1996 Fiscal Year Annual Research Report

大西洋中央海嶺に起きる群発地震の海底地震観測

Research Project

Project/Area Number	06044005
Research Institution	Hokkaido University
Principal Investigator	島村英紀北海道大学, 理学部, 教授 (10011636)
Co-Investigator(Kenkyū-buntansha)	ヒルンアルフレッドパリ第6大学, 地球物理学部, 教授ホワイトロバート英国ケンブリッジ大学, 海洋研究所, 教授アベディックフェリックフランス海洋庁, 海洋研究所, 主任研究員セレボールマークハードベルゲン大学, 固体地球物理学研究所, 教授ミエルデロルフベルゲン大学, 固体地球物理学研究所, 助教授ディグラネスパーベルゲン大学, 固体地球物理学研究所, 助教授グンナールソンカールアイスランド資源庁, 資源研究所, 研究主任アイナルソンポールアイスランド大学, 理学部, 教授ドッティルブリンディスアイスランド大学, 理学部, 助教授ベルグソンベルグールアイスランド気象庁, 地震火山研究部, 主任研究員グドムソングシナールアイスランド気象庁, 地震研究部, 主任ステファンソンラグナーアイスランド気象庁, 地震火山部, 部長岩崎貴哉東京大学, 地震研究所, 助教授 (70151719) 小平秀一海洋科学技術センター, 深海研究部, 主任研究員 (80250421) 塩原肇北海道大学, 理学部, 助手 (60211950)
Keywords	海底地震観測 / 海嶺の地震 / 海底地震計 / レイキャネス海嶺 / プレートの誕生 / 大西洋中央海嶺 / プレート・テクトニクス / 受動的海陸境界
Research Abstract	プレート・テクトニクスの焦点のひとつは海嶺でのプレートの誕生である。海嶺を詳しく調べるには、海底地震計を使った海底地震観測以上のものはない。それは、海底下に起きる地震は、プレートの動きの反映そのものであり、海嶺で起きているメカニズムを調べるためには最も直接の研究になるからである。私たちが開発した海底地震計を使って、この研究を行ってきている。いままでの本研究の結果を踏まえて、これらの地震活動がどういう地下構造のところで起きているのかを研究することが地球科学研究の急務になっているために1996年度では、地震活動の研究とともに、地下構造の解明のための研究も行った。研究はノルウェー・ベルゲン大学、アイスランド大学、ケンブリッジ大学などと共同として、アイスランド南方沖のノルウェー沖とレイキャネス海嶺付近とで行った。日本から海底地震計約30台を運び、ノルウェー側で用意した観測船でノルウェー沖の大西洋(約6000万年前に昔の大陸が割れて大西洋が誕生したころの痕跡が残っている海域)に海底地震計を設置して、人工地震を使った観測を行った。その後、アイスランド南方沖のレイキャネス海嶺でも海底地震計30台を設置して人工地震を使った研究と地震活動の観測を行った。海底地震計の設置と回収、それに人工地震を行う観測船はアイスランド側が用意した。この共同研究のために、英国とアイスランド側は陸上に臨時に地震計47台を設置した。この地震観測は、いままで大西洋中央海嶺で行われたうちでは世界的にも例が少ない大規模な海底地震観測であった。また国際学術研究の最終年度なので、各国から研究者を招へいして、各国それぞれがすでに独自に持っている観測データを今回のデータとつきあわせて、研究の取りまとめを行った。データが膨大であるためにまだ解析中ではあるが、今回の一連の実験の結果は地球科学の研究として画期的なものになる可能性が高い。

Research Products

(27 results)

All Other

All Publications (27 results)

