Abstract:After the Yutian, Xinjiang earthquake of MS7.3 that occurred on February 12, 2014, the Mongolia earthquake of MS4.9 and Hami, Xinjiang earthquake of MS5.1 occurred on the western margin of the Alax block. This shows that seismic activity is strengthening on the western margin of the Alax block. The cut-and-paste(CAP) method performs inversion of the entire profile of an earthquake, the result of which has advantages of relatively small merit that rely on the modeling of speed and lateral movement of the earth's crust. Its basic principle is splitting seismic broadband waveform data into Pnl wave and surface-wave parts, calculating the objective error function of the observed and theoretical seismograms, performing a grid search in the assigned parameter space, and searching for the focal mechanism and focal(centroid) depth using the two global minimum variances. In this study, using wave data from the Digital Seismological Network of Gansu Province and adopting the CAP method, we determined the focal mechanisms of the two earthquakes. The result shows that the focal mechanisms of the Mongolia MS4.9 and Hami, Xinjiang MS5.1 earthquakes were strike-slip and thrust, respectively.Our analysis concludes that the occurrence of the Mongolia MS4.9 and Hami, Xinjiang MS5.1 earthquakes exhibits a correlation with the interaction of the Qinghai-Tibet block and the Alax block.
