年変化)
佐藤 淳子, 松島 政貴, 本蔵 義守
号外地球 ( 17 ) 61 - 65 1997
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MHDダイナモシミュレーション
佐藤淳子, 松島政貴, 本蔵義守
月刊地球 ( 号外17 ) 61 - 65 1997
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Variations of the electric potential in the vicinity of the Nojima Fault during the activity of aftershocks of the 1995 Hyogo-ken Nanbu earthquake
Y. Honkura, H. Tsunakawa, M. Matsushima
Journal of Physics of the Earth 44 ( 4 ) 397 - 403 1996
-
MT Survey in the Nikko Area
Proceedings of CA Workshop 1996 121 - 127 1996
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Behaviour of the electric potential during the activity of aftershocks of the M7.2 earthquake, Japan with special reference to SES of VAN
Y. Honkura, H. Tsunakawa, M. Matsushima
A Critical Review of VAN 303 - 313 1996
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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
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Behaviour of the electric potential during the activity of aftershocks of the M7.2 earthquake, Japan with special reference to SES of VAN
Y. Honkura, H. Tsunakawa, M. Matsushima
A Critical Review of VAN 303 - 313 1996
-
VELOCITY AND MAGNETIC-FIELDS IN THE EARTHS CORE ESTIMATED FROM THE GEOMAGNETIC-FIELD
M MATSUSHIMA
PHYSICS OF THE EARTH AND PLANETARY INTERIORS 91 ( 1-3 ) 99 - 115 1995.9
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MAGNETIZATION STRUCTURE OF THE UNZEN VOLCANO DETERMINED FROM BLIMP-BORNE MAGNETIC SURVEY DATA Reviewed
Y HONKURA, M MATSUSHIMA, N OSHIMAN, Y SASAI, M OHNO, Y TANAKA, T YAMAMOTO, K IKEDA, Y WAKINO
JOURNAL OF GEOMAGNETISM AND GEOELECTRICITY 47 ( 2 ) 231 - 236 1995
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On truncation levels in spherical harmonic expension of magnetic and velocity fields in an MHD dynamo model
Y. Tanahashi, Y. Honkura, M. Matsushima
The Earth's Central Part: Its Structure and Dynamics 105 - 122 1995
-
地球核内の流体運動と磁場
松島政貴, 本蔵義守
シミュレーション 14 ( 4 ) 271 - 278 1995
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Strength of the magnetic field in the Earth's core estimated from geomagnetic field data
MASAKI MATSUSHIMA
The Earth's Central Part: Its Structure and Dynamics 95 - 104 1995
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Velocity and magnetic fields in the Earth's core estimated from the geomagnetic field
Masaki Matsushima
Physics of the Earth and Planetary Interiors 91 ( 1-3 ) 99 - 115 1995
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Fluid Motion and Magnetic Field in the Earth's Core
Journal of the Japan Society for Simulation Technology 14 ( 4 ) 271 - 278 1995
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On truncation levels in spherical harmonic expension of magnetic and velocity fields in an MHD dynamo model
Y. Tanahashi, Y. Honkura, M. Matsushima
The Earth's Central Part: Its Structure and Dynamics 105 - 122 1995
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Strength of the magnetic field in the Earth's core estimated from geomagnetic field data
MASAKI MATSUSHIMA
The Earth's Central Part: Its Structure and Dynamics 95 - 104 1995
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FLUID MOTION IN THE EARTHS CORE DERIVED FROM THE GEOMAGNETIC-FIELD AND ITS IMPLICATIONS FOR THE GEODYNAMO
M MATSUSHIMA
JOURNAL OF GEOMAGNETISM AND GEOELECTRICITY 45 ( 11-12 ) 1481 - 1495 1993
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Fluid motion in the earth's core derived from the geomagnetic field and its implications for the geodynamo.
