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Investigation for the mechanism of the seismic damage band on Nobi earthquake

浓尾地震震害带机制研究

基本信息

批准号：
12480110
负责人：
FUKUWA Nobuo
金额：
$ 10.37万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12480110/
关键词：
Nobi plain surface soil structures investigation of soil structure Active faults seismic observation tremor forecast of strong motion Nankai trough 地震調査南海トラフト濃尾地震

项目摘要

We investigated the mechanism of the seismic damage band that have been observed on the 1891 Nobi earthquake. We have obtained following resuts :We have analyzed many data of underground structure of Nobi plain, and compiled them with the results of investigation of deep structures by Aichi prefecture. They are used to create 3D deep underground structure of Nobi plain.A seismic array is deployed near Yoro fault that places on the edge of Nobi plain. The records obtained by this array show that surface waves that would be excited on the edge of basement rock are observed, and interfered with direct wave around few kilometers apart from the edge, resulting amplification of seismic ground motion. Also, the same amplification is observed by FEM analysis using 2D structure of Nobi Plain. This amplification may cause the seismic damage band.The source model of Gifu-Ichinomiya line is investigated. The model that can explain the level cahange observed on Nobi earthquake is the fault with dip angle of 75 degree, rather than vertical fault that have been considered so far. The stress field estimated from source mechanism of aftershocks, however, shows no evidence for the occurrence of Gifu-Ichinomiya line.The area of disasters are re-surveyed and the highly damaged region is not band-shaped but wide area in Nobi plain. This result shows the damage is due to the characteristics of surface soil structures.

我们研究了1891年Nobi地震中观察到的地震破坏带的机制。取得了以下成果：分析了野比平原的大量地下构造资料，并与爱知县的深部构造调查结果进行了比较。在位于Nobi平原边缘的Yoro断层附近部署了地震台阵。该台阵获得的记录表明，观测到了在基底岩石边缘激发的表面波，并与距离边缘几公里左右的直达波发生干扰，导致地震地面运动放大。此外，通过使用Nobi Plain的2D结构的FEM分析观察到相同的放大。对岐阜一宫线的震源模型进行了研究。能够解释Nobi地震水平位移的模型是倾角为75度的断层，而不是迄今为止所认为的垂直断层。根据余震震源机制估计的应力场没有发现岐阜-一之宫线的存在。重新调查了受灾区域，发现严重受损区域不是带状的，而是野比平原的大面积区域。结果表明，这种破坏是由于表土结构的特性。