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 年野比地震中观测到的地震损伤带的机制。我们得到了以下成果：我们对浓尾平原的地下构造的大量数据进行了分析，并与爱知县深层构造的调查结果进行了汇总。它们用于创建浓尾平原的 3D 深层地下结构。地震台阵部署在浓尾平原边缘的养老断层附近。该台阵获得的记录显示，观测到在基岩边缘激发的面波，与距边缘几公里处的直达波发生干扰，导致地震动放大。此外，通过使用 Nobi Plain 的 2D 结构的 FEM 分析也观察到了相同的放大。这种放大可能会造成地震破坏带。对岐阜一宫线的震源模型进行了研究。能解释浓尾地震水平变化的模型是倾角为75°的断层，而不是目前所考虑的垂直断层。然而，根据余震震源机制推算的应力场，并没有显示岐阜一宫线发生的证据。对受灾面积进行重新勘察，发现浓尾平原的重灾区不是带状的，而是大面积的。这一结果表明损伤是由于表层土壤结构的特征造成的。