Masaki Matsushima
Journal of Geomagnetism and Geoelectricity 45 ( 11/12 ) 1481 - 1495 1993
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Polority reversals of the Earth's magnetic field in MHD dynamo models
Chikyu Monthly 15 ( 2 ) 92 - 95 1993
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MHDダイナモにおける磁場極性の逆転
本蔵義守, 飯島友邦, 松島政貴
月刊地球 15 ( 2 ) 92 - 95 1993
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EFFECTS OF AN INHOMOGENEOUS TEMPERATURE DISTRIBUTION AT THE CMB ON POLARITY REVERSALS OF THE EARTHS MAGNETIC-FIELD
Y HONKURA, T IIJIMA, M MATSUSHIMA, Y TANAHASHI
JOURNAL OF GEOMAGNETISM AND GEOELECTRICITY 45 ( 11-12 ) 1591 - 1604 1993
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REEXAMINATION OF FLUID MOTION IN THE EARTHS CORE DERIVED FROM GEOMAGNETIC-FIELD DATA - IS THE OMEGA-EFFECT REALLY STRONG IN THE CORE
M MATSUSHIMA, Y HONKURA
JOURNAL OF GEOMAGNETISM AND GEOELECTRICITY 44 ( 7 ) 521 - 553 1992
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MAGNETIC-FIELD REVERSAL RESULTING FROM A DYNAMO PROCESS IN A SPHERICAL-SHELL
Y HONKURA, T IIJIMA, M MATSUSHIMA
JOURNAL OF GEOMAGNETISM AND GEOELECTRICITY 44 ( 10 ) 931 - 941 1992
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核流体運動におけるマントルの役割
本蔵義守, 飯島友邦, 松島政貴
月刊地球 14 ( 6 ) 351 - 355 1992
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A role of the mantle in fluid motion in the core
Chikyu Monthly 14 ( 6 ) 351 - 355 1992
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REEXAMINATION OF FLUID MOTION IN THE EARTHS CORE DERIVED FROM GEOMAGNETIC-FIELD DATA - IS THE OMEGA-EFFECT REALLY STRONG IN THE CORE
M MATSUSHIMA, Y HONKURA
JOURNAL OF GEOMAGNETISM AND GEOELECTRICITY 44 ( 7 ) 521 - 553 1992
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Large-scale fluid motion in the Earth's outer core estimated from non-dipole magnetic field data
M. Matsushima, Y. Honkura
Journal of Geomagnetism and Geoelectricity 41 ( 11 ) 963 - 1000 1989
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地球磁場からみた外核の流体運動
松島政貴, 本蔵義守
号外地球 ( 2 ) 53 - 57 1989
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LARGE-SCALE FLUID MOTION IN THE EARTHS OUTER CORE ESTIMATED FROM NON-DIPOLE MAGNETIC-FIELD DATA
M MATSUSHIMA, Y HONKURA
JOURNAL OF GEOMAGNETISM AND GEOELECTRICITY 41 ( 11 ) 963 - 1000 1989
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Fluid motion in the outer core derived from geomagnetic field
Chikyu Extra ( 2 ) 53 - 57 1989
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FLUCTUATION OF THE NONDIPOLE MAGNETIC-FIELD AND ITS IMPLICATION FOR THE PROCESS OF GEOMAGNETIC POLARITY REVERSAL IN THE COX MODEL
Y HONKURA, M MATSUSHIMA
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH AND PLANETS 93 ( B10 ) 11631 - 11642 1988.10
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LOWER BOUND FOR THE ELECTRICAL-CONDUCTIVITY OF THE EARTHS OUTER CORE
Y HONKURA, M MATSUSHIMA
GEOPHYSICAL RESEARCH LETTERS 15 ( 7 ) 689 - 692 1988.7
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FLUCTUATION OF THE STANDING AND THE DRIFTING PARTS OF THE EARTHS MAGNETIC-FIELD
M MATSUSHIMA, Y HONKURA
GEOPHYSICAL JOURNAL-OXFORD 94 ( 1 ) 35 - 50 1988.7
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Fluctuation of the standing and drifting parts of the Earth's magnetic field
M. Matsushima, Y. Honkura
Geophysical Journal 94 ( 1 ) 35 - 50 1988
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Fluctuation of the nondipole magnetic field and its implication for the process of geomagnetic polatiry reversal in the Cox model
Y. Honkura, M. Matsushima
Journal of Geophysical Research 93 ( B10 ) 11631 - 11642 1988
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Time-dependent pattern of core motion inferred from fluctuations of standing and dritfing non-dipole fields
Y. Honkura, M. Matsushima
Journal of Geomagnetism and Geoelectricity 40 ( 12 ) 1511 - 1522 1988
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Lower bound for the electrical conductivity of the Earth's outer core
Y. Honkura, M. Matsushima
Geophysical Research Letters 15 ( 7 ) 689 - 692 1988
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TIME-DEPENDENT PATTERN OF CORE MOTION INFERRED FROM FLUCTUATIONS OF STANDING AND DRIFTING NON-DIPOLE FIELDS
Y HONKURA, M MATSUSHIMA
JOURNAL OF GEOMAGNETISM AND GEOELECTRICITY 40 ( 12 ) 1511 - 1522 1988
Presentations
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地球磁場変動ダイナモシミュレーションにおける大規模データの可視化
第19回計算力学講演会 2006
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Large Data Visualization for Numerical Simulation of Geomagnetic Field Variations Dynamos
