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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

确定断裂带区段并评估单个区段边界阻止破裂传播的可靠性，对于准确估计活动断裂产生的未来地震的规模是至关重要的。破裂的传播方向与强烈的地面运动和由此造成的地震破坏密切相关。因此，预测地震破裂长度和方向性对减轻地震灾害至关重要。然而，它们大多是在地震后才从观测的地震学记录中确定的，而不是在地震之前确定的。本研究的目的是从活动断层的几何图形出发，提出一个活动断层的行为模型，以模拟与地表破裂有关的地震。Nakata和Goto(1998)提出了(1)活动断裂道的分支特征和(2)沿断裂道的垂直滑动分布特征等几何判据，作为预测未来地震破裂长度的工具。分支DUR…断层破裂传播被认为是一种有效的能量耗散过程，可能导致最终破裂终止，我们将这一概念模型命名为“形态单位模型”，并将按该模型分组的活动断层称为个别发震断层的“组合断层”。通过将这些新的几何准则应用于高分辨率活动断裂分布图，可以更实际地进行断层分组/分段。日本西南部岛根半岛的鹿岛断裂就是该模型最典型的例子之一。我们还在1943年鸟取地震的发震断层、日本中部地区的Chojagahara-Yoshii断裂带以及菲律宾吕宋岛北部的活动断裂系统上成功地检验了该模型。基于该模型，我们对日本的活动断裂进行了详细的潜在地震成因断层制图。将绘制的活动断层图数字化，并用于公共建筑和国家宝藏的地震危险性评估，基于数字化的活动断层数据估计活动断层产生的磁频率分布。根据本研究的结果，还利用四国中线活动断裂系统的地震参数模拟了强地面运动。较少