Research for deep back-arc structure in Mariana by Japan-US joint long-term seismic observation

日美联合长期地震观测研究马里亚纳深部弧后构造

• 批准号: 16540378
• 负责人: SHIOBARA Hajime
• 金额: $ 2.43万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2004
• 资助国家: 日本
• 起止时间: 2004 至 2005
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-16540378/
• 关键词: Mariana; deep events; mantle structure; double seismic zone; ocean bottom seismic observation

FY2004Recovery of LTOBS deployed for the US-JP joint long-term seismic observation in Mariana started in 2004 was performed in April and May. Although 58 LTOBS were deployed, the overall data recovery was about 80%. On 20-21 May, the US side chief, Prof.Wiens visited Japan and we discussed about the data exchange and analysis. Preliminary analysis of this data, hypocenter determination, seismic activities along the spreading center in the back-arc and around the large serpentine seamount in the fore-arc were found. As these were also found in the pilot study experiment in 2001, these are assumed as steady activities. Farther more, a simultaneous inversion for hypocenter and 3-D velocity structure had been performed too by using arrival data for one year. Due to more than 3000 events originally detected, it could image the subducting Pacific plate even if without priori information of it. More precise hypocenter distribution obtained certified the systematic shift of epicenters determin … More ed by land stations. These result was presented in the AGU meeting in Dec.FY2005Cooperative study with US scientists was continued as same in the previous year. Further more, a dive recovery for un-recovered LTOBS in Mariana was conducted in July, and 3 LTOBS related with this study were successfully recovered. So that, all usable data obtained from two experiments became available, and the final data exchange between Japan and USA was also finished. From the 2001 data with 2 more LTOBS recovered this year, whole arrival data was checked again, then the simultaneous inversion was performed again. As additional LTOBS improved the station distribution, shallow seismic activity in the back-arc was revealed with high resolution. The double seismic zone also shows a fine structure, which starts from beneath the serpentine seamount of its upper plane. The new data obtained in 2003 was analyzed mainly in US side such as S-wave splitting, surface wave analysis, hypocenter determination and body wave tomography. These results were presented in the AGU meeting by aural and posters. Less

2004财政年度4月和5月，为2004年开始在马里亚纳进行的美国-日本联合长期地震观测而部署的LTOBS进行了恢复。虽然部署了58个LTOBS，但整体数据恢复率约为80%。5月20日至21日，美方负责人威恩斯教授访问了日本，我们讨论了数据交换和分析的问题。对这些数据进行了初步分析，确定了震源，发现了弧后沿沿着扩张中心和弧前大型蛇纹海山周围的地震活动，由于这些活动在2001年的先导研究实验中也发现了，因此假定这些活动是稳定的。利用一年多的到时资料，同时反演了震源和三维速度结构。由于原始观测到的3000多个地震，即使没有太平洋板块俯冲的先验信息，它也能对太平洋板块俯冲进行成像，得到了更精确的震源分布，证实了确定太平洋板块俯冲的震中系统性移动。 ...更多信息 艾德被陆地电台广播。这些结果在2005年12月的AGU会议上公布，与美国科学家的合作研究与前一年一样继续进行。此外，7月在马里亚纳进行了未回收LTOBS的潜水回收，成功回收了3个与本研究相关的LTOBS。这样，两次试验获得的可用数据全部可用，并完成了日美间的最终数据交换。从2001年的数据和今年恢复的2个LTOBS，再次检查整个到达数据，然后再次进行联合反演。由于附加的LTOBS改善了台站分布，弧后浅层地震活动以高分辨率显示出来。双地震带还显示出一个精细结构，它始于其上平面的蛇形海山之下。对2003年新资料的分析主要集中在美国方面，如横波分裂、面波分析、震源定位和体波层析成像等。这些结果在AGU会议上通过听觉和海报进行了介绍。少

项目成果

Depth of the 660-km discontinuity near the Mariana slab from an array of ocean bottom seismographs

来自一系列海底地震仪的马里亚纳板块附近 660 公里不连续的深度

• 发表时间: 2006
• 期刊: Geophys. Res. Lett. 33
• 作者: Tibi R.;D.A.Wiens;H.Shiobara;H.Sugioka;P.J.Shore
• 通讯作者: P.J.Shore

Long term seismic observation in Mariana by OBSs : double seismic zone and upper mantle structure

马里亚纳OBS长期地震观测：双地震带和上地幔结构

• 发表时间: 2005
• 作者: H. Shiobara;H. Sugioka;K. Mochizuki;S. Oki;T. Kanazawa;Y. Fukao;K. Suyehiro
• 通讯作者: K. Suyehiro