Intersected Structure and Superpose Tectonics between the Eastern Margin of Japan Sea and the Toyama Trough, central Japan

本研究利用多窄波束条带测深和侧扫声纳声学成像以及浅地层剖面仪在日本海域进行了地貌调查，结果表明：（1）上新世和后来的褶皱和相关断裂发育了甲烷水合物表层，其深度与潜水器观察到的海底最上层的出露深度一样浅。可以肯定的是，类似于盐丘的水合物丘已经形成在构造高点，甲烷的迁移和上涌位于沿着背斜轴。在陆地上，我们继续对目前正在进行的地壳变形进行GPS大地测量监测。研究结果证实了活动断裂在海陆两个区域的分布以及它们之间的交叉关系。我们对日本最活跃的断层之一Atotsugawa断层系统的地震地质调查清楚地表明，在1858年的最新事件中，发震断层的东半部也被激活，西部也是如此，这表明基底结构在N-S走向和NE-SW走向的软弱带（称为新潟-神户构造带）中的深部交汇。为了解决交汇的动力学问题，推进物理学、大地测量学、地质学等物质科学的综合研究，探讨构造现象与孕震区下地壳现象的力学关系。2008年及以后，我们参加了日本海东缘沿着构造应变集中带的五年研究和监测计划。

This study had conducted geomorphologic survey utilizing multi-narrow beam swath bathymetry and acoustic imaging by side scan sonar and sub-bottom profiler in the Japan sea-area, As the results the following were elucidated (1) The Pliocene and later folding and related fracturing had developed surfacial layers of methane hydrate as shallow as the uppermost layer is outcropped on the sea bottom to be observed by the submersible vehicle. It was assured that hydrate domes similar to salt domes have been formed on structural highs where migration and upwelling of methane are localized along the anticline axes.On land, we have continued our GPS geodetic monitoring of the present-day ongoing crustal deformation. The results confirmed the distribution of active faults across both regions in land and sea, and also intersecting relationships among them. Our seismo-geological surveys on the Atotsugawa fault system, one of the most active faults in Japan, made clear that the eastern-half segment of seismogenic faults had also been activated at the latest event in 1858 as well as the western, suggesting the deep intersection of basement structure in a N-S trend and NE-SW trending weak zone called the Niigata-Kobe tectonic belt.In order to resolve the dynamics of intersection, we will promote an integrated comprehensive study among geophysics, geodesy, geology and other material sciences on the mechanical relationship between tectonic phenomena and those in the lower crust beneath seismogenic zone. In 2008 and after, we join the five-year research and monitoring program for the zone of tectonic strain concentration along the eastern margin of Japan Sea.