四川长宁及周缘重力数据融合及深浅构造特征研究  

Gravity Data Fusion and Deep-shallow Structure Characteristics in Changning of Sichuan Province and Its Periphery

作　　者：麻继文 吴桂桔[1,2] 邹正波 谈洪波[1] 王嘉沛 MA Jiwen;WU Guiju;ZOU Zhengbo;TAN Hongbo;WANG Jiapei(Key Laboratory of Earthquake Geodesy,Institute of Seismology,China Earthquake Administration,Wuhan,Hubei 430071;Institute of Disaster Prevention,Langfang,Hebei 065201)

机构地区：[1]中国地震局地震研究所(地震大地测量重点实验室),湖北武汉430071 [2]防灾科技学院,河北廊坊065201

出　　处：《地球学报》2024年第6期977-988,共12页Acta Geoscientica Sinica

基　　金：中国地震局地震星火计划攻关项目(编号:XH21021);国家自然科学基金面上基金项目(编号:42074172);国家自然科学基金青年基金项目(编号:42204089)。

摘　　要：高精度地球物理数据是获取地壳内部物质变化的基础,2019年6月17日四川长宁发生MS6.0级地震,近期该区域多次发生5级左右地震,且区域内地震的发震诱因存在争议。本研究以实测重力剖面数据为基准,首先寻找重力场模型数据与实测重力剖面数据之间的映射关系式;然后对重力场模型数据进行修正,采用双线性插值法获取研究区内高精度网格数据;以长宁MS6.0地震震中为中心点,提取4条重力剖面并采用密度反演获取跨长宁MS6.0地震震中的地壳密度差变化特征。研究结果表明:通过重力场模型数据与实测重力数据间的映射关系式计算所获取的融合数据精度小于5%;长宁及周边震群发震区域对应三叠纪地层且震群多沿背斜、向斜发生;长宁MS6.0地震位于剩余布格重力异常0~30 mGal的正低值区域和密度反演高低转换带上0.048~0.058 g/cm^(3)的正低值区域,该区域位于长宁背斜上的大地湾断层与双河背斜轴部隐伏断层的交汇处。本研究可为多源重力数据融合提供技术基础,服务于以动力学为基础的地震物理预测。High-precision geophysical data is the basis for obtaining material changes inside the crust.On June 17,2019,a MS6.0 earthquake occurred in Changning,Sichuan Province.Recently,there have been several earthquakes of approximately magnitude 5 in this region,and the causes of earthquake occurrence in this region are controversial.First,based on the gravity profile data,the mapped relationship between the gravity field model data and the measured gravity profile data was determined.Next,the gravity field model data were modified,and high-precision grid data of the study area were obtained by bilinear interpolation.Using the epicenter of the Changning MS6.0 earthquake as the central point,four gravity profiles were extracted,and the characteristics of crustal density variation across the Changning earthquake epicenter were obtained using the density inversion method.The results showed that the accuracy of the fusion data obtained by the calculation of the mapping relationship between the gravity field model data and the measured gravity data was less than 5%.The earthquake clusters in Changning and its surrounding areas corresponded to the Triassic strata,and most occurred along the anticline and syncline.The Changning earthquake was located in the positive,low-value area of 0–30 mGal residual Bouguer gravity anomaly and 0.048–0.058 g/cm^(3) density,a high-low transition region.This area is at the intersection of the Dadiwan fault on the Changning anticline and a hidden fault on the Shuanghe anticline axis.This study provided the technical basis for multi-source gravity data fusion and could serve as a dynamic-based seismic physical prediction tool.

关 键 词：重力数据融合 布格重力异常 长宁地震 密度反演 

分 类 号：P315[天文地球—地震学] P631.1[天文地球—固体地球物理学]