Earthquake Model based on Geometric Study of Active Fault

定义断层带段和评估个别段边界的可靠性，以阻止传播破裂是必不可少的准确估计未来的地震规模产生的活动断层。破裂传播方向与强地面运动和地震破坏密切相关。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，它们大多是在地震发生后才从观测到的地震学记录中确定的，而不是在地震发生前确定的。Nakata和后藤（1998）提出了（1）活动断层痕迹的分支特征和（2）沿着断层痕迹的垂直滑动分布特征模式等几何判据，作为预测未来地震破裂长度的工具。分支过程 关于我们 断层破裂传播被认为是一个有效的能量耗散过程，并可能导致破裂的最终终止，我们将这一概念模型称为“形态单元模型”，并将按此模型分组的活动断层称为“成组断层”。将这些新的几何判据应用于高分辨率活断层分布图，可以更切合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。此外，还在1943年鸟取地震的发震断层、日本中国地区的Chojagahara-Yoshii断层带以及菲律宾吕宋岛北方的活动断层系统上成功地验证了该模型。将绘制的活断层数字化，用于公共建筑物和国家文物的地震危险性评估，并根据数字化的活断层数据估算活断层产生的震级-频度分布。根据本研究结果，以四国中央构造线活动断层系统的地震参数模拟强震。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