天山地震带多震层分布及大震前地震活动特征

天山地震集中发生于多震层(Seismogenic Layer)中,中强震及巨大地震则均发生在地壳上部的多震层中。多震层的分布与地壳厚度、低速层、地质构造及其它地球物理因素有关,且天山东、中、西各段多震层的分布特征各异。通过对研究区中强地震主体活动分区、划分地震幕及分析其它地震活动性参数认为:近百年来中亚地区地震活动的演化经历了几次起伏式的大衰减。目前天山地震带东段为地震活跃带。本文用勃朗(Brown)线性指数平滑预测方法预测该段未来7.0级大震可能发生的时间为1994年左右。

MULTIPLE SEISMOGENIC LAYERS ON TIANSHAN SEISMIC ZONE AND PRESHOCK ACTIVITIES

Most of the earthquakes in Tianshan region are generated in seismogenic layers,with huge and moderate ones in the upper part of the crust. It is found that their distributions are associated with crustal thickness, low velocity layer, tectonic setting and other geophysical factors, and resulting in variations in each layer differently. After division analysis and parameters studies,it is considered that since several uneven great attenuation in seismicities has been undergone over hundred years in Central Asia, and at present the east segment of Tianshan is in its active period. Using Brown's linear index smoothing predicted method,the occurrence time of huge earthquakes is predicted around 1994, with magnitude about 7. 0.