南北地震带强震前时变重力水平梯度时空趋势分析  

Analysis of the Temporal and Spatial Trends of the Time-varying Gravity Field Prior to Strong Earthquakes on the North-South Seismic Belt

作　　者：于飞 吴桂桔[1] 郝洪涛[1] YU Fei;WU Guiju;HAO Hongtao(Key Laboratory of Earthquake Geodesy,Institute of Seismology,China Earthquake Administration,Wuhan 430071,Hubei,China)

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

出　　处：《地震研究》2025年第4期612-622,共11页Journal of Seismological Research

基　　金：国家自然基金面上项目(42074172).

摘　　要：南北地震带是中国强震频发区之一,分析该区域重力场时空变化趋势对理解强震机理、构造变形具有重要意义。引入二维水平梯度分析方法,基于2016年9月—2021年9月所获取的5期时变重力数据,计算南北地震带时变水平梯度值,结合研究区地震信息和地质构造资料,分析2017年以来研究区M S≥5.0震中区域地震震前时变水平梯度与地震活动的时空分布特征。结果表明:研究区M S≥5.3地震震中区域震前时变水平梯度特征与震级呈正相关;M S≥6.0地震震中区域震前时变水平梯度高值带逐渐沿块体边界、大型断裂展布,极大值大于1.7μGal/km,区域标准差大于0.4μGal/km。The North-South Seismic Belt is one of the regions where strong earthquakes occur frequently in China.Analyzing the temporal and spatial variation trend of the gravitational field on this belt is of great significance for understanding the mechanism of strong earthquakes and the tectonic deformation.In this paper,a two-dimensional horizontal gradient analysis method is introduced.Based on five periods of time-varying gravity data obtained from September 2016 to September 2021,the time-varying horizontal gradient values of the North-South Seismic Belt are calculated.Based on the records of the historical earthquakes(M S≥5.0)and the geological structure in the study area,the temporal and spatial distribution characteristics of the pre-earthquake time-varying horizontal gradient and the historical earthquakes(M S≥5.0)in the study area since 2017 are analyzed.The results indicate that the time-varying horizontal gradient before the M S≥5.3 earthquakes is positively correlated with the magnitude of these earthquakes.Before the M S≥6.0 earthquakes,the high-value zone of the time-varying horizontal gradient gradually extends along the block boundaries and the large faults.In addition,the maximum value can be greater than 1.7μGal/km,and the regional standard deviation can be greater than 0.4μGal/km.

关 键 词：南北地震带 时变重力场 二维水平梯度 中强震 

分 类 号：P315.726[天文地球—地震学]