[Publications] Shimamura,H.,Stefansson,R.,Mochizuki,M.,Watanabe,T.,Shiobara,H.,Gudmundsson,G.,and Einarsson,P: "Northern Reykjanes Ridge microseismicity revealed by dense OBS arrays" in Seismology in Europe,edited and published by European Seismological Commission,701pp.491-497 (1996)
[Publications] Kodaira,S,Mjelde,R.,Gunnarson,K.,Shiobara,H.,and Shimamura,H.: "Crustal structure of the Kolbeinsey Ridge,N.Atlantic,obtained by use of Ocean-Bottom Seismorgraphs" Journal of Geophysical Researches. 102(B2). 3131-51 (1997)
[Publications] Mjelde,R.,Fjellanger,J.P.,Digranes,P.,Kodaira,S.,Shimamura,H.,and Shiobara,H.: "Application of the single bubble airgun technique for OBS-data acquisition across the Jan Mayen Ridge,N Atlantic" Marine Geophysical Researches. 19. 81-96 (1997)
[Publications] Mjelde,R.,Kodaira,S.,Shimamura,H.,et al.: "The continent/ocean transition of the Lofoten volcanic margin,Northern Norway" Journal of Geodynamics. 22(3/4). 189-206 (1996)
[Publications] Mjelde,R.,Myhre,B.,Sellevoll,M.A.,Shimamura,H.,Iwasaki,T.,and Kanazawa T.: "Modeling of S-waves from an area covered with flood-basalt off Lofoten,Northern Norway" Geophysical Transactions. 40(1). 95-117 (1996)
[Publications] Kodaira,S.,Iwasaki,T.,Urabe,T.,Kanazawa,T.,Egloff,F.,Makris,J.and Shimamura,H.: "Crustal structure across the middle Ryukyu trench obtained from ocean bottom seismographic data" Tectonophysics. 263. 39-60 (1996)
[Publications] Mjelde,R.,Berg,E.W.,Shimamura,H.,et al.: "An extensive Ocean Bottom Seismograph survey in the Voring basin,N.Norway" First Break (EAGE). 14(6). 247-256 (1996)
[Publications] Kodaira,S.,Bellenberg,M.,Iwasaki,T.,Kanazawa,T.,Hirschleber,H.B.,and Shimamura,H.: "Vp/Vs ratio structure of the Lofoten continental margin,N.Norway,and its geological implications" Geophysical Journal International. 124. 724-740 (1996)
[Publications] Kodaira,S.,Mjelde,R.,Sellevoll,M.A.,Hirschleber,H.B.,Iwasaki,T.,Kanazawa,T.,and Shimamura,H.: "Crustal transect across the Lofoten volcanic passive continental margin,Northern Norway" Journal of Physics of the Earth. 43. 729-745 (1995)
[Publications] Kodaira,S.,Shimamura,H.,etc.: "Crustal Structure of the Lofoten continental margin,off northern Norway,from ocean-bottom seismographic studies" Geophysical Journal International. 121. 907-924 (1995)
[Publications] Mjelde,R.,Shimamura,H.et al.: "S-wave anisotropy off Lofoten,Norway,indicative of fluids in the lower continental crust?" Geophysical Journal International. 120. 87-96 (1995)
[Publications] Iwasaki,T.,Shimamura,H.et al.: "Seismic refraction study along the Sognefjord,south-west Norway,employing ocean-bottom seismometers" Geophysical Journal International. 119. 791-808 (1994)
[Publications] Goldschmidt-Rokita,A.,Shimamura,H.et al.: "The ocean/continent transition along a profile through the Lofoten Basin,Northern Norway" Marine Geophysical Researches. 16. 201-224 (1994)
[Publications] 望月將志,小平秀一,塩原肇,島村英紀,Bryndis Brandsdottir,Erik Sturkell,Ragnar Stefansson: "海底地震観測によるTjornes Fracture Zoneの地震活動" 『地震』,第2輯. 48. 257-270 (1995)
[Publications] Digranes,P.,Mjelde,R.,Kodaira,S.,Shimamura,H.,Kanazawa,T.Shiobara,H.,and Berg,E.W.: "A regional shear-wave velocity model in the central Voring Basin,N.Norway,using three-component OBS" Marine Geophysical Researches. (投稿中).
[Publications] Kodaira,S,Mjelde,R.,Sellevoll,M.A.,Hirschleber,H.B.,Iwasaki,T.,Kanazawa,T.,and Shimamura,H.: "Crustal transects across the Lofoten volcanic passive continental margin,N.Norway,obtained by use of OBS" Journal of Physics of the Earth. (投稿中).
[Publications] Mjelde,R.,Berg,E.W.,Strom,A.,Riise,O.,Shimamura,H.,Shiobara,H.,Kodaira,S.,and Fjellanger,J.P: "An extensive Ocean Bottom Seismorgraph survey in the Voring basin,N.Norway" Geophysical Journal International. (投稿中).
[Publications] Kodaira,S,Mjelde,R.,Shiobara,H.,Kanazawa,T.,Shimamura,H.,and Berg,E.W.: "Crustal Structure along the northern Voring continental margin,off N.Norway,from OBS data" Tectonophysics. (投稿中).
[Publications] Mjelde,R.,Kodaira,S.,Digranes,P.,Shimamura,Kanazawa,T.,Shiobara,H.,and Berg,E.W.: "Semi-regional crustal structure from densely spaced OBSs in the Voring Basin,N.Norway" Geophysical Journal International. (投稿中).
[Publications] Mjelde,R.,Kodaira,S.,Shimamura,Kanazawa,T.,Shiobara,H.,Berg,E.W.,and Riise,O.: "Crustal structure of the central part of the Voring Basin,N.Norway,from three-component OBS" Geophysical Journal International. (投稿中).
[Publications] Mjelde,R.,Kodaira,S.,Hassan,R.K.,Goldschmidt-Rokita,Sellevoll,M.A.,Hirschleber,H.B.,Shimamura,H.: "The continent/ocean transition of the Lofoten volcanic margin,N.Norway" Journal of Geodynamics. (投稿中).
[Publications] Mjelde,R.,Myhre,B.,Sellevoll,M.A.,Shimamura,H.,Iwasaki,T.,and Kanazawa,T.: "Modeling of S-waves from an area covered with flood-basalt off Lofoten,N.Norway" Biophysical Transactions. (投稿中).
[Publications] Shiobara,H.,Nakanishi,A.,Mjelde,R.,Kanazawa,T.,Berg,E.W.,and Shimamura,H.: "Precise determination of OBS positions by using acoustic transponders and CTD" Marine Geophysical Researches. (投稿中).
[Publications] Brandsdottir,B.,Shiobara,H.,White,R.,and Shimamura,H.: "RISE-96 OBS-land experiment to elucidate transitional structure from Reykjanse Ridge to Iceland" Geophysical Journal International. (投稿中).
[Publications] Mochizuki,M.,Brandsdottir,B.,Shiobara,H.,White,R.,Einarsson,P.,and Shimamura,H.: "Microseismicity study on the Northern tip of Reykjanes Ridge to Iceland revealed by dense OBS array." Journal of Geodynamics. (準備中).
[Publications] 島村英紀: "地震列島との共生" 岩波書店,科学ライブラリー, 128 (1996)
[Publications] 島村英紀: "地球がわかる50話" 岩波書店,ジュニア新書, 224 (1994)

