邢台震区应力场特征及M_(L)3.5以上地震的发震背景分析  

Analysis of the Stress Field Characteristics in the Xingtai Seismic Region and the Seismogenic Background of Earthquakes with Magnitudes above M_(L)3.5

作　　者：章阳 董博 王时[1,2] ZHANG Yang;DONG Bo;WANG Shi(Hebei Hongshan Thick Sediment and Earthquake Disaster National Field Scientific Observation and Research Station,Xingtai,Hebei 054000,China;Hebei Earthquake Agency,Shijiazhuang,Hebei 050021,China)

机构地区：[1]河北红山巨厚沉积与地震灾害国家野外科学观测研究站,河北邢台054000 [2]河北省地震局,河北石家庄050021

出　　处：《山西地震》2024年第1期5-9,56,共6页Earthquake Research in Shanxi

基　　金：河北省地震科技星火计划(DZ2021121400006,DZ2023120600003)资助。

摘　　要：邢台老震区构造背景复杂,发育多组断裂,属构造较不稳定地带,且区域中小地震频发。2017年至2021年发生6次M_(L)3.5以上地震,其中有两次M L4以上地震。本文基于搜集的震源机制解资料,反演区域现今地壳应力场,模拟震源机制与地壳应力场的关系,计算地壳应力场在地震发震断层面上的相对剪应力和相对正应力,分析地震的发震背景。结果表明,6次M_(L)3.5以上地震中,有2次震源机制节面接近应力场的最大剪应力节面,有4次震源机制节面远离应力场的最大剪应力节面。说明地震不是完全按照震源机制节面上具有最大剪应力的破裂方向发生,有时可能发生在某些薄弱带上。因此,在进行地震预测时,不能只关注最大剪应力破裂方向,还应多关注其边缘的地质薄弱带,这一结果可能会为后续分析该区域的地震危险性,研究地震孕育机制及动力学过程提供一定的参考依据。The old seismic area of Xingtai has a complex tectonic background,with multiple sets of faults developed,belonging to a relatively unstable tectonic zone with frequent regional minor and moderate earthquakes.From 2017 to 2021,there were six earthquakes above M_(L)3.5,including two above M L4.Based on collected focal mechanism solution data,this paper inverts the current crustal stress field in the region,simulates the relationship between the focal mechanism and the crustal stress field,and calculates the relative shear stress and normal stress on the seismogenic fault plane of the crustal stress field,analyzing the seismogenic background of the earthquakes.The results show that among the six earthquakes above M_(L)3.5,the focal mechanism planes of two earthquakes are close to the plane of maximum shear stress in the stress field,while the planes of four earthquakes are far from the plane of maximum shear stress.This indicates that earthquakes do not always occur in the direction of maximum shear stress on the focal mechanism planes,and sometimes may occur in some weak zones.Therefore,in earthquake prediction,it is not sufficient to only focus on the direction of maximum shear stress rupture;attention should also be paid to the geological weak zones at the edges.This result may provide a reference for subsequent analysis of the seismic risk in the region and for studying the seismogenic mechanism and dynamic process.

关 键 词：应力场 邢台震区 破裂方向 发震背景 地质薄弱带 

分 类 号：P315.2[天文地球—地震学]