天山东北部地震的重新定位和一维地壳速度模型的改善

Relocation of earthquakes in the northeastern Tianshan Mountains area and improvement of local 1-Dimensional crustal velocity model

根据布设在乌鲁木齐市活断层探测区内的流动宽频带地震台阵,结合区域地震台网的走时数据,利用3种不同的定位方法对新疆天山东北部地区(E85°30'～88°30',N43°00'～44°40')2004年8月至2005年8月发生的599个地震进行了重新定位。通过比较不同方法的结果合理性,确定了适合于当地震源精定位的程序,并改善了一维地壳速度模型。结果表明:联合使用流动地震台阵和区域台网的资料,显著提高了研究区的地震定位能力,精定位后震中分布图像更加集中,展示出了天山东北部地区更为明显的与活动构造相关的条带状地震活动分布图像,除了一些与已知断层相关的地震事件外,还发现一些有待证实的活断层。

We apply three methods to relocate 599 earthquake events occurring from August 2004 to August 2005 in the northeastern Tianshan Mountains area （85°30′~88°30′E, 43°00′~44°40′N）by using travel times recorded by regional seismic network and 10 portable seismic stations deployed around Urumqi. By comparing the reliability of different results, we determined a suitable location method, and an improved 1-Dimensional crustal velocity model of study area. The uncertainty of earthquake location is significantly reduced with combine data of seismic network and portable stations. The relocated events are clearly associated with regional tectonics of the northeastern Tianshan Mountains area, and are also in agreement with the existence of active faults imaged by deep seismic reflection profiling. The relocated seismicity also demonstrates that some potential traces of buried active faults need to be further validated.