1996 Fiscal Year Annual Research Report

大西洋中央海嶺に起きる群発地震の海底地震観測

Principal Investigator

島村 英紀 北海道大学, 理学部, 教授 (10011636)

Research Products

[Publications] Shimamura,H.,Stefansson,R.,Mochizuki,M.,Watanabe,T.,Shiobara,H.,Gudmundsson,G.,and Einarsson,P: "Northern Reykjanes Ridge microseismicity revealed by dense OBS arrays" in Seismology in Europe,edited and published by European Seismological Commission,701pp.491-497 (1996)

[Publications] Kodaira,S,Mjelde,R.,Gunnarson,K.,Shiobara,H.,and Shimamura,H.: "Crustal structure of the Kolbeinsey Ridge,N.Atlantic,obtained by use of Ocean-Bottom Seismorgraphs" Journal of Geophysical Researches. 102(B2). 3131-51 (1997)

[Publications] Mjelde,R.,Fjellanger,J.P.,Digranes,P.,Kodaira,S.,Shimamura,H.,and Shiobara,H.: "Application of the single bubble airgun technique for OBS-data acquisition across the Jan Mayen Ridge,N Atlantic" Marine Geophysical Researches. 19. 81-96 (1997)

[Publications] Mjelde,R.,Kodaira,S.,Shimamura,H.,et al.: "The continent/ocean transition of the Lofoten volcanic margin,Northern Norway" Journal of Geodynamics. 22(3/4). 189-206 (1996)

[Publications] Mjelde,R.,Myhre,B.,Sellevoll,M.A.,Shimamura,H.,Iwasaki,T.,and Kanazawa T.: "Modeling of S-waves from an area covered with flood-basalt off Lofoten,Northern Norway" Geophysical Transactions. 40(1). 95-117 (1996)

[Publications] Kodaira,S.,Iwasaki,T.,Urabe,T.,Kanazawa,T.,Egloff,F.,Makris,J.and Shimamura,H.: "Crustal structure across the middle Ryukyu trench obtained from ocean bottom seismographic data" Tectonophysics. 263. 39-60 (1996)

[Publications] Mjelde,R.,Berg,E.W.,Shimamura,H.,et al.: "An extensive Ocean Bottom Seismograph survey in the Voring basin,N.Norway" First Break (EAGE). 14(6). 247-256 (1996)

[Publications] Kodaira,S.,Bellenberg,M.,Iwasaki,T.,Kanazawa,T.,Hirschleber,H.B.,and Shimamura,H.: "Vp/Vs ratio structure of the Lofoten continental margin,N.Norway,and its geological implications" Geophysical Journal International. 124. 724-740 (1996)

[Publications] Kodaira,S.,Mjelde,R.,Sellevoll,M.A.,Hirschleber,H.B.,Iwasaki,T.,Kanazawa,T.,and Shimamura,H.: "Crustal transect across the Lofoten volcanic passive continental margin,Northern Norway" Journal of Physics of the Earth. 43. 729-745 (1995)