The 19th Computational Mechanics Conference 2006
Works
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Structure of Active Faults in the North Anatolian Fault Zone
1999
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北アナトリア断層帯における活断層深部構造の研究
1999
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Forecast of Seismic Activity in the North Anatolian Fault
1995
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北アナトリア断層帯西部域地震活動予測に関する総合的研究
1995
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Multidisciplinary Research on Fault Activity in the Western Part of the North Anatolian Fault Zone
1988
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北アナトリア断層帯西部域における断層活動の調査
1988
Awards
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EPS Excellent Paper Award
2017 Earth, Planets and Space Simultaneous observation of the electron acceleration and ion deceleration over lunar magnetic anomalies, Earth Planets Space, 64:4, 2012
Yoshifumi Saito, Masaki N. Nishino, Masaki Fujimoto, Tadateru Yamamoto,Shoichiro Yokota, Hideo Tsunakawa, Hidetoshi Shibuya, Masaki Matsushima, Hisayoshi Shimizu, Futoshi Takahashi
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JGG論文奨励賞
1995
Research Projects
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地磁気データで明らかにする核－マントル結合の時空間変動
Grant number：16H01116 2016.4 - 2018.3
日本学術振興会 科学研究費助成事業 新学術領域研究(研究領域提案型)
松島 政貴
Grant amount：\4290000 （ Direct Cost: \3300000 、 Indirect Cost：\990000 ）
地磁気を生成・維持しているダイナモ作用は外核内の流れによって生じている。核－マントル境界における下降流および内核境界における上昇流の空間的組み合わせは外核内の流れのスケールやパターンを決める。流れのパターンは磁場生成過程に影響するので、地磁気の分布や永年変化にその影響が現れる。つまり、核－マントル結合の時空間変動の情報は、外核内の流れの時空間変動に含まれている。そして、外核内の流れの情報は地磁気データに含まれている。そこで、地磁気モデルを用いて外核内の流れを求める。そして、推定された外核内の流れの空間分布および時間変動から核－マントル結合の時空間変動を明らかにする。
Matsushima (2015) では、コア－マントル境界における粘性境界層下部の流れが地衡流であるという制約が課されていた。前年度、その手法を発展させることにより、つまり、流れが磁気地衡流であるという制約を課すことにより推定方法が改良されたことが確認された。しかしながら、コアの電気伝導度として以前から使われている値を採用した。近年の第一原理計算や室内実験に基づいたコアの電気伝導度の値は数倍から数十倍程度大きい。今年度は、コアの電気伝導度をパラメータとして、それがコアの流れを推定する際にどのように影響するかを調べた。コアの電気伝導度は誘導方程式の拡散項に含まれるので、磁場の動径方向についての２階微分の表現に寄与する。しかしながら、コア内部の磁場を計算するときのテイラー展開の２次の項に関連するだけであり、この点に関しては大きな影響がないことが確認された。一方、磁気地衡流制約の下ではローレンツ力の項が電気伝導度に比例する。そのため、電気伝導度が大きいほどコア内の流れのトロイダル成分が小さくなることがわかった。コア内の流れの推定にはより正確なコアの電気伝導度の値が必須である。 -
Seismic and geo-electromagnetic observations of core and mantle
Grant number：15H05832 2015.6 - 2020.3
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)
Tanaka Satoru
Grant amount：\178750000 （ Direct Cost: \137500000 、 Indirect Cost：\41250000 ）
We have constructed a mobile broadband seismic network that spans the whole of Thailand, and contributed to the elucidation of the fine structure of the lowermost mantle and the unexplored regions of the inner core. As a notable achievement, we integrated the data from the seismic network in Thailand with that from the existing networks in the surrounding areas, and clarified that the lowermost mantle beneath the western Pacific mantle, which was previously regarded as a large seismic low-velocity province, is a mixture of subducted plates and small-scale upwellings. Using data from the seismic network in Thailand, the uppermost inner core below the Arctic region was analyzed intensively for the first time, and it was clarified that the region belongs to the western hemisphere. In addition, we found that seismic velocity heterogeneity exists in the lowermost outer core and that the boundary of the hemispheric inner core has a transition zone with a width of about 600 km.
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Electromagnetic Imaging of Geofluid
Grant number：21109003 2009.7 - 2014.3
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)
OGAWA Yasuo, FUJITA Kiyoshi, KANDA Wataru, MATSUSHIMA Masaki, YOSHINO Takashi, TOH Hiroaki, UYESHIMA Makoto, ICHIKI Masahiro, KOYAMA Takao
Grant amount：\168220000 （ Direct Cost: \129400000 、 Indirect Cost：\38820000 ）
From the detailed magnetotelluric observations around the Naruko volcano in the central NE Japan arc, we analyzed three-dimensional resistivity structure of the crust and the upper mantle. We found sub-vertical conductors beneath active volcanoes, Naruko and Onikobe, which imply existence of saline fluid reservoir. In the upper mantle, we imaged a conductor on top of the down-going plate. The conductor extends towards the Moho under the backbone ranges. We also found that it also has a branch toward west beneath volcanoes along the Japan Sea. From the experimental resistivity measurements of a fluid bearing rocks under lower crustal conditions, we found that those crustal conductors, found by magnetotelluric measurements, need high salinity fluids.
