2018年云南通海2次M_(S)5.0地震震源机制解及深度测定  

Focal Mechanism and Focal Depth Determination of the Two Tonghai,Yunnan,M_(S)5.0 Earthquakes in 2018

作　　者：李姣[1] 姜金钟[1] 王光明 付虹[1] LI Jiao;JIANG Jinzhong;WANG Guangming;FU Hong(Yunnan Earthquake Agency,Kunming 650224,Yunnan,China)

机构地区：[1]云南省地震局,云南昆明650224

出　　处：《地震研究》2021年第2期133-144,共12页Journal of Seismological Research

基　　金：云南省地震局科技专项基金(2018ZX01);云南省地震局“地震机理与孕震环境研究”创新团队;云南省科技计划项目基础研究青年项目(2018FD158)联合资助。

摘　　要：准确的震源机制解和震源深度是深入理解地震发震机理的基础。针对2018年8月13、14日在云南通海发生的2次M_(S)5.0地震,利用云南地震台网30多个宽频带地震仪的波形记录,采用3个不同的区域速度模型和CAP方法获得了2次地震的震源机制解及矩心深度,并选取方位角约为300°的不同震中距的多个台站记录到的sPn深度震相准确测定了2次地震的初始破裂深度。结果表明:(1)基于数量更多、方位角覆盖较好的近台宽频带地震波形,在不同频率域内利用3个速度模型反演得到了2次地震的矩心深度分别为8 km和7 km;(2)利用震中距大于260 km、方位角约300°的多个地震台记录波形的sPn和Pn震相的到时差,测定2次地震的初始破裂深度约为10 km, 2种深度的差异可能是反映了主震沿断层面自下向上扩展的破裂过程;(3)结合双差重定位及CAP反演结果,初步认为2次M_(S)5.0地震的震源机制解应该是一致的,2018年2次通海M_(S)5.0地震的发震断层应该为同一条左旋走滑型断层,其断层面走向/倾角/滑动角约为20°/75°/-10°。Accurate earthquake parameters(e.g.focal mechanism and depth)are crucial for understanding the seismogenic mechanism.Based on waveforms of the 2018 Tonghai, Yunnan, M_(S)5.0 earthquakes recorded by more than 30 broadband seismic stations of the Yunnan Earthquake Networks, we invert their focal mechanisms and depths by using Cut-and-Paste(CAP)method and three different regional velocity models.We also employ sPn depth-phases recorded by different stations situated at the azimuth of ~300° to estimate the focal depth of the Tonghai M_(S)5.0 double earthquakes.The results are as follows:(1) Based on more broadband waveforms of near-earthquakes with better azimuth coverage, the obtained centroid depths(8 km and 7 km)of the two earthquakes inverted from different velocity models and frequency bands are more reliable.(2) By using sPn depth-phases at different stations with similar azimuth(~300°),we determine that the initial rupture depth of the two earthquakes are both about 10 km, which may indicate the rupture directivity(from bottom to top)of the earthquakes.(3) According to the Double-difference relocation and our CAP inversions, we preliminarily infer that the Tonghai double earthquakes should occur on the same fault plane, whose parameters, strike/dip/rake, could be 20°/75°/-10°.

关 键 词：通海地震 CAP方法 sPn深度震相 震源机制解 震源深度 

分 类 号：P315.33[天文地球—地震学]