首都圈地区中小地震全波形震源机制反演

doi:10.12196/j.issn.1000-3274.2020.04.001

摘要/Abstract

摘要： 目前对首都圈地区中小地震的震源机制研究所用的方法主要有P波初动极性法、振幅比法及波形反演方法。前两种方法只利用了波形中很少量的信息, 且对于稀疏台阵效果较差, 而传统的波形反演法也仅利用了波形的部分信息, 且对于震级、数据资料等有一定的要求。为克服上述传统方法中的局限并进一步提高震源机制解的准确性, 本文采用一种新的综合利用上述各种信息的全波形匹配方法来反演首都圈地区中小地震的震源机制解, 提高反演解的可靠性。为了检验所使用的全波形匹配震源机制反演方法的可靠性, 我们首先进行了合成数据测试, 结果表明全波形匹配方法可以得到稳定可靠的震源机制解。利用新的全波形匹配方法计算了2019年4月北京发生的两次地震震源机制解, 并结合活动断裂进行分析。将新的全波形震源机制反演方法应用于首都圈地区2015年以来的22个地震(2.2≤M≤4.3), 并对22个地震的震源机制解及应力轴分布进行了分析, 与前人研究结果具有较好的一致性。

关键词: 首都圈, 震源机制, 全波形匹配, 邻域算法

Abstract: Currently, the methods used in the study of the focal mechanism of small and moderate earthquakes in the capital region include the P-wave first motion polarity method, the amplitude ratio method and the waveform inversion method. The former two methods use only a small amount of information in the waveforms, and are limited by factors such as the station distribution, site effects etc. Similarly, the traditional waveform inversion method only uses part of the information of the waveform, and there are certain requirements for the magnitude and data quality, etc. To overcome the aforementioned limitations, this study attempts to use a new full waveform matching method, which uses comprehensive information mentioned above, to invert for the focal mechanism solution of earthquakes of small and moderate magnitude in the Capital Region, thereby improving the reliability of the solution. To test the reliability and applicability of the new full waveform matching method for the earthquakes in the capital region, we first perform a synthetic data test. The test results prove that the used full waveform matching method is stable and reliable. In early 2019, two recent M3+ earthquakes occurring in Beijing received extensive attention. We use the full waveform matching method to determine their focal mechanism solutions and analyze their occurrence in the background of regional active faults. Finally, we determine the focal mechanisms for 22 earthquakes (2.2≤M≤4.3) since 2015 in the capital region, and analyze the tectonic stress field in the capital region, which compares well with previous studies.

Key words: The capital region, Focal mechanism, Full waveform matching, Neighborhood algorithm

中图分类号:

P315.2

丁成, 李俊伦, 王晓山, 谭玉阳, 张海江. 首都圈地区中小地震全波形震源机制反演[J]. 地震, 2020, 40(4): 1-22.

DING Cheng, LI Jun-lun, WANG Xiao-shan, TAN Yu-yang, ZHANG Hai-jiang. Full-waveform Based Focal Mechanism Inversion for Earthquakes of Small and Moderate Magnitude in the Capital Region[J]. EARTHQUAKE, 2020, 40(4): 1-22.

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