摘要
近年来,在四川南部地区相继发生了2019年6月17日的长宁M_(S)6.0地震、2021年9月16日的泸县M_(S)6.0地震.本文结合研究区陆地实测重力数据与WGM2012布格重力异常模型获得融合布格重力异常,以已有的速度结构模型为参考,利用贝叶斯原理构建密度参数的后验分布模型,通过MCMC方法提取后验样本,获得该区域的地壳三维密度结构.在反演结果的基础上,对比了1936年马边M_(W)6.7和M_(W)6.8双震、1974年大关M_(S)7.1地震与长宁、泸县两次地震的震源区深部物性结构特征,发现马边和大关两次地震震源区深部密度结构不均匀性较强,长宁地震震源区深部具备一定的不均匀性,但在泸县地震震源区深部没有发现明显的密度异常体.研究认为:相比于马边、大关这类构造地震,长宁地震具有类似的地震深部构造物性特征,而泸县地震此类特征不明显.
The purpose of the present research is to analyze the density structure in the focal region of moderate-strong earthquakes in southern Sichuan.We main interested in four earthquakes,the Mabian M_(W)6.7 and M_(W)6.8 earthquakes in 1936,the Daguan M_(S)7.1 earthquake in 1974,the Changning M_(S)6.0 earthquake in 2019 and the Luxian M_(S)6.0 earthquake in 2021.This research estimated the crustal three-dimensional density structure of southern Sichuan by using Bayesian theory with taking the results of seismic receiver function as a reference.The gravity data used in the inversion is formed by fusion of the measured land-based Bouguer anomaly and the WGM2012 Bouguer gravity anomaly model.A comparison of the four earthquakes focal region reveals that the deep density structure of the focal region of Mabian and Daguan earthquakes is highly inhomogeneous,and the deep density structure of the Changning earthquake focal region is also certain heterogeneity.However,no obvious inhomogeneous is founded in the deep density structure of Luxian earthquake focal region.
作者
李永波
陈石
李红蕾
张贝
LI YongBo;CHEN Shi;LI HongLei;ZHANG Bei(Institute of Geophysics,China Earthquake Administration,Beijing 100081,China;Beijing Baijiatuan Earth Science National Observation and Research Station,Beijing 100095,China)
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2022年第11期4326-4340,共15页
Chinese Journal of Geophysics
基金
中国地震局地球物理研究所基本科研业务费专项(DQJB19A0121,DQJB22X12)
国家自然科学基金(42004074,U1939205,U1839210)联合资助.
关键词
重力反演
长宁地震
泸县地震
MCMC方法
三维密度结构
Gravity inversion
Changning earthquake
Luxian earthquake
MCMC method
Three-dimensional density structure
