2018年9月12日19时6分,陕西省汉中市宁强县发生5.3级地震,不同机构给出的震源深度结果相差较大。为进一步确定宁强5.3级地震的震源深度,基于区域速度模型,首先利用CAP方法反演得到该地震的震源机制解,然后采用瑞利面波振幅谱和CAP深度误差函数联合反演,进一步测定了此次地震的矩心深度。结果显示:CAP方法得到的陕西宁强5.3级地震矩心深度约为12km,瑞利面波振幅谱测定的矩心深度为13km,结合引入的误差函数联合反演,最终确定陕西宁强5.3级地震的矩心深度为13km左右,表明此次地震仍属于发生于上地壳的地震。

At 19:06 on September 12,2018,an M_S5.3 earthquake occurred in Ningqiang county,Hanzhong city,Shaanxi Province. The earthquake depth given by different institutions are somewhat different. Based on the regional velocity model,the focal depth of this earthquake is calculated in this paper in order to confirm the depth result. Firstly,the focal mechanism solution of the earthquake is obtained by inversion by using the CAP method,and then the focal depth is further determined by using the Rayleigh surface wave amplitude spectrum and the error function of the CAP method. The calculation results show that the focal depth of the Ningqiang M_S5.3 earthquake obtained by the CAP method is about 12km,while that of the Rayleigh surface wave amplitude spectrum is 13km. Combining with the above two methods,it is finally determined that the focal depth of the Ningqiang M_S5.3 earthquake is about 13km,which indicates that this earthquake occurred at the upper crust.

国家自然科学基金(42004048)、中国地震局地震预测开放基金(XH23079D)共同资助