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Structure and dynamics of the Earth's inner core boundary-The origin of hemispherical structure-
Grant number：21340132 2009 - 2012
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
TANAKA Satoru, MATSUSHIMA Masaki, SHIMIZU Hisayoshi
Grant amount：\18200000 （ Direct Cost: \14000000 、 Indirect Cost：\4200000 ）
Hemispherical difference of the inner core reaches at least 400km below the inner core boundary. Attenuation of seismic wave passing through the Eastern hemisphere can be explained by velocity perturbation within the uppermost 200km of the inner core. The reflected waves at the inner core boundary in the Eastern hemisphere show that 2Hz components are larger than those of 1Hz. The stability of morphology at the inner core surface depends on the growth rate of the inner core. Diffusivity affects kinetic and magnetic (in some case) energies of the outer core flow near the inner core boundary.
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Generation of electromagnetic field due to resonance between ground velocity and ions motion in the Earth's magnetic field
Grant number：21340126 2009 - 2011
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
MATSUSHIMA Masaki, HONKURA Yoshimori, OGAWA Yasuo
Grant amount：\17810000 （ Direct Cost: \13700000 、 Indirect Cost：\4110000 ）
Based on simultaneous observations of ground velocity and electromagnetic field, we have investigated the seismic dynamo effect, in which temporal variations of electromagnetic field associated with ground velocity are caused by cyclotron motion of ions contained in groundwater under the Earth's magnetic field. Circularly polarized electric field, detection of electric field earlier than arrival of seismic waves, and peak frequencies of the transfer function between ground velocity(input) and electric field(output) at cyclotron frequencies for ions in groundwater strongly support the seismic dynamo effect.
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Resistivity structures and fault activities of the seismic gap at the western part of the North Anatolian Fault
Grant number：19253002 2007 - 2009
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
OGAWA Yasuo, HONKURA Yoshimori, OSHIMAN Naoto, ITO Akihiko, MATSUSHIMA Masaki, KASAYA Takafumi
Grant amount：\43550000 （ Direct Cost: \33500000 、 Indirect Cost：\10050000 ）
We have analyzed 35 wide-band magnetotelluric data at Armutlu peninsula, where we had aftershock activity of 1999 Izmit earthquake, and found the earthquakes distribute outside of the crustal conductors. We also obtained 14 ocean-bottom magnetotelluric data in the Marmara Sea in the period range of 100-10,000 seconds. After preliminary 2d, 3d modeling, inhomogeneous resistivity structures are being revealed in relation to asperities.
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Understanding of a Mechanism of Geomagnetic Field Reversals by Highly Precise Numerical Simulations of the Geodynamo
Grant number：18340131 2006 - 2008
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
HONKURA Yoshimori, MATSUSHIMA Masaki
Grant amount：\15100000 （ Direct Cost: \13000000 、 Indirect Cost：\2100000 ）
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Modeling a mechanism of MHD turbulent diffusion in Earth and Planetary fluid cores
Grant number：15540405 2003 - 2005
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
MATSUSHIMA Masaki
Grant amount：\3700000 （ Direct Cost: \3700000 ）
Aiming at modeling an eddy diffusivity tensor, we have performed direct numerical simulations of MHD turbulence in a rapidly rotating system. To carry out computation using molecular diffusivity in a realistic planetary core, required is high resolution even for a very small region in the core. In the present research, the computational region is divided into several segments, which are allocated to respective CPUs on a parallel computer with large size of memory. Using results of direct numerical simulations thus obtained, we have examined scale similarity in MHD turbulence to model subgrid-scale physical processes, and we have found that scale similarity holds. On the basis of scale similarity law as well as spatial-filter width dependence, we have estimated the effect of subgrid-scales on grid-scales. We have then carried out large eddy simulations of MHD turbulence with the model of subgrid-scales. We have compared their results with those of direct numerical simulations, and confirmed that the present subgrid-scale model holds valid. That is, heat flux, kinetic energy, and magnetic energy averaged over computational time and computational region for large eddy simulation with the subgrid-scale model are closer to those for direct numerical simulations than those for numerical simulations without the model. It should be noted, however, that there is no significant difference among power spectra for velocity field, magnetic field, and temperature.
