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Study of Submarine Landslides, Its Mechanism, Time, and Prediction

海底滑坡及其机制、时间和预测研究

基本信息

批准号：
01540634
负责人：
NEMOTO Kenji
金额：
$ 0.96万
依托单位：
Tokai 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：
1989
资助国家：
日本
起止时间：
1989 至 1990
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-01540634/
关键词：
Submarine Landslide Suruga Bay Nothern Senoumi-Tai Earthquake Ansei Earthquake Submarine Geology Sedimentology Study on Gravels 音波探査断層運動礫の変形

项目摘要

Geological and geophysical data taken by Tokai Univ. and existing data sets from other institutions are analyzed to study mechanism, timing and future prediction of submarine landslide on the slope of Senoumi-Tai in the Suruga Bay, Japan. Conclusions of this study are summarized as follows.(1) Newly constructed bathymetric chart indicates presence of several topography depressions which clearly show morphological characteristics of submarine landslide on the western and northern slopes of the northern Senoumi-Tai in the Suruga bay. (2) 3.5KHz echogram records show that this feature was caused by sudden loss of surface sedimentary layer about 100m in thickness. Creeps of surface layer are also identified and interpreted as onset of future submarine slide. (3) Analysis o f large amounts of seismic reflection records results in understanding of geological structure and geological developments on western part of the bay. It is clarified that the northern Senoumi-Tai has being uplifted by i … More ntensive tectonism during middle to late Quaternary and this uplifting process is still undertaking. As a result of this uplift, old eastward flowing canyon was not able to flow anymore and new submarine canyon system started to develop along the base of western slope of the northern Senoumi-Tai and flow northward. Intensive erosion at this location and uplift of Senoumi-Tai itself created unstable slope condition and generated creeps on the western slope of the Senoumi-Tai. One of the gigantic earthquakes appears to be a trigger of the slide. Historical record suggests appearance of huge water column and generation of tsunami during Ansei earthquake in 1854. This record suggests the relation between the earthquake and the submarine land slide at the Senoumi-Tai. Debris flow are found at the northern part of the Senoumi Basin and thought to be formed by the landslide. (4) Sedimentological study defines sedimentally environments, such as sea floors characterized by continuous sedimentation, sedimentation with sudden interruption, and chaotic sedimentation, probably debris flow. (5) Gravels are dredged on the summit of the northern Senoumi and found to be derived from dominantly Abe and partly Ooi river. (6) Datings of piston core samples are examined by analysis of pollen fossils contained in sediments. Three fossil zones are identified (before 3000 years, 3000-the middle age, the middle age - present). This time stratigraphy is applied to core sample from submarine landslide in order to determine timing of the slide and suggests that the time of landslide appears to be post-middle age. (7) Relation between submarine landslide and generation of tsunami is studied by simulation on computer system. This study indicates that landslide may be able to cause tsunami under certain conditions. Less

通过分析东海大学的地质和地球物理资料以及其他机构的现有资料，研究了日本骏河湾仙之见台斜坡海底滑坡的机制、时间和未来预测。本研究的结论总结如下。(1)新绘制的等深线图显示，骏河湾仙之见台北方的西、北方斜坡存在多处地形凹陷，清楚地显示了海底滑坡的形态特征。(2)3.5KHz回波记录表明，这一特征是由于表层沉积层厚度约100 m的突然消失造成的。表层蠕变也被确定和解释为未来的海底滑坡的开始。(3)通过对大量地震反射记录的分析，了解了海湾西部的地质构造和地质发展情况。阐明了北方塞努米台地区的隆升是由于 ...更多信息中晚第四纪强烈的构造作用，这一隆升过程至今仍在进行。由于这一隆起，旧的向东流动的峡谷不再能够流动，新的海底峡谷系统开始沿着仙之见台北方西部斜坡的底部向北流动。在这个位置的强烈侵蚀和Senoumi-Tai本身的隆起造成了不稳定的斜坡条件，并在Senoumi-Tai的西部斜坡上产生蠕变。其中一次大地震似乎是滑坡的触发器。历史记录显示，1854年安西地震时出现了巨大的水柱，并产生了海啸。这一记录表明了地震与仙之见台海底滑坡之间的关系。在Senoumi盆地的北方发现了泥石流，并认为是由滑坡形成的。(4)沉积学研究定义了沉积环境，例如以连续沉积为特征的海底、突然中断的沉积和混乱的沉积，可能是泥石流。(5)在北方Senoumi的山顶上挖掘砾石，发现主要来自Abe河，部分来自Ooi河。(6)通过对沉积物中所含花粉化石的分析，对活塞岩心样品的年代进行了检验。确定了三个化石带（3000年前，3000年-中期，中期-现在）。通过对海底滑坡岩样进行时间地层学分析，确定了滑坡发生的时间，认为滑坡发生的时间为中晚期。(7)利用计算机模拟系统研究了海底滑坡与海啸发生的关系。研究表明，滑坡在一定条件下可能引发海啸。少