龙门山断裂带周缘重复地震识别及其在台网定位评价中的应用

Repeating earthquakes have been used in assessing the location accuracy of the seismograph network for more than a decade. In this study, we used the continuous waveform data recorded by the State Earthquake Information Service Digital Media Center (SEIS DMC) between August 2007 and December 2014 to search for repeating earthquakes along the Longmenshan fault zone (LMSFZ). We obtained 2790 repeating earthquakes by using cross-correlation analysis of waveform data, based on the principle that repeating events should be recorded by at least 3 stations and have a cross-correlation coefficient C>0.8. With the assumption that the repeating events were separated by no more than 1 km, the location difference of repeating earthquakes recorded by seismic catalogue is mainly caused by the positioning error of seismic network. Based on this error, weestimate the positioning accuaracy of seismic network around Longmenshan fault zone. It is observed that the "horizontal location error" of seismograph network near LMSFZ is estimated to be below 5 km, with an average of 2.8 km. And the average location accuracy of the southwestern segment of the LMSFZ is better than that of the central-northern segment. The results also show that the "vertical location error" is estimated to be about 10 km.