1996年丽江M_(S)7.0地震前后滇西地震预报实验场重力场时空演化特征  

Spatio-temporal Characteristics of the Gravity Field in the West Yunnan Earthquake Test Site Area before and after the Lijiang M_(S)7.0 Earthquake in 1996

作　　者：王斌 黄江培 杨雄 祝意青[1] 隗寿春 李岩 徐佰翔 刘蜀 苏晓明 WANG Bin;HUANG Jiangpei;YANG Xiong;ZHU Yiqing;WEI Shouchun;LI Yan;XU Baixiang;LIU Shu;SU Xiaoming(Second Crust Monitoring and Application Center,China Earthquake Administration,Xi'an 710054,Shaanxi,China;Yunnan Earthquake Agency,Kunming 650224,Yunnan,China)

机构地区：[1]中国地震局第二监测中心,陕西西安710054 [2]云南省地震局,云南昆明650224

出　　处：《地震研究》2025年第4期623-630,共8页Journal of Seismological Research

基　　金：国家自然科学基金(42374104,41874092);陕西省自然基金(2024JC-YBMS-203);云南省地震局地震科技专项(20242X03).

摘　　要：利用1989—1996年滇西地震预报实验场绝对重力和相对重力观测资料,采用逐年差分和多年累积的方法,分析滇西地震预报实验场内部不同时间尺度的重力场演变特征及其与丽江地震在时空上的对应关系,结果表明:①1992年以前,研究区内部重力场变化平稳,1993年出现局部变化,1995年变化急剧加大,震后快速反向调整,变化量值基本与震前多年累积相当,重力场演化特征与丽江地震存在高度时空对应关系,表明该时段重力场变化为丽江地震的孕震特征。②研究区差分及累积重力场动态演化过程中,在川滇菱形块体与滇西块体边界产生重力变化梯度带,表明这2个块体构造活动剧烈。③沿红河断裂带出现(-60~90)×10-8 m/s 2的重力变化高梯度带,其走向与红河断裂构造高度一致,反映区域重力场变化受主要活动构造控制,是地下深部壳幔物质运移的表现。Based on the results from the absolute gravity measurement and the relative gravity measurement in the period 1989-1996,the gravity field characteristics in the West Yunnan Earthquake Test Site area in different time scales and the gravity's spatio-temporal correspondence with the 1996 Lijiang M S7.0 earthquake were analyzed by the method of year-by-year differential and years of accumulation.The results reveal that:①Before 1992,the gravity field in the study area changed steadily,and there were partial changes in 1993.In 1995,the alteration increased rapidly and readjusted conversely after the Lijiang earthquake.The variation amplitude was basically equivalent to the accumulated values prior to the earthquake.The variation of the gravity field was spatially and temporally corresponded with the Lijiang earthquake,which demonstrated the seismogenesis of the Lijiang earthquake.②A gravity gradient zone was generated along the boundary between the Sichuan-Yunnan rhombic block and the western Yunnan block during the dynamic evolution of the gravity field differential and cumulation,indicating intense tectonic activity along both blocks;③A high gravity gradient zone which was highly consistent with the strike of the Red River fault appeared,with the value of-60×10-8 m/s 2 to the value of 90×10-8 m/s 2.This reflects that the changes in the regional gravity field are controlled by the main active structures and this unveils the migration of the deep Crust-Mantle material.

关 键 词：滇西地震预报实验场 丽江M S7.0地震 重力场 时变特征 

分 类 号：P315.726[天文地球—地震学]