南北地震带两次典型强震周边自然电场变化及机理探讨

Change and Mechanism of Spontaneous Potential Field around Two Typical Strong Earthquakes in the North-South Seismic Zone

根据场源不同可将地电场E分为大地电场ET和自然电场ESP。空间Sq电流系和固体潮一般被认为是大地电场ET的起源;自然电场ESP源于地下介质的物理化学作用,其局部性变化相对稳定。2013年南北地震带相继发生了芦山MS7.0地震(30.3°N,103.0°E)和岷县、漳县MS6.6地震(34.5°N,104.2°E)。两次地震周边约400 km范围内的地电场台站(成都、汉王)数据表明震前自然电场ESP出现明显的小幅度突跳或大幅度跃变,同时在时间上具有准同步性,其他地电场台站也有类似变化。基于大地电场岩体裂隙水(电荷)渗流(移动)模型,对两次地震周边自然电场ESP的变异机理进行探讨,尝试解析其物理过程。

The geoelectric field E can be divided into telluric field ET and spontaneous potential field ESP according to different field sources.The spatial Sq current system and the solid tide are generally considered to be the origin of the telluric field ET;the potential field ESP originates from the physical and chemical actions of the underground medium,and the local changes are relatively stable.In 2013,the Lushan MS7.0 earthquake(30.3°N,103.0°E)and the Minxian-Zhangxian MS6.6 earthquake(34.5°N,104.2°E)occurred successively in the north-south seismic zone.The data of geoelectric stations(Chengdu,Hanwang)within about 400 km around the two earthquakes indicated that the potential field ESP before the two earthquakes both showed significant small or large jumps,and the change was quasi-synchronized in time.Similar changes occurred in other geoelectric stations.Based on the seepage(movement)model of the fissure water(charge)of the telluric field rock mass,the variation mechanism of the spontaneous potential field ESP around the two earthquakes was discussed,and its physical process was analyzed.