甘青交界地区sPn震相研究及其震源深度计算

STUDY ON THE s PN PHASE AND DEPTH OF EPICENTER IN THE JUNCTION AREA OF GANSU AND QINGHAI

通过对甘青交界地区3个M≥4.5级地震震相的分析,认为在震级M≥4.0级,震中距300km^800 km的甘青交界地区地震,青海数字地震台网部分台站可记录到清晰的sPn震相。采用sPnPn平均到时差方法计算2013年2月12日的青海海西5.1级地震震源深度为14.3 km、9月20日青海门源5.1级地震震源深度9.9 km;2014年10月25日甘肃碌曲4.5级地震震源深度15.2 km。为了验证上述计算结果,用CAP法反演上述3个地震矩心深度,误差比国家地震台网给出的震源深度均小于5km。进一步说明sPn-Pn平均到时差在甘青走时模型下,只要能识别出sPn震相,就能快速准确算出震源深度且震源深度误差较小,结果可靠。

The three phases of M≥4.5 earthquakes in the junction area of Gansu and Qinghai are analyzed. results show that the clear sPn seismic phase of M≥4.0 earthquakes in the junction area and their epicen- tral distances in 300 km to 800 km can be recorded by some digital seismic network stations in Qinghai Prov- ince. The depths of Qinghai Haixi M5. l earthquake on Feb. 12th ,2013 ,Qinghai Menyuan M 5.1 earthquake on Sept. 20th ,2013 and Gansu Luqu M4.5 earthquake on Oct. 25th,2014 are respectively 14.3 km,9.9 km and 15.2 km calculated by sPn - Pn average of the time difference method. By cap method to verify the above cal- culation results, the inversion of the above three earthquake depths, and the error of the results less than 5 km with the national seismic network, it is further illustrated that as long as it can identify the sPn seismic phase, the focal depth can be accurately calculate and the depth error is small, the result is reliable.