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STUDY OF THE EVALUATION OF EARTHQUAKE OCCURRENCE POTENTIAL IN THE WESTERN PART OF THE NORTH ANATOLIAN FAULT ZONE
Grant number：13373002 2001 - 2004
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
HONKURA Yoshimori, OGAWA Yasuo, OSHIMAN Naoto, ITO Akihiko, MATSUSHIMA Masaki
Grant amount：\53170000 （ Direct Cost: \40900000 、 Indirect Cost：\12270000 ）
In each year of this research project, we intensified seismic observations and advanced the analysis system, resulting in the establishment of an earthquake monitoring system in the Istanbul area, western Turkey. At present, seismic activity can be monitored on the web and also some data on major earthquakes are shown on the web, so that the data can be used for studies of earthquake generation mechanism. We have used the data for our own researches on seismic tomography and found that seismic activity becomes shallower in the earthquake source region of a big earthquake anticipated to the west of the Izmit earthquake source area. We also accumulated information on earthquake generation mechanism from waveform inversion for middle-size earthquakes, and increased our understanding of the distribution of crustal stress. As for seismicity itself, seismic activity is no very active in the earthquake source area for a big earthquake anticipated to the south of Istanbul, but it is rather active in its vicinity. Yearly data of hypocenters suggest an image of east-west active faults beneath the Marmara Sea and an image of the anticipated big earthquake has emerged. In electromagnetic studies, we made wide-band, long-period and short-period MT observations, and clarified the resistivity structure in a wide region including the Izmit earthquake source area. As a result, we found that earthquake source areas are resistive in general and highly resistive areas correspond to asperities. We also found a partial melting zone and its extension, as revealed by low resistivity zones widely existing in the lower crust and upper mantle. As for the seismic dynamo effect which we found during the Izmit earthquake, we made further studies for aftershocks associated with some major earthquakes, such as the Niigata Prefecture earthquake, which occurred recently in Japan. We could confirm the effect for earthquakes larger than magnitude 4.0, but could not detect electromagnetic signals anticipated theoretically before the arrival of seismic wave, simply because of low S/N for small earthquakes.
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Effects of anisotropic turbulent transport on generation mechanism of the Earth's magnetic field
Grant number：11640412 1999 - 2001
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
MATSUSHIMA Masaki
Grant amount：\1100000 （ Direct Cost: \1100000 ）
It is likely that large-scale fields are transported by small-scale motions in the Earth's fluid core, since molecular diffusivities are very small. Turbulence in the core is anisotropic because of the Earth's rotation, the gravity and the magnetic field. However, the effect of anisotropic turbulence on generation mechanism of the Earth's magnetic field is still unknown. In this research, direct numerical simulations for MHD turbulence are performed to examine the anisotropic turbulent transport. Then the turbulent transport is parameterized in terms of a second moment closure model. It turns out that such a model of turbulent transport expresses that obtained through direct numerical simulations. When an anisotropic eddy diffusivity is artificially employed in numerical simulations, it is found that the magnetic energy increases intermittently even if the kinetic energy is small. This suggests that anisotropic turbulent transport influences large-scale magnetic field generation. The turbulent heat transport is given by a product of an eddy diffusivity tensor and a temperature gradient vector. When an angle between directions of large-scale temperature gradient and gravity is larger than π/2, it is difficult to use a simple model for local turbulence in global numerical simulations.
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Research on the deep structure of active faults in the North Anatolian fault zone, Turkey
Grant number：11694063 1999 - 2000
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B).
HONKURA Yoshimori, OKUBO Shuhei, ITO Akihiko, OSHIMAN Naoto, MATSUSHIMA Masaki
Grant amount：\8600000 （ Direct Cost: \8600000 ）
We have established a seismic observation network called IZINET and monitored seismic activity.In this network, the Izmit earthquake of magnitude 7.4 occurred on August 17, 1999 and hence we could determine its hypocenter very accurately. The seismic data set obtained from IZINET is very important and many seismologists over the world have used this data set. We also made temporary observations to investigate the aftershock activity and we found a zone of seismic activity along the earthquake faults which appeared on the Earth's surface. The distribution of aftershocks is inhomogeneous and some clustering activities were found. This aftershock data set is also important and has been used by many seismologists over the world. From several years before the Izmit earthquake, the seismic activity was high in the epicentral area. Finally we pointed out that the focal mechanism and the aftershock distribution can provide some important clues for the next future large earthquake in the vicinity of Istanbul. As for electric and magnetic observations, records before, during and after the Izmit earthquake could be obtained. Careful examination of the records shows that the electric and magnetic fields changed drastically with the seismic waves. We interpreted these changes in terms of the seismic dynamo effect. In order to confirm this hypothesis, we made simultaneous seismio and electromagnetic observations at the same site. The records immediately before the Izmit earthquake are important from the viewpoint of earthquake prediction, but so far we have been unable to detect any anomalous changes in the electric and magnetic fields. We also made resistivity survey along some segments of the active fault and found that high resistivity zones prevail in the vicinity of the fault. We then pointed out that the hypocenter of the Izmit earthquake is just located in the high resistivity zone. Also most aftershocks tend to occur in this high resistivity zone.
