摘要:
本文再给出1976年7月唐山地震以外的我国10次地震前地电阻率(ρx)变化的震例,其中包括 M≥6的强震震例5次.每次地震前震中附近均有二个以上的台记录到(ρx)值同步变化.部分震例还对比给出地电阻率台附近测地基线的资料.发现不少地震前震中区浅层的(ρx)值有下降现象,这与唐山震例[1,2]相似,但也记录到(ρx)值上升或反复升降的例子.目的只是为了提供和积累更多的现象.因为一次大地震前,在震中附近设有地电阻率观测台而有记录的机会,就全世界来说尚是极少的.尽管这种变化仅局限于地表以下的浅层.
Abstract:
Other then the 1976 Tangshan Earthquake, ten more examples of changes in earth-resistivity (ρx) prior to strong earthquakes, five of which with magnitudes M6, are given in this paper. There are always at least two earth-resistivity recording stations located around the epicentral area of each of the earthquakes, recording the changes of ρx values, quite in accord with each other. For a part of the earthquakes are given also data of repeated base line surveys, in the vicinity of some of the earth-resistivity stations for comparison.For many cases, the earth-resistivity values of the shallow layers below the ground surface decrease prior to the earthquakes, just as in the case of the Tangshan earthquake. However, in, a number of cases, they increase or vary irregularly. The purpose of this paper is merely to provide an accumulation of more such observed phenomena of earth-resistivity changes around epicentral areas before and after strong earthquakes. It is because that earth-resistivity changes observed at stations before and in the vicinity of strong earthquakes are rare opportunity so far as such observations carried out in earthquake regions of the whole world are concerned, despite such observed changes in earth-resistivity is restricted to very shallow layers of the ground.
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