2013年甘肃岷县漳县M_S6.6地震及其余震序列重定位  

Relocation of Mainshock and Aftershocks of the 2013 Minxian-Zhangxian M_S6.6 Earthquake in Gansu

作　　者：冯红武[1] 张元生[1,2] 刘旭宙[1,2] 陈继锋[1] 姚海东[1] 张璇[1] 

机构地区：[1]中国地震局兰州地震研究所,甘肃兰州730000 [2]中国地震局地震预测研究所兰州创新基地,甘肃兰州730000

出　　处：《地震工程学报》2013年第3期443-447,共5页China Earthquake Engineering Journal

基　　金：中国地震局兰州地震研究所地震科技发展基金野外站基金(2013Y01);国家自然科学基金项目(40874029)

摘　　要：使用甘东南地区三维速度模型,利用三维网格搜索法和双差地震定位法对2013年7月22日甘肃岷县漳县MS6.6地震及其震后三天的余震序列进行了精确定位,结合地质构造资料对本次地震的发震构造进行了初步研究。其结果显示:主震的震中位置为34.54°N,104.189°E,震源深度13.5km;余震震中呈NW或NWW方向分布,与临潭-宕昌断裂的走向基本吻合,主要分布于5～20km的深度,震中在深度剖面上呈SW向;发震断裂为倾向SW的隐伏断层,位于临潭-宕昌断裂NE方向,距临潭-宕昌断裂约20km。A 3-D velocity model of the southeast Gansu Province region, including the 3-D grid searching algorithm and double difference method, was used to examine the relocation the Minx- ian--Zhangxian Ms6.6 earthquake occurring on July 22, 2013, and its aftershocks from July 22 to July 25. The grid search method was used to determine earthquake location and the S--P arrival time of 400 seismic events, which agreed with data detected by at least three stations. Of these e- vents, 336 were used to calculate double-difference location, and 261 were used to obtain the relo- cation results. After relocation, the average estimation errors of the source location were 1498 m in the E--W direction, 1385.2 m in the N--S direction, and 2 492.3 m in the vertical direction. On the basis of these calculation results, the seism0genic structure was compared with the data of geological structure, and the results showed that the mainshock was relocated to 34.54°N, 104. 189°E, with a focal depth of 13.5 km. The aftershocks were distributed mainly between the Lint- an--Tanchang fault and the northern edge of the West Qinling fault; several were distributed in the southwestern region of the Lintan fault. The distribution of the aftershocks was in the NW or NWW direction, which is essentially consistent with the strike of Lintan--Tanchang fault, al- though the dominant distribution was not obvious. Therefore, we examined the A--Ar profileperpendicular to the direction to research the relationship between the distribution of earthquakes and fracture structure and determined that this profile crosscuts the Lintan--Tanchang fault. We obtained similar results using the 3-D grid searching algorithm and the double difference method, which revealed that the focus depths are mainly distributed in 0~10 km before relocation, and the average depth was 6 km. In contrast, the focus depths of the aftershocks were distributed mainly in 5~20 km after relocation, which indicates that the aftershock sequence occurred mainly in the upper and lower crust. The

关 键 词：岷县漳县地震 地震定位 发震断裂 余震序列 

分 类 号：P316.63[天文地球—地震学]