Monitering of submarine crustal activity by ocean acoustic waves and ocean-seismic waves

利用海洋声波和海洋地震波监测海底地壳活动

基本信息

批准号：
10440125
负责人：
FUKAO Yoshio
金额：
$ 8.32万
依托单位：
University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-10440125/
关键词：
submarine volano OBS ocean acoustic waves seismic waves 海底 T-phase

项目摘要

(1) Study of anomalous submarine earthquakes by ocean acoustic wavesAn anomalous submarine earthquake with the CLVD mechanism happened near Torishima Island. We found that this earthquake generated a series of ocean acoustic wave trains. The analysis of the OBS records of these waves lead us to conclude that the crustal deformation associated with the CLVD earthquake squeezed magma fluid in the source region upward, that the ascent of the magma fluid generated volcanic earthquakes whose foci migrated upward progressively, and that these earthquakes generated a series of ocean acoustic wave trains.(2) Detection of submarine seismic activity by ocean-coupled shear wavesWe detected a series of events that generated "T phase-like" waves and found that they were the shallowest submarine seismic activity in a very localized area off Boso, Japan. Our theoretical study indicates that the observed "T-like" waves are the sediment-trapped shear waves coupled with ocean acoustic waves multiplly reflected at the sea surface. We named these waves "ocean-coupled sedimentary shear waves" which should be useful to detect any submarine shallowest activity.(3) Study of submarine volcanic activity by ocean acoustic wavesThe seismograms of OBS cable arrays often record ocean acoustic waves due to submarine volcanic activities. We located the origins of these waves near the northern end of the Mariana volcanic arc. The analysis of these waves indicate that the volcanic activity often starts gradually and stops abruptly and that ocean acoustic waves become more rich in lower-frequency content as the activity becomes more intense. We also detected a semi-diurnal migration of the T-phase origins, which is perhaps an apparent one due to the tidal effect of the velocity structure of the ocean.

（1）研究与CLVD机制的海洋声波异常海底地震的异常潜艇地震发生在Torishima Island附近。我们发现这次地震产生了一系列海洋声波列车。 The analysis of the OBS records of these waves lead us to conclude that the crustal deformation associated with the CLVD earthquake squeezed magma fluid in the source region upward, that the ascent of the magma fluid generated volcanic earthquakes whose foci migrated upward progressively, and that these earthquakes generated a series of ocean acoustic wave trains.(2) Detection of submarine seismic activity by ocean-coupled shear wavesWe发现了一系列产生“ T相样”波的事件，发现它们是日本Boso附近非常本地化的地区最浅的海底地震活动。我们的理论研究表明，观察到的“ T样”波是被沉积物捕获的剪切波和海洋声波偶数反射在海面。我们命名了这些波浪“海洋耦合的沉积剪切波”，对于检测任何最浅的活性应该是有用的。（3）通过海洋隔音浪潮对OBS电缆阵列的海洋阵列图进行研究，通常记录由于海底燃料燃料活动而导致的海洋声波。我们在玛丽安娜火山弧的北端附近找到了这些波的起源。对这些波的分析表明，随着活动变得更加激烈，火山活动通常逐渐逐渐开始并突然停止，海洋声波变得更加丰富。我们还检测到了T阶段起源的半衰变迁移，这可能是由于海洋速度结构的潮汐作用而显然是一种迁移。