Study on the Precise Location of the Xinjiang Yutian Ms 7. 3 Earthquake

The seismic waveform of the Yutian MS7.3 earthquake,Xinjiang on February 12,2014 was recorded clearly and completely by the Digital Seismic Networks of Xinjiang,Qinghai,Tibet,and Xinjiang Hotan array,so the method of joint location by regional seismic network and seismic array can be used to accurately determine the earthquake source location.The following technologies were used in the process of location:(1) We selected seismic stations equally located around the epicenter of the MS7.3 earthquake with an average interval of about 15 degrees in the initial location.(2) The recording waveforms of Yutian seismic station were rotated to the radial and tangential directions to precisely obtain the arrival time of S-waves to determine the epicentral distance.(3) The velocity model was used in the determination of location of the epicenter,based on the historical records of earthquakes in the area within a radius of 1.0° from the source as the center,and the velocity model is obtained after re-fitting and calibration.(4) Based on the waveform records of the Hotan seismic array,the method of waveform beaming was used to determine the azimuths and perform the correction of the epicenter location with these azimuths.(5) The deterministic method was used to measure the source depth.Finally,it is concluded that the Yutian MS7.3 main shock hypocenter location is 36.197°N,82.467°E,focal depth 12 km and original time 17:19:48.2 p.m.February 12,2014.