Hypocenter determination by Japan-Taiwan collaborative research to presume Philippine sea plate zone in the vicinity of Ryukyu Arc to Eastern Taiwan region.

日本与台湾合作研究确定震源，推测琉球岛弧至台湾东部地区的菲律宾海板块带。

基本信息

批准号：
14540399
负责人：
BABA Hisatoshi
金额：
$ 1.6万
依托单位：
TOKAI UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

项目摘要

Geology and tectonics of the region between the southwestern Ryukyu arc and the eastern Taiwan are characterized by subduction or collision of the Philippine Sea plate and Eurasian plate. The present collision boundary in Taiwan is located along the Longitudinal Valley between Hualien and Taitung, but the plate boundary of the region between the northeast off Taiwan and the southwestern Ryukyu arc is not yet clear and still controversial. In order to make clear the plate boundary or configuration and tectonics in the region, it is indispensable to study the accurate seismic activities, in other words, precise hypocenter distributions, focal mechanisms, and so on.We, therefore, have been able to obtain more accurate or detailed hypocenter distributions in this region. As the results, our hypocenter locations show a large discrepancy with those of Japan Meteorological Agency and Taiwan Central Weather Bureau, which may be due to biased station networks, complex lithospheric structures and others, in this area. Recently, within a half year, four large earthquakes occurred near Yonaguni Is. (Dec.18 2001, M7.3), near Ishigaki Is. (Mar.15 2002, M6.6), and off east coast of Taiwan (Mar.31 2002, M7.2, and May.15 2002, M6.8). These earhtquake focal zones seem to align along the plate boundary, and their focal mechanisms are reflected on a complicated tectonics in the region. We describe the precise hypocentral distribution, and fault plane model of earthquake. Also we make consideration about the cause of the activity and the tectonics.

琉球岛弧西南侧与台湾东部之间的地区地质构造以菲律宾海板块与欧亚板块俯冲或碰撞为特征。台湾目前的碰撞边界位于花莲与台东之间的纵谷沿线，但台湾东北部与琉球岛弧西南地区的板块边界尚不明确，仍有争议。为了明确该地区的板块边界或构造和构造，必须研究准确的地震活动，即精确的震源分布、震源机制等。因此，我们能够获得该区域更准确或更详细的震源分布。结果表明，我们的震源位置与日本气象厅和台湾中央气象局的震源位置存在较大差异，这可能是由于该地区台网偏差、岩石圈结构复杂等原因造成的。最近，半年内，与那国岛附近发生了四次大地震。（2001 年 12 月 18 日，M7.3），石垣岛附近。（2002年3月15日，M6.6），以及台湾东海岸（2002年3月31日，M7.2，2002年5月15日，M6.8）。这些地震震源区似乎沿着板块边界排列，其震源机制反映在该地区复杂的构造上。我们描述了精确的震源分布和地震断层面模型。我们还考虑了活动的原因和构造。