DESCRIPTION OF SUBMARINE ACTIVE FAULTS AROUND JAPANESE ISLANDS-A BASIC INVESTIGATION FOR SUBMERSIBLE SEISMOGEOLOGY-

日本列岛周边海底活动断层描述-潜水式地震地质基础调查-

基本信息

批准号：
06640577
负责人：
TAKEUCHI Akira
金额：
$ 1.41万
依托单位：
TOYAMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06640577/
关键词：
Plate boundary Active fault Research Submersible Seismogeology Tectonics Trench Tsunami Japanese Island arcs バクテリアマット

项目摘要

Results of the two years project for submarine seismogeology are summarized methodologically and tactically as follows :Since most active faults surrounding JapaneseIslands locate along boundaries between submarine ridges and basins similarly as on land, they can be roughly located if surface ship data of seismic profiling surveys are available. Direct observation of active faults on the bottom, however, is rather difficult because the more active faults tends to be buried easily by turbulent bottom current due to their own seismic activities. Not almighty but effective indicators used as markers in searching for submarine active faults are altered-color mats, including authigenic chemical deposits, bacterial mats, and fields of clam colonies. In addition, zones of fresh debris, ground fissures, brand-new fault scarplets which cut the recent sediments, fresh slickenlines on fault planes, and so on, are also available.Submarine co-seismic diastrophism in the northern epicenter area of t … More he 1993 South-western off Hokkaido earthquake was reported for the first time in the world. The report includes the new identifications of 1) "quake-rubble" characterized as autochtonous brecciation of unconsolidated mud layr and 2) "jump-fall rubble" scarcely distributed on the muddy flat-floor in front of steep scarps due to slope failure and/or landslide, which denote the strong motions during the main-shock and were visibly observed by submersible investigations.Seismotectonics along the eastern Nankai Trough werere-investigated on the basis of photographic analyzes of still-photos and video films recorded during the KAIKO and KAIKO-NANKAI programs, using structural indicators such as slip sense of fault, clastic dikes and joints. Tectonic stress orientation differs among the inner and outer tough slopes, indirectly indicating eastern motion of the Amurian plate (Enshu-nada deepsea terrace) and northward motion of the Philippine Sea plate (Zenisu Ridge). On the contrary, no such kind of stress zonation is found along the eastern maegin of Japan Sea, possibly because the plate boundary between the Amur and the Okhotsk plates are too immature. Less

两年来的海底地震地质学项目的结果在方法和战术上总结如下：由于日本列岛周围的大多数活动断层与陆地上一样位于海底脊和盆地之间的边界上，因此如果地震剖面调查的水面船舶数据是可以粗略定位的。然而，直接观测底部的活动断层是相当困难的，因为较活跃的断层由于其自身的地震活动而容易被底部湍流所掩埋。用于寻找海底活动断层的万能而有效的指标是变色垫，包括自生化学沉积物、细菌垫和蛤群地，此外，还有新鲜碎片、地裂缝、全新断层猩红区。还可以得到近期沉积物的切割、断层面上的新鲜光滑线等。 1993年北海道西南部地震在世界上首次报道，该报告包括新的鉴定：1）以松散泥层的自生角砾岩为特征的“地震碎石”和2）几乎不分布的“跳落碎石”。由于斜坡失稳和/或山体滑坡，位于陡峭陡坡前的泥泞平坦地面上，这表示主震期间的强烈运动，并且可以明显观察到基于 KAIKO 和 KAIKO-NANKAI 计划期间记录的静态照片和视频的孪生摄影，利用断层滑移感、塑性堤和节理等结构指标，重新研究了南海海槽东部的地震构造。内外坚斜坡构造应力方向不同，间接表明阿穆尔板块（远州滩深海阶地）东移和北海板块北移。相反，在菲律宾海板块（泽尼苏海岭）沿日本海东部则没有发现这种应力分带，可能是因为阿穆尔板块和鄂霍茨克板块之间的板块边界太不成熟。