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Earthquake Model based on Geometric Study of Active Fault

基于活断层几何研究的地震模型

基本信息

批准号：
14380032
负责人：
NAKATA Takashi
金额：
$ 3.84万
依托单位：
HIROSHIMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14380032/
关键词：
active fault directivity effect segmentation fault branching fault rupture process strong motion simulation

项目摘要

Defining fault-zone segments and evaluating the reliability of individual segment boundaries to stop propagating ruptures are essential for accurate size estimation of future earthquakes generated from active faults. Direction of rupture propagation is closely related to strong ground motions and resulting earthquake damage. Therefore, predicting earthquake rupture length and directivity are crucial in mitigating earthquake damage. However, they were mostly ascertained only after earthquakes from the observed seismological records and not before the earthquakes.The purpose of this study is to propose a behavioral model of active faults from their geometric pattern for simulating earthquakes associated with surface ruptures. Nakata and Goto (1998) proposed the geometric criteria such as (1)branching features of active fault traces and (2)characteristic pattern of vertical-slip distribution along the fault traces as tools to predict rupture length of future earthquakes. The branching dur … More ing the fault rupture propagation is regarded as an effective energy dissipation process and could result in final rupture termination.We name this conceptual model as "Morphometric Unit Model" and call active faults grouped by the model as "Packaged Faults" for individual seismogenic faults. By applying these new geometric criteria to the high-resolution active fault distribution maps, the fault grouping/segmentation could be more practically conducted. Kashima fault in Shimane Peninsula, SW Japan is revealed as one of the most typical examples for this model. We also tested this model successfully on the seismogenic fault that generated the 1943 Tottori earthquake, the Chojagahara-Yoshii fault zone in Chugoku district in Japan, as well as the active fault system in northern Luzon, the Philippines.With this model in mind, we conducted detailed mapping of active faults in Japan as potential seimogenic faults. The active faults mapped were digitized, and used for seismic risk assessment for public buildings and national treasures.Magnitude-frequency distribution generated from the active faults was estimated based on the digitized active faults data. Strong ground motion was also simulated from the parameter of the earthquakes from the active fault system of the Median Tectonic Line in Shikoku segmented following the result of this study. Less

定义断层带段并评估各个断层边界的可靠性以阻止破裂传播对于准确估计活动断层未来产生的地震的规模至关重要。破裂扩展的方向与强烈的地面运动和由此产生的地震破坏密切相关。因此，预测地震破裂长度和方向性对于减轻地震损害至关重要。然而，它们大多是在地震后根据观测到的地震记录而不是在地震前确定的。本研究的目的是根据活动断层的几何图案提出一种活动断层的行为模型，用于模拟与地表破裂相关的地震。 Nakata和Goto（1998）提出了几何标准，例如（1）活动断层迹的分支特征和（2）沿断层迹的垂直滑移分布的特征模式，作为预测未来地震破裂长度的工具。断层破裂传播过程中的分支被视为有效的能量耗散过程，可能导致最终破裂终止。我们将这个概念模型命名为“形态单元模型”，并将该模型分组的活动断层称为单个发震断层的“打包断层”。通过将这些新的几何标准应用于高分辨率活动断层分布图，可以更实际地进行断层分组/分割。日本西南部岛根半岛的鹿岛断层是该模型最典型的例子之一。我们还在引发1943年鸟取地震的发震断层、日本中国地区的长者原-吉井断裂带以及菲律宾吕宋岛北部的活动断层系统上成功测试了该模型。根据该模型，我们对日本的活动断层作为潜在的发震断层进行了详细测绘。将活动断层图数字化，用于公共建筑和国宝的地震风险评估。根据数字化的活动断层数据估计活动断层产生的震级频率分布。根据本研究的结果，还根据四国中线构造线活动断层系统的地震参数模拟了强烈的地面运动。较少的