地磁低点位移法的改进  

Improvement of geomagnetic low-point displacement method

作　　者：马亮 孙三健[2] MA Liang;SUN San-jian(Gansu Earthquake Agency,Lanzhou 730000,China;Hainan Earthquake Agency,Haikou 570203,China)

机构地区：[1]甘肃省地震局,兰州730000 [2]海南省地震局,海口570203

出　　处：《地球物理学进展》2020年第3期859-865,共7页Progress in Geophysics

基　　金：国家自然科学基金项目(41674046);甘肃省地震局地震科技发展基金(2015Q07)联合资助.

摘　　要：中低纬度地磁场平静太阳日变化Z分量的极小值出现的时刻常被用于地震预报,即"低点位移"法,但现有算法的时间格式和人工绘制突变界线的模式会产生较大的误差,本文在第一部分针对这些误差改进了原有算法.第一项是改进了地磁低点时间的格式,第二项是引入了Voronoi剖分技术替代人工画线.前者过滤了假的突变界线,消除了系统误差;后者建立了突变界线与地磁台网低点数据之间的解析关系,使它们一一对应,消除了随机误差.本文第二部分内容是提出了新的时间格式与数字化突变界线的计算公式,并用程序实现计算任务.本文第三部分内容是在对地磁台网的低点时间跟踪的过程中,捕捉到了甘肃省周边几次地震前的地磁低点位移现象,并分析这些案例,在结论中证明该方法的可靠性.The time when the minimum value of the Z component of the calm solar diurnal variation of the geomagnetic field occurs in the middle and low latitudes is often used for earthquake prediction,i.e.the“low-point displacement”method.However,the time format of the existing algorithms and the mode of artificially drawing the abrupt boundary will produce large errors.In the first part of this paper,the original algorithm is improved for these errors.The first is to improve the format of geomagnetic low point time,and the second is to introduce Voronoi subdivision technology to replace manual line drawing.The former filters the false catastrophe boundaries and eliminates the systematic errors,while the latter establishes the analytical relationship between the abrupt boundaries and the low-point data of the geomagnetic network,making them correspond one by one and eliminating the random errors.In the second part of this paper,an equation for a new time format and formulas for calculating the digital abrupt boundary are proposed,and the calculation task is realized by program.In the third part of this paper,the phenomenon of geomagnetic low-point displacement before several earthquakes around Gansu Province is captured in the process of tracking the low-point time of the geomagnetic network,then these cases are analyzed,which proves the reliability of the method in the conclusion.

关 键 词：地磁低点时间 突变界线 Dirichlet镶嵌 DELAUNAY三角网 

分 类 号：P318[天文地球—固体地球物理学]