2013年芦山MS7.0地震前重力场源变化分析

doi:10.12196/j.issn.1000-3274.2021.01.007

地震 ›› 2021, Vol. 41 ›› Issue (1): 78-92.doi: 10.12196/j.issn.1000-3274.2021.01.007

2013年芦山M_S7.0地震前重力场源变化分析

王林海¹, 陈石^1,2, 张贝¹, 卢红艳¹

1.中国地震局地球物理研究所, 北京 100081;
2.北京白家疃国家地球科学野外观测研究站, 北京 100095

收稿日期:2020-07-23 修回日期:2020-08-17 出版日期:2021-01-31 发布日期:2021-01-28
通讯作者: 陈石,研究员。E-mail:chenshi@cea-igp.ac.cn
作者简介:王林海(1992-),男,山东青岛人,博士研究生,主要从事时变重力数据处理方法研究。
基金资助:
科技部重点研发专项项目(2018YFC0603502); 国家自然科学基金面上项目(41774090); 地震联合基金项目(U1939205); 中国地震科学实验场专项(2019CSES0105)

Analysis of the Variation of Gravity Field Source Before the 2013 Lushan M_S7.0 Earthquake

WANG Lin-hai¹, CHEN Shi^1,2, ZHANG Bei¹, LU Hong-yan¹

1. Institute of Geophysics, China Earthquake Administration, Beijing 100081, China;
2. Beijing Baijiatuan Earth Science National Observation and Research Station, Beijing 100095, China

Received:2020-07-23 Revised:2020-08-17 Online:2021-01-31 Published:2021-01-28

摘要/Abstract

摘要： 陆地重力观测获取的时变重力信号是研究地壳内部孕震区介质变化的重要依据。利用贝叶斯平差方法处理了川西地区2010—2012年的流动重力观测资料, 发现相对重力仪的格值系数在两年内变化可达2×10^-4, 而且仪器存在较小的非线性漂移率; 重力场累积动态变化图像显示, 2013年芦山M_S7.0地震发生在重力梯度带零值线与龙门山断裂带交会部位附近。进一步采用等效源方法划定了测网内以雅安、康定和石棉为中心的场源分辨能力较高的区域, 并反演了地震前的地壳视密度变化。场源视密度动态变化结果表明: 2013年芦山M_S7.0地震前2年, 在龙门山断裂带的南侧和鲜水河断裂南段的东侧区域形成了范围较大的等效视密度增加区, 而在小金至康定一带和都江堰周边地区也存在小规模的视密度增加。本文基于陆地时变重力测量结果反演得到芦山地震前的地壳内部等效视密度变化, 可为研究壳内深部孕震环境变化特征提供参考。

关键词: 陆地重力观测, 贝叶斯平差, 重力变化, 等效源, 场源视密度反演

Abstract: The time-varying gravity signal obtained by land gravity observation is an important basis for studying the medium change in the seismogenic region of the crust. This paper employs Bayesian adjustment method to process the mobile gravity observation data of West Sichuan from 2010 to 2012. It is found that the scale factor of the relative gravimeter can change up to 2×10^-4 in two years, and the instrument has a small nonlinear drift rate. The cumulative dynamic change image of gravity field shows that the 2013 Lushan M_S7.0 earthquake occurred near the intersection of zero value line of gravity gradient zone and Longmenshan fault zone. Furthermore, the equivalent source method is used to delineate the areas with high field source resolution centered on Ya'an, Kangding and Shimian, and to inverse the crustal apparent density changes before the earthquake. The results of dynamic variation of field source apparent density show that: during the two years before the 2013 Lushan M_S7.0 earthquake, a large area of increasing equivalent apparent density was formed in the south side of Longmenshan fault zone and the east of the southern section of Xianshuihe fault zone, and small-scale of increasing apparent density was also found in the area from Xiaojin to Kangding and around Dujiangyan. In this paper, the equivalent apparent density change in the crust before the 2013 Lushan M_S7.0 earthquake is obtained by inversion based on the land time-varying gravity measurements, which can provide a reference for the study of the characteristics of the seismogenic environment in the deep crust.

Key words: Terrestrial gravimetry, Bayesian adjustment, Gravity variation, Equivalent source, Field source apparent density inversion

中图分类号:

P315.7

王林海, 陈石, 张贝, 卢红艳. 2013年芦山M_S7.0地震前重力场源变化分析[J]. 地震, 2021, 41(1): 78-92.

WANG Lin-hai, CHEN Shi, ZHANG Bei, LU Hong-yan. Analysis of the Variation of Gravity Field Source Before the 2013 Lushan M_S7.0 Earthquake[J]. EARTHQUAKE, 2021, 41(1): 78-92.

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2013年芦山M_S7.0地震前重力场源变化分析

Analysis of the Variation of Gravity Field Source Before the 2013 Lushan M_S7.0 Earthquake

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2013年芦山MS7.0地震前重力场源变化分析

Analysis of the Variation of Gravity Field Source Before the 2013 Lushan MS7.0 Earthquake

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2013年芦山M_S7.0地震前重力场源变化分析

Analysis of the Variation of Gravity Field Source Before the 2013 Lushan M_S7.0 Earthquake