2012年6月24日宁蒗-盐源M_S5.7地震的精确定位

Accurate location of the June 24,2012 Ninglang-Yanyuan M_S5.7 earthquake

采用双差定位方法对2012年6月24日宁蒗-盐源MS5.7地震主震及其余震序列进行了重新定位.首先采用时间域互相关技术对波形数据进行处理,获得高精度的事件对走时差;然后分别使用目录数据、波形互相关数据和目录数据+波形互相关数据等3种不同的数据组合,对宁蒗-盐源MS5.7地震主震及其余震序列进行重新定位.3种数据组合的主震定位结果、参与重定位的地震事件数、最终被定位的地震事件数及重定位结果标准差等对比结果表明,同时使用目录数据和波形互相关数据所获得的重定位结果最佳.重定位结果显示,宁蒗-盐源MS5.7地震主震的震中位置为(27.790°N、100.707°E),震源深度为10.4km,发震时刻为北京时间2012年6月24日15时59分32.74秒.本文结果表明,震源区附近NW走向的永宁断裂为宁蒗-盐源MS5.7地震的发震构造.

This paper relocated the 24 June 2012 Ninglang-Yanyuan MS 5.7 earthquake and its aftershock sequence with double-difference earthquake loca-tion algorithm.Firstly,we used the cross-correlation technique in time domain to deal with waveform data and got high accuracy differential travel-time data of event pairs.And then we used three different data sets,which are catalog data,waveform cross-correlation data, and catalog data plus waveform cross-correlation data,as the initial data to relocate the Ninglang-Yanyuan earthquake sequence.Comparing the location of main shock,the number of events involved in relocation,the number of events relocated and relocation error for the three data sets,it is suggested that the relocation result of the third data set is the best.The result shows that the original time of the main shock is 15：59：32.74 （Beijing Time）on 24 June 2012,hypocenter location is （27.790＆#176;N,100.707＆#176;E）, and the focal depth is 10.4 km.Our research also shows that the nearby Yong-ning fault is the seismogenic structure of Ninglang-Yanyuan MS 5.7 earthquake sequence.