Establishment of a zoning method for fault bedrocks based on the strain partitioning of multiple faults and seismic properties of fault rocks

基于多断层应变分区和断层岩地震特性的断层基岩分区方法的建立

基本信息

批准号：
16310127
负责人：
KANAORI Yuji
金额：
$ 9.64万
依托单位：
Yamaguchi University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2007
项目状态：
已结题

项目摘要

NE-SW-trending, 105-km long Lake Ohara -W. Yauneyama fault system (OYFS) is developed in western Chugoku District. This fault system is composed of multiple faults. The Yamaguchi -Izumo seismic zone exists along the OYFS. The movement of active faults may be related to a formational mechanism of these basins, because the basins are located at bending parts of the faults. On the other hand, in this study, bedrocks which are affected by a fault movement and are in the vicinity of a fault are defined as "fault bedrock".In order to obtain a basic data for mitigating bedrock disaster caused by inland earthquakes, this study establishes a zoning method of seismic hazards for the fault bedrock. We select the OYFS as a case study, and the contents of the investigation and results are as follows.1. Configuration of in plane view of the constituent fault of the OYFS is revealed, and strain partitioning of each constituent fault is analyzed by a combination microscopic observations of fault rocks and fault process zones.2. Velocities, Vp and Vs, of the fault rock and the process zone are measured on rock samples in a laboratory and on outcrops in situ, respectively, and seismic properties of the fault bedrock are obtained. By combining the seismic property with the microscopic observation of the fault rock, a classification criterion of the fault bedrock is developed. Based on the classification criterion, a classification map of fault rocks is made up in the area along the OYFS.3. Three-dimensional configuration of the multiple fault system is reconstructed by the combination of regional geology information, geophysical data and the result (1).4. Using a two-dimensional finite element method, fault movement is simulated on the reconstructed model of the multiple fault system, and the seismic risk is evaluated.

东北-西南走向，长105公里的大原湖-西。田根山断层系（OYFS）发育于中国地区西部。该断层系统由多个断层组成。山口-出云地震带沿 OYFS 存在。活动断层的运动可能与这些盆地的形成机制有关，因为盆地位于断层的弯曲部分。另一方面，本研究将受断层运动影响且位于断层附近的基岩定义为“断层基岩”。为了获得减轻内陆地震引起的基岩灾害的基础数据，研究建立了断层基岩地震危险性分区方法。我们选取OYFS作为案例研究，调查内容及结果如下： 1．结合断层岩石和断裂过程带的显微观察，揭示了OYFS组成断层的平面构型，并分析了各组成断层的应变分配。 2．分别在实验室岩石样本和现场露头上测量断层岩石和加工带的速度Vp和Vs，并获得断层基岩的地震特性。将地震特性与断层岩的微观观察相结合，建立了断层基岩的分类标准。根据分类标准，绘制了OYFS沿线地区断层岩分类图。3．结合区域地质信息、地球物理数据和结果(1)，重建了多断裂系统的三维构型。4．利用二维有限元方法，在多断层系统重建模型上模拟断层运动，并评估地震风险。