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Three-dimensional MHD dynamo simulation
Grant number：10640404 1998 - 2000
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
HONKURA Yoshimori, MATSUSHIMA Masaki
Grant amount：\3100000 （ Direct Cost: \3100000 ）
Aiming at solving a dynamo problem as a mechanism of the origin of Earth and planetary magnetism, we have performed three-dimensional MHD dynamo simulation. So far, we have found that boundary layers develop depending on the Ekman number and in the layer small-scale phenomena are dominant, when a non-slip boundary condition is given to the velocity field. Therefore, we must evaluate the effect of boundary layers if we want to obtain reliable results of MHD dynamo simulation. In 1998 and 1999, we developed a new computer code for dynamo simulation and compared its results with those derived from our previous code and showed that our new code is valid. Then we modified this code so as to cope with parallel computing. In 2000, we have participated the dynamo benchmark test as an international group attempt. As a result, our results were found to agree with the others and therefore our computer code is as effective as the other codes developed by oversea researchers. From our results, we could find that crude spatial resolution in the radial direction greatly affects the drift rate of the velocity filed pattern. In other words, it is the most important to assure enough resolution in the boundary layers when we examine the results of numerical computation. A hypothetical cylinder, which is tangent to the inner core at its equator and parallel to the rotation axis, is called a tangent cylinder, which is also a boundary layer. The effect of this layer becomes prominent for the non-slip boundary condition. Inside the tangent cylinder, the flow is not violent when the Rayleigh number is small, but for a high Rayleigh number, convective motion becomes active, Such a feature has a great influence on the mechanism of magnetic field creation and variation. As a future work, we should try to under stand the dependence of the Rayleigh number on dynamics inside the tangent cylinder
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Farecast of Seismic Activity in the North Aratolian fault
Grant number：07044071 1995 - 1996
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for international Scientific Research
HONKURA Yoshinori, YAZICI-CAKIN O, MALIN S.R.C, PINAR A, VCER S.B, GURBUZ C, ISHIKARA A.M, MATSUSHIMA Masaki, OKUBO Shuhei, ITO Akihiko, OSHIMAN Naoto
Grant amount：\9900000 （ Direct Cost: \9900000 ）
The North Anatolian fault zone in northern Turkey has been considered to be a test field for earthquake prediction studies, because there exists a so-called seismic gap. The purpose of this research is to investigate the characteristics of earthquake generation through seismic studies and their relation to a large earthquake which has been considered to occur in the gap area in the future. In addition, continuous measurements of the geomagnetic and telluric fields have been made in the gap area to detect anomalies and clarify their mechanisms.
(1) Seismic observation
In order to monitor microseismic activity in the gap area, we have established a radio-linked seismic observation system consisting of a base station, where a three-component seismometer was set up, and five saztellite stations, where a vertical-component seismometer was installed. It was found from the observations that some microearthquakes have been occurring in the gap area, but the detection level for microseismicity turned out to be still insufficient. So we are now installing a few more stations.
(2) Strain measurement
A precise strainmeter was installed at a station located very close to an active fault in the gap area to monitor a possible strain change associated with fault displacement. However, the installation depth turned out to be too shallow to escape from the temperature effect and the observed data must be processed so as to remove this effect.
(3) Geomasgnetic and telluric measurements
Seven geomagnetic and two telluric stations have been in operation to monitor possible changes in the geomagnetic and telluric fields associated with earth quakes in the study area. So far we have obtained some examples of anomalous changes in the telluric field associated with some rather small earthquakes.
(4) Study of earthquake source process
We have analyzed seismic records of more than twenty events in Turkey, and detailed earthquake source processes have benn clarified in relation to tectonics. In particular, it was found that the 1967 Mudurnu Valley easrthquake has a complicated source process, this earthquake can be characterized generally by a strike-slip mechanism, but at its western end the normal-fault constituent was found. This is expected to provide a clue to the generation process of a large earthquake in the gap area, that is the west of the source area of the Mudurnu Valley earthquake. -
3次元MHDダイナモ並列計算による惑星磁場生成・維持機構の研究
Grant number：07454104 1995
日本学術振興会 科学研究費助成事業 一般研究(B)
本蔵 義守, 松島 政貴
Grant amount：\7700000 （ Direct Cost: \7700000 ）
「地球や惑星になぜ磁場が存在するのか?」は,未だに解明できていない地球惑星科学上の大問題である.その解決のためには,膨大な計算を必要とする,そして,非常に複雑な振る舞いをする3次元MHDダイナモ問題を精度よく解かなければならない.これまでは,磁場や速度場をポロイダル・トロイダル分解し,それらのスカラー関数を球面調和関数及び三角関数に展開して数値計算を行ってきた.しかしこの方法では,計算効率があまりよくなかった.また,局在する磁場の扱いにも問題が残った.そこで,本研究では,3次元MHDダイナモ計算専用の並列計算機を構築し,本格的地球惑星ダイナモの数値シミュレーションの実現を目指した.
