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Title:: Calculation of Focal Mechanism and Source Depth of Qinghai Menyuan M_S6.4 Earthquake in 2016

Author(s):: LI Qilei¹; LI Yuli¹; MA Li²; LUO Zihao²; 1. Earthquake Administration of Qinghai Province,Xining 810001,Qinghai,China2. Huangyuan Seismic Station,Earthquake Administration of Qinghai Province,Huangyuan 812100,Qinghai,China

Keywords:: Menyuan M_S6.4 earthquake; CAP method; focal mechanism; source depth; sPn phase

摘要:: 采用 CAP方法,反演了2016年1月21日门源M_S6.4地震震源机制,分析了震源机制解随震源深度的变化关系。计算结果显示,门源M_S6.4地震的发震断层是逆冲型断层,最佳矩心深度为11 km。为比较还反演了2013年9月20日门源5.1级地震的震源机制,两次地震的断层走向和倾角基本一致。为进一步验证震源深度计算结果的可靠性,利用滑动窗互相关技术提取sPn震相,通过计算sPn与Pn的到时差计算震源深度,得出的震源深度为15.2 km。校正深度震相法因震相识别精度和速度模型影响会产生10%～15%的误差后,结果与CAP方法比较接近。

Abstract:: By using the CAP(cut and paste)method,we inversed the focal mechanism solution of Menyuan M_S6.4 earthquake on Jan.21,2016,and analyzed its variation relationship with the source depth. The calculation results show that the seismogenic fault of the earthquake is a thrust type fault,and the optimum moment depth is 11 km. We also inverse the focal mechanism solution of Menyuan M_S5.1 earthquake on Sep.20,2013 and find that the strikes and dip angles of two Menyuan earthquakes are basically the same. In order to verify the reliability of the calculation results of the focal depth,we extract the sPn phase by the sliding window cross-correlation technology. Then we obtain the focal depth is 15.2 km by calculating the arrival time difference between sPn and Pn phases. However,because of the accuracy of phase identification and speed model of focal depth-phase method could induce the error of 10%～15%,the focal depth is close to the results calculated by the CAP method after correction.