太原盆地2016年以来中小地震震源机制研究OA

[Purposes]On the basis of previous researches and the latest broadband digital wave-form data from the Shanxi Regional Seismic Network,multiple methods are employed to obtain up-dated focal mechanism solutions for earthquakes with ML≥2.5 that occurred in the Taiyuan basin be-tween May 2016 and December 2023.This work is carried out to further enrich the database of focal mechanism solutions for the Taiyuan basin and to provide reliable key foundational data and support for future scientific research and engineering practices in this region,including studies on earthquake preparation and occurrence mechanisms,seismic trend analyses,and disaster preventions.[Methods]According to the China Earthquake Networks Center(CENC),the focal mechanisms for 68 earth-quakes with magnitudes of 2.5 or above in the Taiyuan basin from May 2016 to December 2023 have been determined by using P-wave initial motion and CAP waveform inversion methods.[Results]The results indicate that the focal mechanisms of recent medium-small earthquakes in Taiyuan basin mainly belong to the normal strike mode,with some beloging to normal strike-slip or strike-slip mode,and few to thrust faulting mode.The directions of P-axis of each seismic source mechanism are mainly concentrated in the NEE-NE-NEN range,which shows the regional variation characteristics in the Taiyuan basin.Meanwhile,the directions of T-axis are concentrated in NW-NWN,showing obvious regional consistency.The results of the regional tectonic stress field with focal mechanism in-version show that the principal stress σ1-axis strikes 45°and the dip angle is 79°,and the principal as-sert σ3-axis strikes 149° and the dip angle is 3°,indicating that the Taiyuan basin as a whole is mainly under action of the horizontal stretching of NW and the vertical extrusion of NE,the principal stress axis shows certain changes in the plane.The above results also show that the tectonic stress field in this area has not changed significantly in recent years and has obvious inheritance.