Ocean Bottom Seismographic Survey of the Earthquake Swarm which occur beneath Mid Atlantic Ridge.

对大西洋中脊下方发生的地震群进行海底地震调查。

• 批准号: 06044005
• 负责人: SHIMAMURA Hideki
• 金额: $ 11.65万
• 依托单位: Hokkaido University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for international Scientific Research
• 财政年份: 1994
• 资助国家: 日本
• 起止时间: 1994 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-06044005/
• 关键词: Ocean Bottom Seismographic Observations; Earthquakes of Mid-Ocean Ridges; Ocean Bottom Seismograph; Reykjanes Ridge; Birth of a (lithospheric) plate; Mid-Atlantic Ridge; Plate tectonics; Passive plate margin; 単一パルスエアガン; 海底微小地震観測

Mid-Atlantic Ridge is the place where plate (lithosphere) is being born.. Because usual land-based seismographs are too far to study Ridges, we made use of 30-50 sensitive portable OBSs (Ocean Bottom Seismographs) to make detailed microearthquake observations and refraction studies to study detailed crustal/upper mantle structures. Also we studied Atlantic passive margins, which is a remnant of spreading of the Atlantic Ocean.We brought about 30 OBSs to the Atlantic in 1994,1995 and 1996. In 1994 we made two experiments in the Atlantic : one on the Reykjanes Ridge and the other in the Bay of Biscay. In the former, we succeeded to obtain a detailed hypocentral distribution of microearthquakes, and the structure beneath the Ridge. In the latter, we succeeded to develop a powerful controlled source survey to study crustal/upper mantle structure, with a combination of the single-bubble pulse airgun and the sensitive OBS.In 1995 we made an extensive OBS-airgun refraction survey in a region … More from Kolbeinsey Ridge, which is a part of Mid-Atlantic Ridge north of Iceland, to Jan Mayn Ridge, which is thought a remnant continent before the Atlantic was born. We have succeeded to obtain a continuous detailed structure for the whole transect from Kolbeinsey Ridge to Jan Mayn Ridge, which is quite important to study the history of opening of the Atlantic Ocean.In 1996 we also made two experiments in the Atlantic : one on the Voring Basin off Norway and the other in the transition from Reykjanes Ridge to Iceland. The former was to illustrate a very detailed crustal structure off Norway, where a remnant initiation of the opening of the Atlantic is kept beneath the flow basalt. The flow basalt is very impenetrable rock for the usual seismic reflection method used in the sea, however our OBS refraction survey can penetrate beneath the layr. The latter was to study micro-earthquakes beneath the transition from Reykjanes Ridge to Iceland which is essential to study how Iceland and the Ridge was formed. We also made controlled source study in this area to elucidate detailed crustal structure of the transition. We used 30 OBS plus 47 temporary land seismographs for this study. Less

中大西洋山脊是植物（岩石圈）诞生的地方。由于通常的陆基地震仪太远，无法研究山脊，所以我们使用30-50个敏感的便携式观测值（海洋底部地震仪）来进行详细的微型测序观测和折射研究，以研究详细的corlustal corlustal/toppers loppers loppers lastle架子结构。我们还研究了大西洋的被动边缘，这是大西洋传播的残余。我们于1994年，1994年和1996年将大约30个观察到大西洋。1994年，我们在大西洋进行了两个实验：一个在雷克雅内斯山脊上进行了两次实验，另一个在比斯卡斯海湾进行。在前者中，我们成功地获得了微夸克斯和山脊下的结构的详细的下中心分布。在后者中，我们成功地开发了一项强大的受控源调查，以研究地壳/上地幔结构，结合了单粉脉搏气枪和敏感的观察。出生。我们成功地获得了从Kolbeinsey Ridge到Jan Mayn Ridge的整个样带连续的详细结构，这对于研究大西洋开放的历史非常重要。1996年，我们还在大西洋进行了两个实验：一个在挪威瓦斯盆地和另一个在Reykjanes Rekjanes Ridge到Iceland的过渡。前者是为了说明挪威非常详细的地壳结构，在该结构中，大西洋开放的残余倡议被保存在流向玄武岩下方。对于在海洋中使用的通常地震反射方法来说，流量玄武岩是非常难以穿透的岩石，但是我们的OBS折射调查可以穿透在Layr下方。后者是在从雷克雅内斯山脊到冰岛的过渡下研究微观，这对于研究冰岛和山脊的形成至关重要。我们还在该领域进行了对照源研究，以阐明过渡的详细地壳结构。我们在这项研究中使用了30个OBS加47个临时土地地震仪。较少的

项目成果

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).

Brandsdottir, B.、Shiobara, H.、White, R. 和 Shimamura, H.：“RISE-96 OBS 陆地实验阐明从雷克詹斯海岭到冰岛的过渡结构”《国际地球物理杂志》（已提交）。

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)

Masashi Mochizuki、Shuichi Kodaira、Hajime Shiobara、Hideki Shimamura、Bryndis Brandsdottir、Erik Sturkell、Ragnar Stefansson：“基于海底地震观测的 Tjornes 断裂带地震活动”，地震，卷 2. 48. 257-270 (1995)

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).

Shiobara, H.、Nakanishi, A.、Mjelde, R.、Kanazawa, T.、Berg, E.W. 和 Shimamura, H.：“使用声学转发器和 CTD 精确确定 OBS 位置”海洋地球物理研究）。

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)

Mjelde,R.、Berg,E.W.、Shimamura,H.等人：“在挪威北部沃林盆地进行广泛的海底地震仪调查”首次突破 (EAGE)。

Mjelde, R., Kodaira, S., Hassan, R.K., Goldschmidt-Rokita, Tomita, N., Sellevoll, M.A., Hirschleber, H.B., Shimamura, H., Iwasaki, T., and Kanazawa: "The continent/ocean transition of the Lofoten volcanic margin, N.Norway" Journal of Geodynamics. 22 (3/4)

Mjelde, R.、Kodaira, S.、Hassan, R.K.、Goldschmidt-Rokita、Tomita, N.、Sellevoll, M.A.、Hirschleber, H.B.、Shimamura, H.、Iwasaki, T. 和 Kanazawa：“大陆/海洋转变