利用NLLoc方法对新疆精河地震的定位研究

Study on the Location of Jinghe Earthquakes in Xinjiang by Using the NLLoc Method

利用非线性定位方法NLLoc,对新疆精河地区2017年8月9日至9月30日期间M≥3.0级的22个地震进行重新定位,并与中国地震台网中心正式目录结果进行对比,讨论了NLLoc方法在速度模型复杂的新疆地区定位的可行性。研究结果表明,NLLoc方法重定位新疆精河地震事件中,在发震时刻、震中方面误差较小,满足定位精度要求,但深度值上相差较大。NLLoc方法定位结果相对较为集中,主要分布于14~21 km,与CAP反演的深度分布为12-21 km,平均深度17 km,主震的震源深度21 km结果相符合,且与新疆地区的平均震源深度21±10 km和北天山地震带的平均震源深度19 km的结论相符。结果显示:NLLoc方法可用于地壳速度结构变化大、分布复杂地区的新疆地震定位,且有助于更好地解决震源深度测定问题,提高地震定位精度。

By using the non-linear location method NLLoc,the paper relocates 22 earthquakes with M≥3.0 in the Jinghe area of Xinjiang from August 9th to September 30th,2017,compares them with the official catalog results of the China Earthquake Network Center,and discusses the feasibility of NLLoc method in Xinjiang region where the velocity model is complicated.The results show that the Jinghe earthquake events in Xinjiang relocated by using the NLLoc method has relatively small errors in the time of occurrence and epicenter,which meets the positioning accuracy requirements,but the depth value is quite different.The positioning results of the NLLoc method are relatively concentrated,which are mainly distributed during 14~21 km,and is consistent with the results obtained by the CAP inversion with a depth of 12~21 km,an average depth of 17 km,and a focal depth of 21 km of the main shock.It is also consistent with the conclusion that the average focal depth of the Xinjiang region is 21±10 km and the average focal depth of the northern Tianshan seismic belt is 19 km.In summary,the NLLoc method can be used to locate earthquakes in Xinjiang with large changes in crustal velocity structure and complex distribution,and it helps to better solve the problem of focal depth determination and improve the accuracy of earthquake positioning.