並列計算機として,トランスピュータを採用した.これはMIMD(Multiple Instruction-Multiple Data)型・メモリ分散型の並列計算機であり,並列計算に必要となるトランスピュータ間のデータ転送のための接続をソフトウェアで行うことができる.計算対象領域となる回転球殻内に格子点を取り、解くべき方程式を差分化した.そして,計算領域を分割して個々のトランスピュータに割り当てることによって計算を並列化し,計算時間を短縮することを試みた.極となる回転軸上の点での差分化の問題解決のために,スカラー関数を軸対称成分と非軸対称成分とに分けた.そして,効率的な計算を行うための条件(球殻の分割の方法など)を得るために回転球殻内の熱対流の数値計算を行なった.今後は,本研究を契機として,本格的な3次元MHDダイナモの数値シミュレーションに取り組む予定である. -
並列処理を活かした地磁気ダイナモの数値計算
Grant number：07740369 1995
日本学術振興会 科学研究費助成事業 奨励研究(A)
松島 政貴
Grant amount：\1200000 （ Direct Cost: \1200000 ）
様々な時間スケールで変動している地球磁場の成因である地磁気ダイナモのメカニズムを解明することを目標とする.回転球殻内で熱対流を生じている電磁流体中で,磁場及び速度場が時間的・空間的にどのように振る舞うかを調べるために,磁場の誘導方程式,流体の運動方程式,そして熱の輸送方程式を解く.流体が非圧縮であると仮定すると,磁場も速度場もポロイダル成分とトロイダル成分とに分解できる.今までは,これらのスカラー関数を球面調和関数及び三角関数に展開して問題を解いてきたが計算効率がよくなかった.そこで,本研究では,効率よく計算するためにメモリ分散型の並列コンピュータを使用し,並列処理を行なうことにした.計算を並列化するために,計算領域となる球殻でメッシュを切り,差分化して方程式を解くことにした.球極座標系(γ,θ,φ)では回転軸(θ=0及びθ=π)が極となってしまうが,ポロイダル場及びトロイダル場のスカラー関数を,軸対称成分と非軸対称成分とに分解することにより極での計算を容易にした.
本研究の申請後,本学に新たにスーパーコンピュータが導入され,オートタスキングによる並列処理が可能となった。そこで,本研究で開発したコードの有用性を調べるために,スーパーコンピュータ(CRAY C916/12256)を利用した.8個のCPUを利用すると指定してプログラムを走らせたところ,8個のCPUを使っている時間が一番長くなり,並列化の効果があることがわかった.今後は,開発したコードを実際にダイナモ問題に応用しつつ,並列処理を活かしたより効率のよいコードになるように改良し,地球ダイナモ問題に取り組むつもりである. -
MT法による地殻内溶融体の研究
Grant number：06222211 1994
日本学術振興会 科学研究費助成事業 重点領域研究
本蔵 義守, 松島 政貴, 内田 利弘
Grant amount：\1500000 （ Direct Cost: \1500000 ）
日光白根火山の南東域に存在する地震波反射面に関して,比抵抗構造からアプローチとしてMT観測を計画し,ほぼ予定通りの観測を行うことができた。具体的には,約10km程度の深さに存在すると考えられている反射面の真上にあたる地域において8点観測点を選び,U36及びV5(AMT)による広帯域MT観測を行った.今回はV5(MT)が使用できなかったので,V5(AMT)で10,000Hz-10Hzの周波数帯を,U36で32Hz sampling及び1 Hz samplingを行うことにより,10Hz-0.1Hz,0.3Hz-0.01Hzそれぞれをカバーするようにした.AMTはremote-reference処理なしとし,低周波数帯に対しては,水沢のデータを利用することによってremote-reference処理を行う方針をとった.中間周波数帯に対しては,観測域内の適当な測点のデータを用いてremote-reference処理を行うことにした.現在までのところ,AMTの見かけ比抵抗及び位相にデータが得られている.全般に表層部は比抵抗が高く,いずれも100 ohm.m以上であり,なかには1000 ohm.m近いところもある.低周波数帯については,電化軌道からの漏洩電流によるノイズがひどいので,夜間のデータを解析している.
ただし,0.1Hzより高い周波数になるとシグナルレベルが急激に落ちるため,磁力計自体のノイズが問題となり,remote-reference処理が機能しなくなる傾向にある.以上,これまでの成果として,"(1)日光地域では,地殻深部はかなり高比抵抗(1000 ohm.mに近い)である,(2)ただし,周期数秒あたりになると100 ohm.m以下の低比抵抗を示す傾向が見られることから,地震波反射面が存在する深さに低比抵抗層が存在する可能性もある"とまとめられる. -
地磁気データから推定される地球核内部流体運動とヘリシティ
Grant number：06740353 1994
日本学術振興会 科学研究費助成事業 奨励研究(A)
松島 政貴
Grant amount：\900000 （ Direct Cost: \900000 ）
これまで,地球磁場の成因を解明するための一手段として,地磁気データを用いて地球核内部流体運動を推定してきた.本研究では,得られた速度場から液体核内部のヘリシティ分布を求めた.ヘリシティはダイナモ理論において重要な要素であり,α-効果に関係すると考えられている.
核-マントル境界付近では,大西洋側の半球において得られたヘリシティの絶対値は大きくなった.この結果は,凍結磁場近似に基づいて得られた核表面付近の流体運動から得られたヘリシティ分布と一致する.得られたヘリシティの経度方向平均は,赤道面に対してほぼ対称になった.しかしながら,南北半球におけるコリオリ力の働きは逆向きになるので,ヘリシティは反対符号になると考えられている.また,運動学的ダイナモはα-効果は赤道面反対称の分布を持つように与えられる.理由として考えられることは,本研究では大規模な流れのみを取り扱っているので,乱流的な小規模な流れの影響が反映されていないということである.ただし,大規模な流れの運動学的ダイナモでは,赤道面対称のヘリシティ分布を持つものでも,ダイナモとして成立するので,詳細に関しては,今後の研究が必要である.
