三亚M_(S)4.2地震前后海南岛重力场变化及其小波多尺度分解  

Gravity Field Changes in Hainan Island before and after Sanya M_(S)4.2 Earthquake and its Wavelet Multiscale Decomposition

作　　者：李盛[1] 黄章荣 胡久常[1] 解晓静[1] 贾伟 LI Sheng;HUANG Zhangrong;HU Jiuchang;XIE Xiaojing;JIA Wei(Hainan Earthquake Agency,13 Meiyuan Road,Haikou 570203,China)

机构地区：[1]海南省地震局,海口市570203

出　　处：《大地测量与地球动力学》2023年第9期945-949,979,共6页Journal of Geodesy and Geodynamics

基　　金：中国地震局地震科技星火计划(XH21024Y);中国地震局震情跟踪定向工作任务(2019010202,2020010213)。

摘　　要：利用海南岛流动重力测网2016~2022年共13期复测资料,分析研究区域差分重力场和累积重力场动态变化,并着重分析2019-08-20海南三亚M_(S)4.2地震前后海南岛西南地区重力场时空变化。结果表明,三亚M_(S)4.2地震震中附近地区在震前2 a和3 a出现重力场累积变化梯度带,梯度带的异常范围约60 km,重力场变化最大约为60μGal;三亚M_(S)4.2地震之后,震中附近地区重力场继续上升,至2020年下半年才开始协同下降,在下降过程中,发生以2021-08-08乐东MS3.2地震为最大地震的震群事件。对2016-09~2019-08海南岛累积重力场动态变化小波多尺度分解表明,海南岛西南地区重力场变化在3阶、4阶和5阶小波细节图中均出现异常。Using the repeated measurement data from Hainan island mobile gravity survey network of 13 periods from 2016 to 2022,we analyze the dynamic changes of differential gravity field and cumulative gravity field in the study area,and emphatically analyze the spatial and temporal changes of gravity field in the southwest of Hainan island before and after the Sanya M_(S)4.2 earthquake on August 20,2019.The results show that before 2 and 3 years of Sanya M_(S)4.2 earthquake,in the area near the epicenter of the Sanya M_(S)4.2 earthquake a gradient zone of cumulative change of gravity field appears,the anomaly range of gravity variation gradient zone before the earthquake is 60 km,and the maximum variation of gravity field is about 60μGal.After the Sanya M_(S)4.2 earthquake,the gravity field in the area near the epicenter continued to rise and began to decline in coordination until the second half of 2020.During the decline,a swarm event occurred with the Ledong 3.2 earthquake on August 8,2021 as the largest earthquake.The wavelet multi-scale decomposition of the dynamic changes of the cumulative gravity field in Hainan island from September 2016 to August 2019 shows that the gravity field changes in southwest Hainan island are abnormal in the third,fourth and fifth order wavelet detail maps.

关 键 词：三亚M_(S)4.2地震 重力场变化 梯度带 小波多尺度分解 

分 类 号：P315[天文地球—地震学] P312[天文地球—固体地球物理学]