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2020年云南巧家MS5.0地震微震检测及发震构造初步探讨
徐志国1,2, 梁姗姗3, 刘敬光3, 翟璐媛3, 史健宇1, 周元泽2
1.国家海洋环境预报中心, 北京 100081;2.中国科学院大学, 地球与行星科学学院, 北京 100049;3.中国地震台网中心, 北京 100045
摘要:
利用匹配定位方法对2020年5月18日云南巧家MS5.0地震震后24h震源附近台站记录的连续波形进行遗漏地震扫描和定位,共识别出327个地震事件,约为台网目录的2.4倍,最小完整震级由最初的ML1.9降至ML1.1。随后,依据最新目录计算了震后震源区的b值,并结合余震展布形态,初步分析此次地震发震构造。研究结果显示,余震序列在平面上显示出NNW-SSE优势展布方向,长度约14km,震源优势深度集中在3~15km;深度剖面展示出主震的发震断层面较陡,并且具有向西倾的趋势。综合主震震源机制解、余震展布形态和周边地质构造背景,认为巧家MS5.0地震发震断层可能为NNW-SSE向走滑性质的断裂,与2014年鲁甸MS6.5地震的发震构造密切相关。
关键词:  匹配定位方法  微震检测  巧家MS5.0地震  发震构造
DOI:
分类号:P315
基金项目:国家自然科学基金(42074103)资助
Microseismic Detection and Seismogenic Structure Analysis of the Qiaojia MS5.0 Earthquake in Yunnan Province in 2020
Xu Zhiguo1,2, Liang Shanshan3, Liu Jingguang3, Zhai Luyuan3, Shi Jianyu1, Zhou Yuanze2
1.National Marine Environmental Forecasting Center, Beijing 100081, China;2.College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China;3.China Earthquake Networks Center, Beijing 100045, China
Abstract:
In this paper,we used the Match and Locate(M&L)method to detect the mico-earthquakes through scanning the 24 hours continuous waveform of the Qiaojia MS5.0 earthquake in Yunnan on May 18,2020 recorded by seismic stations close to focal source,in which 327 missing micro-earthquakes were detected,and the complete magnitude was reduced from ML1.9 to ML1.4. Then,we calculated the b-value with the adding catalog of the Qiaojia earthquake sequence,and discussed the seismogenic structure of main shock preliminarily based on the spatial distribution of aftershocks. Our results show that the aftershocks are mainly distributed in the NNW-SSE direction extending about 14km,and the focal depth ranges from 3 to 15km. The depth cross-section shows that the seismogenic fault dips westward deeply. By integrating with the focal mechanism solution of the main shock,the distribution characteristics of aftershocks and the surrounding geological structure setting,we proposed that the seismogenic fault may be a strike-slip fault with NNW-SSE trending,and is closely correlated to the seismogenic structure of the Ludian MS 6.5 earthquake in 2014.
Key words:  Match and location method  Microseismic detection  Qiaojia MS5.0 earthquake  Seismogenic structure