2019年1月12日新疆疏附5.1级地震序列重定位及发震构造研究

doi:10.12196/j.issn.1000-3274.2020.01.004

摘要/Abstract

摘要： 基于新疆区域数字地震台网震相观测报告, 采用双差定位方法对2019年新疆疏附M_S5.1地震序列M_L≥1.0地震进行重定位, 采用CAP波形反演方法, 获得了主震的震源机制解和震源矩心深度, 进而综合分析了本次地震可能的发震构造。结果表明, 疏附5.1级地震震源位置为39.59°N, 75.57°E, 初始破裂深度为18 km, 震源矩心深度为18 km。重定位后的地震序列呈两个优势方向展布, 分别为NEE向和NE向分支, NEE向为主要的余震优势分布区域, 呈长约13 km窄带状分布在喀什断裂附近。另一条优势分布为沿NE向长度约9 km, 这可能与喀什断裂阶区有关。深度剖面显示, 地震震源深度主要集中分布在8~20 km。沿NEE走向深度剖面显示, 疏附5.1级地震破裂于深部, 余震沿优势分布的震源深度自SWW向NEE呈现逐渐加深的变化特征。垂直于震中优势分布的深度剖面显示, 本次地震发震断层面倾向为N倾。震源机制解显示本次地震断错类型为逆冲型, 结合震源深度剖面特征推断节面Ⅰ为本次地震的发震断层面。综合地震序列空间分布特征、震源机制以及震源区地质资料, 推测此次地震的发震构造可能为喀什断裂, 余震向浅部扩展。

关键词: 疏附5.1级地震, 双差定位方法, 震源机制, 发震构造, 喀什断裂

Abstract: Based on the digital waveforms of Xinjiang Seismic Network, The Shufu M_S5.1 earthquake sequence (M_L≥1.0) was relocated precisely by HypoDD. The best double-couple focal mechanisms of the main shock was determined by the CAP method. We analyzed the seismogenic structure of earthquake sequences.The results show that the main shock was relocated at 39.59°N, 75.57°E, the depth of the initial rupture and centriod is about 18.2 km and 18 km. The distribution of aftershocks presents an asymmetric conjugate shape in NEE and NE directions. The NEE is the main rupture distribution of the aftershocks with length of about 13 km which is closed to the Kashi fault. Another advantage is that the NE is about 9 km which may be related to the Kashi faults step.The characteristics of the depth profiles show that the focal depth of the earthquake were mainly located in the depth of 8~20 km. The depth profile of the NEE shows that the Shufu 5.1 earthquake ruptured to the depth and tended to be deeper. The depth profile perpendicular to the Kashi fault shows that the fault plane was dipping north. It showed that the focal mechanism of the main shock was thrust. The dip of nodal plane Ⅱ is consist with the dip of the depth profile, which is inferred from the seismogenic nodal. According to the precise positioning results derived, the focal mechanism and geological structure in the source region, a comprehensive analysis of the M_S5.1 earthquake seismogenic structure may be Kashi fault, and the aftershocks extend to shallow.

Key words: Shufu M_S5.1 earthquake, HypoDD location, focal mechanism, seismogenic structure, Kashi fault

中图分类号:

P315.7

刘建明, 李金, 姚远, 聂晓红, 滕海涛. 2019年1月12日新疆疏附5.1级地震序列重定位及发震构造研究[J]. 地震, 2020, 40(1): 52-61.

LIU Jian-ming, LI Jin, YAO Yuan, NIE Xiao-hong, TENG Hai-tao. Relocation of the Shufu M_S5.1 Earthquake Sequence on 12 January 2019 and Analysis of the Seismogenic Structure[J]. EARTHQUAKE, 2020, 40(1): 52-61.

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