運動学的ダイナモの研究では,ヘリシティの体積平均がダイナモの効率に関係することが示唆されている.本研究で得られたヘリシティからは,その平均値が小さいことがわかった.その理由として,観測されている中で,今は一番大きな磁場である双極子磁場が減少している時期であることや,さらに小規模な流体運動が磁場成因に対して大きな影響を持っていることなどが考えられるが,現段階では不明である.今後の研究が必要である. -
3次元MHDダイナモによる地球磁場逆転機構の研究
Grant number：05452072 1993
日本学術振興会 科学研究費助成事業 一般研究(B)
本蔵 義守, 松島 政貴
Grant amount：\7300000 （ Direct Cost: \7300000 ）
本研究では,「地球や惑星になぜ磁場が存在するのか?」,また「地球磁場はどのようなメカニズムでその極性を反転するのか?」という問題の解明を目的とした.
まず,地球磁場が地球中心核内の流体運動と磁場との相互作用(ダイナモ作用)によって生成・維持される機構の具体的プロセスを解明するために,地磁気ダイナモ問題を3次元非線形問題として定式化し,さらに数値計算に適した形にまとめた.その上で,強力なワークステーションを昼夜わかたず駆使し,磁場の時間発展をできる限り厳密に追うという作業を続けた.
その結果,適当なパラメータ領域で実際に流体運動によって磁場が維持されること,さらに磁場の極性がかなり規則的に逆転することが確かめられた.この結果は,磁場の極性逆転が非線形相互作用の結果としていわば自発的に起こることを示しており,磁場逆転の内因説を支持する.さらに,外核-マントル境界の温度が不均一に分布する場合,磁場が安定する傾向が見られ,極端な場合には磁場の逆転が起こらなくなることがわかった.
これらの結果をさらに一般化するために空間スケールをさらに細かくし,非常に複雑化した系を取り扱ったところ,電磁流体3次元問題の性質が実に複雑で,大きなスケールでの振る舞いを小さなスケールにあてはめることは危険であることがわかった.この問題は深刻で,数値計算において膨大な計算を行わない限り真の結果に到達できないことになる.
この問題に対処するために,本研究では並列計算機の構築を試み,ダイナモ並列計算のためのコードの開発を行っている.この作業は大変であり,現在も続行中であるがもうすぐ完成の見通しがたったところである. -
地磁気永年変化と地球核内の流体運動
Grant number：05740289 1993
日本学術振興会 科学研究費助成事業 奨励研究(A)
松島 政貴
Grant amount：\1000000 （ Direct Cost: \1000000 ）
地球磁場成因の解明に向けて、地磁気データを用いて、地球核内部流体運動の推定を行った。ポロイダル速度場の動径方向依存性を与え、磁場の誘導方程式およびナヴィエ-ストークス方程式を連立して解いた。これまでは、磁場の境界条件として、核表面における磁場の強度分布のみを与え、その時間変化は非常に小さいと仮定してきた。本研究では、地磁気永年変化も計算に取り入れた。ただし、速度場はこれまで同様、定常であると仮定した。そのため、誘導方程式から得られる、磁場の時間変化の変化(時間について2階微分)の式も解くべき方程式に加えた。
数値計算の結果得られた流体運動において、凍結磁場近似に基づいて得られている核表面付近の流れとの共通点が見つかった。本研究では、核全体が対流していると仮定したにもかかわらず、このような結果が得られたことから、凍結磁場近似に基づいて得られるような流体運動は、核内部の流れの現われであると考えられる。また、核の外には現れない、つまり地表では観測できないトロイダル磁場の強度は5×10^<-3>T程度となるという結果が得られた。このことは、地磁気ダイナモのメカニズムは、強いトロイダル磁場を作るalphaomega型ではないことを示唆している。
今後は、与えられているポロイダル速度場の動径方向依存性を変えて、その影響を調べていく必要がある。学会誌へは、現在、投稿準備中である。また、本研究の結果は、今年8月、カナダのウィッスラ-マウンテンで開かれるSEDI(Study of the Earth's Deep Interior)シンポジウムで発表する予定である。 -
地球惑星ダイナモの数値シミュレーション
Grant type：Competitive
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惑星磁場探査
Grant type：Competitive
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地球核内部流体運動の推定
Grant type：Competitive
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Numerical Simulation of the Earth and Planetary Dynamos
Grant type：Competitive
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Planetary Exploration with the Magnetic Field
Grant type：Competitive
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Estimation of Fluid Motion in the Earth's Core
Grant type：Competitive