2012年9月7日彝良地震及余震序列双差定位研究  

Double-difference relocation of the 7 September 2012 Yiliang earthquake and its aftershock sequence

作　　者：王清东[1] 朱良保[1,2] 苏有锦[3] 王光明[1] 

机构地区：[1]武汉大学测绘学院地球物理系,武汉430079 [2]武汉大学地球空间环境和大地测量重点实验室,武汉430079 [3]云南省地震局,昆明650224

出　　处：《地球物理学报》2015年第9期3205-3221,共17页Chinese Journal of Geophysics

基　　金：国家自然科学基金(41374053);国家测绘地理信息局测绘基础研究基金(13-02-06)资助

摘　　要：本文提出了时域多通道相关检测函数并用其计算波形互相关走时差数据,采用双差定位法对2012年9月7日云南彝良地震和余震序列共944个地震进行重定位,得到652个重定位事件,并与目录数据的结果进行了对比.本文采用了多个准则对走时差数据进行筛选,确保定位结果稳定可靠.得到MS5.7主震的震中为27.516°N,103.951°E,震源深度6.9km;MS5.6主震的震中为27.543°N,104.023°E,震源深度7.27km;重定位结果显示,地震序列紧缩为条带状并沿附近断裂走向分布,深度总体分布较重定位前变浅,集中分布在5～8km,地震群出现轻微倾斜.东西向、南北向、深度和发震时刻的平均相对误差分别为55.2 m,43.0 m,186.7 m和0.01s,走时残差16ms.研究表明：互相关数据的结果要优于目录数据;震源深度与速度模型存在较大的相关性;确定彝良—会泽断裂为本次彝良地震序列的发震构造。The object of this paper is to compare the relocation results between the catalog data and the cross-correlation data of the Yiliang earthquake sequence occurred in September 2011,then discuss the impact on the location of different velocity models and confirm the seismogenic fault structures.We adopted double difference algorithm for earthquake hypocenter relocation by using catalog data and cross-correlation data respectively.We proposed the time domain multi-channel correlation detection function and used it to calculate waveform cross-correlation travel time difference data.In general,the number of the waveform cross-correlation data is less than the catalog data,so the number of relocation earthquakes is small.In order to overcome this shortcoming,we used the catalog data to supplement the waveform cross-correlation data and set the weight of catalog data less than the waveform cross-correlation data.To ensure that the relocation results were stable and reliable,we used multiple criteria to filter the travel time difference data.The proportion of two kinds of data was about 17.5∶1in our cross-correlation data used in relocation.In order to find the most suitable velocity model for the regional crust structure and ensure the relocation results were reliable,we used four velocity models and chose the best results.Among the 944 ML≥1.0earthquakes of Yiliang earthquake sequence from September 7to October 7,2012,we obtained 652 relocation events.The location of MS5.7main earthquake was27.516°N,103.951°E,and 6.9km in the depth.The location of MS5.6 main earthquake was27.543°N,104.023°E,and 7.27 km in the depth.The Yiliang earthquake sequence was located between Zhaotong-Ludian fault and Yiliang-Huize fault which were both NE trending,and the two main earthquakes occurred at opposite ends of the sequence.Relocation results show that the earthquake sequence was more concentrated along the nearby fault,the seismic strip extended for less than 20 km,the depth distribution became shallower than before and was ma

关 键 词：彝良地震 双差定位 波形互相关 彝良—会泽断裂 

分 类 号：P315[天文地球—地震学]