2020—2021年南北地震带北段岩石圈磁场异常变化在地震预测预报中的应用  

Application of abnormal changes in the lithospheric magnetic field in the northern section of the North-South Seismic Belt from 2020 to 2021 in earthquake prediction and forecasting

作　　者：张瑜 陈双贵 闫万生 马辉源 岳敏 杨磊 雷光 杨龙 ZHANG Yu;CHENG ShuangGui;YAN WangSheng;MA HuiYuan;YUE Min;YANG Lei;LEI Guang;YANG Long(Earthquake Administration of Gansu Province,Lanzhou 730000,China;Lanzhou Geophysical National Field Science Observation and Research Station,Lanzhou 730046,China)

机构地区：[1]甘肃省地震局,兰州730000 [2]甘肃兰州地球物理国家野外科学观测研究站,兰州730046

出　　处：《地球物理学进展》2024年第4期1369-1381,共13页Progress in Geophysics

基　　金：甘肃省地震局地震科技发展基金(KY2303023);流动地球物理场观测项目(ZX1803001);国家自然科学基金(U2039206)联合资助。

摘　　要：岩石圈局部的剧烈变化如火山爆发、地震等会引起区域岩石圈磁场的快速变化,地磁学者一般通过监测区域磁场的变化并选用合理的模型来研究震磁关系.本文基于2020—2021年南北地震带北段流动地磁观测资料,通过日变通化改正、长期变化改正以及剥离岩石圈磁场等步骤来分析研究区域岩石圈磁场时空分布特征及7次中强地震发震位置各地磁要素的异常变化,结果发现:研究区域岩石圈磁场水平矢量形成数个弱变化区域,本文讨论的7次中强震均发生在岩石圈磁场水平矢量弱变化区内部或边缘地带,在发震位置处水平矢量出现了转向、发散、对冲或量级突变的趋势;岩石圈磁场各要素年变化等值线与发震位置也有相关性,具体表现为ΔD、ΔY、ΔZ、ΔF、ΔI、ΔX等值线的“0”值线与中强地震表现出较明确的位置特征,即发震位置靠近“0”值线,单从发震位置与“0”值线的距离看,ΔD、ΔY、ΔZ要优于ΔF、ΔI、ΔX三个要素,这种明显的震磁特征变化对中强震发震地点预测有较强的指向性;另外除茫崖5.5级地震外,其余地震距离依据岩石圈磁场要素异常划定的异常区均较近,其中门源6.9级地震、马尔康5.8/6.0级地震、杂多5.9级地震发震位置与最近的岩石圈磁场异常变化区距离在30 km之内,映震效果良好.Severe changes in the local lithosphere,such as volcanic eruptions and earthquakes,can cause rapid changes in the regional lithospheric magnetic field.Geomagnetic scholars generally study the seismic magnetic relationship by monitoring changes in the regional magnetic field and selecting reasonable mathematical models.This article is based on the mobile geomagnetic observation data of the northern segment of the north-south seismic belt from 2020 to 2021.Through daily variation normalization correction,long-term variation correction,and stripping of the lithospheric magnetic field,the spatiotemporal distribution characteristics of the regional lithospheric magnetic field and the abnormal changes of magnetic elements at the locations of 7 moderately strong earthquakes are analyzed and studied.The results show that the horizontal vector of the lithospheric magnetic field in the study area forms several weak variation regions,The 7 moderately strong earthquakes discussed in this article all occurred within or at the edge of the weak variation zone of the horizontal vector of the lithospheric magnetic field,and there was a trend of turning,diverging,hedging,or magnitude mutation in the horizontal vector at the location of the earthquake;There is also a correlation between the annual variation contour lines of various elements of the lithospheric magnetic field and the location of earthquakes,as shown in the following:the"0"value line of theΔD、ΔY、ΔZ、ΔF、ΔI、ΔX contour line shows a clear positional feature with moderate strong earthquakes,that is,the earthquake location is close to the"0"value line,and only from the distance between the earthquake location and the"0"value line,ΔD、ΔY、ΔZ is betterΔF、ΔI、ΔX,than three elements.This obvious change in seismic and magnetic characteristics has strong directionality in predicting the location of moderate to strong earthquakes;In addition,except for the Mangya earthquake with a magnitude of 5.5,all other earthquakes are relatively close to the anomaly

关 键 词：岩石圈磁场年变 中强地震 弱变化 “0”值线 

分 类 号：P318[天文地球—固体地球物理学]