大当量爆破地震波记录分析

ANALYSIS ON EXPLOSIVE SEISMIC WAVE WITH LARGE YIELD

通过对首都圈地震台网和河北地震局流动台网大当量爆破记录的分析,发现爆破激发的地震波传播特性与天然地震波有明显差异,其主要特征有:1)爆破能量衰减很快,总体以e-1.5衰减;但是近场(<20 km)与远场(>20 km)衰减有显著差异;2)部分远场台站有能量增强的现象,震波振幅的增减与井下观测还是地面观测无关,与场地效应等关系密切,反映了某些区域各种波的多次叠加效应;3)爆破的S波传播速度明显低于天然地震,P波差异较小,可能与爆破源不利于剪切波的激发有关。

Through the analysis on the records of digital seismic network in the Capital area and mobile network of the Earthquake Administration of Hebei Province, it is found that explosive seismic wave is obviously different in its propagating feature from that of the natural seismic wave. The main characteristics of the explosion are as follows： 1 ） the explosive energy decayes quickly, wholly with e^-1.5 ; but the decaying rate is apparently different in near field （ 〈 20 km） and far field （ 〉 20 km） ;2） there are phenomenon of increasing energy at part of far field stations; the increase and decrease of the amplitude of explosion wave is not related to the station location of well or ground, but to the site effect, which reflects the overlapping effect of many kinds of waves;3 ） the S wave velocity of explosion is obvious lower than that of natural earthquake, while P wave velocity is similar, it may be related to the cause that explosion is not favorable to stimulate shear wave.