摘要
利用傅立叶分析法分离出河西──祁连山地区重力变化的长波项和短波项，进而推导出重力场所产生的散度场计算公式，分别计算出各时段的重力散度值，绘制出重力变化的长波项和短波项及散度等值线图。并结合该地区的地震活动和地壳深部构造资料进行综合分析研究，初步得出以下认识：①重力非潮汐变化的长波项是由地壳深部物质迁移所引起，具有NW向特征，与区域构造运动的继承性有关，通常把它作为地壳运动的正常值；②重力非潮汐变化的短波项是由地壳浅部因素引起，其图像特征与区域构造活动密切相关，地震前出现的高梯度带与震中在空间上有一定联系，说明重力短波项高梯度带与地震前兆有关；③几次中强地震均发生在重力散度场的正源区内。重力散度正源区是介质密度减小的区域，其特征与地震前兆现象相吻合；④重力非潮汐变化的短波项图像的高梯度带和重力散度场图像的正源区虽然都与地震有一定的联系，但二者的物理意义不同，散度图像有比较明确的物理解释，并且避免了人为划分长、短波项的主观因素影响。
In this paper, the Fourier-analysis method is used to separate the longwave andshortwave information of gravitational deformation of Hexi-Qilian area. The studyreaches the following conclusionst 1. The longwaves show that the movement of materialunder the earth's crust is the background of earthquake activity; but the shortwaves are re-lated to earthquake precursors, 2. The trait of both the longwave and the shortwave havehigh grade area, but their physical meaning is different; The high grade area of thelongwave is caused by the different structures of earth's crust; The high grade area of theshortwave is the earthquake risk region; 3. The source of the vertical force of Hexi-Qiliarnarea is in some blocks and a short time that results from the movement of the material un-der the crust that is in some blocks and in a short time.
出处
《地震》
CSCD
北大核心
1997年第3期304-312,共9页
Earthquake
关键词
重力测量
重力场
垂直形变
地震前兆
Gravity survey, Gravity field, Vetrical deformation, Earthquake precursor