[Publications] Kodaira,S.,Shimamura,H.,etc.: "Crustal Structure of the Lofoten continental margin,off northern Norway,from ocean-bottom seismographic studies" Geophysical Journal International. 121. 907-924 (1995)

[Publications] Mjelde,R.,Shimamura,H.et al.: "S-wave anisotropy off Lofoten,Norway,indicative of fluids in the lower continental crust?" Geophysical Journal International. 120. 87-96 (1995)

[Publications] Iwasaki,T.,Shimamura,H.et al.: "Seismic refraction study along the Sognefjord,south-west Norway,employing ocean-bottom seismometers" Geophysical Journal International. 119. 791-808 (1994)

[Publications] Goldschmidt-Rokita,A.,Shimamura,H.et al.: "The ocean/continent transition along a profile through the Lofoten Basin,Northern Norway" Marine Geophysical Researches. 16. 201-224 (1994)

[Publications] 望月將志,小平秀一,塩原肇,島村英紀,Bryndis Brandsdottir,Erik Sturkell,Ragnar Stefansson: "海底地震観測によるTjornes Fracture Zoneの地震活動" 『地震』,第2輯. 48. 257-270 (1995)

[Publications] Digranes,P.,Mjelde,R.,Kodaira,S.,Shimamura,H.,Kanazawa,T.Shiobara,H.,and Berg,E.W.: "A regional shear-wave velocity model in the central Voring Basin,N.Norway,using three-component OBS" Marine Geophysical Researches. (投稿中).

[Publications] Kodaira,S,Mjelde,R.,Sellevoll,M.A.,Hirschleber,H.B.,Iwasaki,T.,Kanazawa,T.,and Shimamura,H.: "Crustal transects across the Lofoten volcanic passive continental margin,N.Norway,obtained by use of OBS" Journal of Physics of the Earth. (投稿中).

[Publications] Mjelde,R.,Berg,E.W.,Strom,A.,Riise,O.,Shimamura,H.,Shiobara,H.,Kodaira,S.,and Fjellanger,J.P: "An extensive Ocean Bottom Seismorgraph survey in the Voring basin,N.Norway" Geophysical Journal International. (投稿中).

[Publications] Kodaira,S,Mjelde,R.,Shiobara,H.,Kanazawa,T.,Shimamura,H.,and Berg,E.W.: "Crustal Structure along the northern Voring continental margin,off N.Norway,from OBS data" Tectonophysics. (投稿中).

[Publications] Mjelde,R.,Kodaira,S.,Digranes,P.,Shimamura,Kanazawa,T.,Shiobara,H.,and Berg,E.W.: "Semi-regional crustal structure from densely spaced OBSs in the Voring Basin,N.Norway" Geophysical Journal International. (投稿中).

[Publications] Mjelde,R.,Kodaira,S.,Shimamura,Kanazawa,T.,Shiobara,H.,Berg,E.W.,and Riise,O.: "Crustal structure of the central part of the Voring Basin,N.Norway,from three-component OBS" Geophysical Journal International. (投稿中).

[Publications] Mjelde,R.,Kodaira,S.,Hassan,R.K.,Goldschmidt-Rokita,Sellevoll,M.A.,Hirschleber,H.B.,Shimamura,H.: "The continent/ocean transition of the Lofoten volcanic margin,N.Norway" Journal of Geodynamics. (投稿中).

[Publications] Mjelde,R.,Myhre,B.,Sellevoll,M.A.,Shimamura,H.,Iwasaki,T.,and Kanazawa,T.: "Modeling of S-waves from an area covered with flood-basalt off Lofoten,N.Norway" Biophysical Transactions. (投稿中).

[Publications] Shiobara,H.,Nakanishi,A.,Mjelde,R.,Kanazawa,T.,Berg,E.W.,and Shimamura,H.: "Precise determination of OBS positions by using acoustic transponders and CTD" Marine Geophysical Researches. (投稿中).

[Publications] Brandsdottir,B.,Shiobara,H.,White,R.,and Shimamura,H.: "RISE-96 OBS-land experiment to elucidate transitional structure from Reykjanse Ridge to Iceland" Geophysical Journal International. (投稿中).

[Publications] Mochizuki,M.,Brandsdottir,B.,Shiobara,H.,White,R.,Einarsson,P.,and Shimamura,H.: "Microseismicity study on the Northern tip of Reykjanes Ridge to Iceland revealed by dense OBS array." Journal of Geodynamics. (準備中).

[Publications] 島村英紀: "地震列島との共生" 岩波書店,科学ライブラリー, 128 (1996)

[Publications] 島村英紀: "地球がわかる50話" 岩波書店,ジュニア新書, 224 (1994)

島村英紀北海道大学, 理学部, 教授 (10011636)