Analysis of the Stress Field Characteristics in the Xingtai Seismic Region and the Seismogenic Background of Earthquakes with Magnitudes above ML3.5
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 earth-quakes above ML3.5,including two above ML4.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 back-ground of the earthquakes.The results show that among the six earthquakes above ML3.5,the focal mechanism planes of two earth-quakes 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 fo-cus 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.
stress fieldXingtai seismic arearupture directionseismogenic backgroundgeological weak zones
万方数据
