1679年三河—平谷8级地震地表破裂端部特征及其地质意义

地震地表破裂端部的几何结构与运动学特征研究有助于科学认识断裂的破裂传播与终止过程。夏垫断裂是华北平原区最为重要的隐伏强震构造之一，于1679年发生了三河—平谷M8历史大地震，但其同震地表破裂长度及端部变形特征仍存争议。基于前人研究结果，在野外地质调查的基础上，跨1679年三河—平谷8级地震地表破裂端部布设了2条浅层地震勘探剖面，研究断裂端部的新活动特征。结果显示，断裂端部的最新活动时代为全新世，运动方式以走滑为主兼正断，且呈现出明显的滑动亏损特征。结合同震垂直位移分布等数据，分析认为该次地震的地表破裂仅长10余公里，与8级地震不匹配，其发震构造和机制仍需深入研究。

Characteristics of the surface rupture end of the 1679 Sanhe-Pinggu M8 earthquake and its geological significance

The research on the geometric structure and kinematic characteristics of the ends of earthquake surface ruptures is helpful to understand the fracture propagation and termination process scientifically. The Xiadian fault is a crucial seismogenic structure in the North China Plain, where occurred the Sanhe-Pinggu M8 earthquake in 1679. So far, the length of its co-seismic surface fracture and the deformation characteristics of its ending parts remains controversial. Based on the results of previous study and field geological survey, two shallow seismic exploration profiles were arranged at the end of the surface rupture of the 1679 Sanhe-Pinggu M8 earthquake, and the new activity characteristics at the end of the fault were studied. The results showed that the latest activity at the end of the fault occurred in the Holocene. The movement mode is mainly strike slip with a normal slip component, showing obvious characteristics of slip deficit. Combined with the data of co-seismic vertical displacement distribution, it is considered that the surface rupture of the earthquake is only more than 10 km long, which does not match the M8 earthquake, so the seismogenic structure and mechanism of the Sanhe-Pinggu M8 earthquake still need to be further studied.