EARTHQUAKE LOCATION METHOD WITH ARRIVAL TIME UNCERTAINTY CONSIDERED AND ITS APPLICATION TO LOCATION OF EARTHQUAKES FROM 2001 TO 2008 IN SICHUAN AREA

doi:10.3969/j.issn.0253-4967.2012.01.001

Abstract

Abstract:

The precisely located earthquake catalogue is important to seismicity, seismic tomography and crustal stress inversion studies. It also has great application value in rapid report of an earthquake that just occurred. By considering the arrival time uncertainty, and the constraints on station elevation and seismic depth, we propose a relatively accurate method to estimate hypocentral location and its uncertainty based on inversion theory. Our method can combine the arrival times of Pg wave, Sg wave, Pn wave and Sn wave in hypocenter location, so it increases the location accuracy by involving more data; and it can be also used in local and regional earthquake location simultaneously. In order to test our location method, we located earthquakes by using the simulated data with different uncertainty of Pg,Sg,Pn,Sn arrivals. The result shows that the location determined by using our method is more accurate than that by using other method. We apply it to earthquakes occurring in the period from 2001 to 2008 in Sichuan area, and obtained a more clustered hypocentral distribution convergent to the fault zones. The result provides a solid foundation for studies of seismicity, geometry of the active faults and seismic tomography in Sichuan region. It is also helpful to study the seismicity precursors before the Wenchuan earthquake.

Key words: earthquake location, uncertainty, station elevation, Sichuan area

摘要：

精确的地震位置对于地震活动性、地震层析成像和地壳应力场反演具有相当重要的意义,对于地震速报也具有重要的应用价值。将观测到时的不确定性、台站高程、地震震源深度进行约束的同时,根据反演理论给出了地震震源位置精确估计和误差估计的方法。该算法联合考虑Pg波、Sg波、Pn波和Sn波的到时进行反演,数据量的增加可以增强地震位置的准确性,并可同时应用于地方震和区域地震。采用模拟数据对该地震定位算法进行检验发现,该算法在观测数据的不确定性不等时明显优于其他方法。将该算法应用于四川地区2001-2008年间的地震定位,得到的地震位置更加符合地震的丛集性并集中于断裂带附近。这些结果为四川地区的地震活动性、断层构造以及地震层析成像研究打下了基础,并且为汶川地震之前的地震活动前兆研究也提供了有益帮助。

关键词: 地震定位, 不确定性, 台站高程, 四川地区

CLC Number:

P315.5

WAN Yong-ge, SHENG Shu-zhong, CHENG Wan-zheng, ZHANG Zhi-wei, WU Ye, ZHAO Xiao-yan, BU Yu-fei, XUE Zhi-fang, LIU Jin-li. EARTHQUAKE LOCATION METHOD WITH ARRIVAL TIME UNCERTAINTY CONSIDERED AND ITS APPLICATION TO LOCATION OF EARTHQUAKES FROM 2001 TO 2008 IN SICHUAN AREA[J]. SEISMOLOGY AND GEOLOGY, 2012, 34(1): 1-10.

万永革, 盛书中, 程万正, 张致伟, 武晔, 赵晓燕, 卜玉菲, 薛志芳, 刘金丽. 考虑到时误差的地震定位算法及其在四川地区2001-2008年地震定位的应用[J]. 地震地质, 2012, 34(1): 1-10.

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