Earthquake Model based on Geometric Study of Active Fault

定义断裂带段和评估单个断裂带边界阻止传播破裂的可靠性对于准确估计未来由活动断层引起的地震的大小至关重要。断裂的传播方向与强地震动及其引起的地震破坏密切相关。因此，预测地震破裂长度和破裂指向性对减轻地震破坏至关重要。然而，它们大多是在地震后从观测到的地震记录中确定的，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模式，提出一个活动断层的行为模型，用于模拟与地表破裂有关的地震。Nakata和Goto（1998）提出了几何标准，如(1)活动断层线的分支特征和(2)沿断层线垂直滑动分布的特征模式，作为预测未来地震破裂长度的工具。断裂扩展过程中的分支被认为是一种有效的能量耗散过程，并可能导致断裂的最终终止。我们将这一概念模型命名为“形态计量单元模型”，并将按该模型分组的活动断层称为单个发震断层的“打包断层”。将这些新的几何准则应用到高分辨率活动断层分布图中，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裂是这一模式最典型的例子之一。我们还在引发1943年鸟取县地震的发震断层、日本Chugoku地区的Chojagahara-Yoshii断裂带以及菲律宾吕宋岛北部的活动断层系统上成功地测试了该模型。考虑到这一模型，我们对日本的活动断层作为潜在的发震断层进行了详细的测绘。将测绘的活动断层数字化，用于公共建筑和国宝的地震风险评估。基于数字化的活动断层数据，估计了活动断层产生的震级频率分布。根据研究结果分割的四国中构造线活动断裂系统的地震参数，模拟了强地震动。少

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