2020年唐山古冶M5.1地震震源区小震震源机制和应力场的求解

doi:10.12196/j.issn.1000-3274.2025.01.001

摘要/Abstract

摘要： 2020年7月12日唐山古冶发生M5.1地震, 为研究该地震发生处的应力状态, 我们利用震后布设的密集台阵观测资料和区域固定台网观测资料识别出20505个P波初动符号, 得到96个震源机制解和该地区0.25°×0.25°的精细地壳应力场。结果表明, 唐山古冶地震震源区小震震源机制以走滑型为主, 其次是正断型; P轴走向为NNE向, 多数倾伏角偏大, T轴走向为NNW向, 倾伏角偏小。而且我们发现, 在滦县—乐亭断裂附近地区的P轴方位存在一定角度的偏转, 即由该断裂西侧的NEE—SWW向偏转为断裂东侧的NW—SE向, 表明该断裂带的逆冲走滑活动分隔了其两侧的应力场。本文通过对小震震源机制和应力场的求解和分析, 为该地区特别是滦县—乐亭断裂附近地区的地震环境进一步研究提供参考。

关键词: 综合震源机制解, 应力场, P波初动, 密集台阵

Abstract: In order to study the stress state at the source region of the M5.1 earthquake occurred on July 12, 2020, a dense array was deployed in this area after the earthquake. 96 focal mechanism solutions and a fine crustal stress field of 0.25°×0.25° were obtained by using 20505 P-wave first motion polarity data in the earthquake source region and its adjacent area. The results show that: The focal mechanism of small earthquakes in the Guye earthquake region of Tangshan is mainly strike-slip type, followed by normal-fault type. The P-axis is NNE oriented with large of the plunge angle, while the T-axis NNW oriented with smaller plunge angle. Moreover, we found that there is a certain angle of deflection in the P-axis azimuth in the area near the Luanxian-Laoting fault, that is, from the NEE—SWW oriented deflection on the west side of the fault to the NW—SE oriented deflection on the east side of the fault, indicating the division of the stress field by the reverse-normal activity of the Luanxian-Laoting fault. The solution and analysis of the focal mechanism and stress field of small earthquakes can provide reference for further research in this area, especially in the area near the Luanxian-Laoting fault.

Key words: Comprehensive focal mechanism solution, Stress field, P wave initial motion, Dense array

中图分类号:

P315.2

严少鹏, 万永革. 2020年唐山古冶M5.1地震震源区小震震源机制和应力场的求解[J]. 地震, 2025, 45(1): 1-15.

YAN Shao-peng, WAN Yong-ge. Solution of Focal Mechanism and Stress Field by Small Earthquakes Data in Source Region of the Guye, Tangshan, M5.1 Earthquake in 2020[J]. EARTHQUAKE, 2025, 45(1): 1-15.

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