用地震活动度变化特征进行地震序列类型早期划分

DIFFERENTIATE THE TYPES OF SEISMIC SEQUENCES AT EARLY STAGE WITH THE SEISMICITY'S VARYING CHARACTER

本文对我国1966～1991年全国6级以上地震序列进行研究,发现其早期(3-7天内)活动遵从下式:Lns=a-KsT.其中S为地震活动度,是时间T的函数,T以天为单位.以最小二乘法求取上式Ks值,并以其对序列类型进行划分,Ks≥0.145为主震型,Ks<0.145为震群型.将划分结果与传统分类结果比较,符合率约为86%.表明该值可作为一种较好早期分类指标,用于序列早期分类和震后趋势预测.

The paper has studied the seismic sequences of magnitude 6 and above in China from 1966 to 1991 and we have found the seismicity at the early stage (3 -7days) follows the following formula:LnS = a-KsTWhere S stands for the seismicity, being the function of T; T stands for the time measured by day; a and Ks are constants. Resolve the constant Ks with least square method and differentiate the types of the seismic sequences with it. A sequence with Ks> = 0. 145 belongs to the type of main earthquake, and a sequence with ks<0. 145 belongs to the type of swarm. Comparing the results with the traditional differentiating results, we have found that about 86 per cent of sequences belong to the same one of the two types in the two ways. This indicates that the Ks may be a better index to differentiate the type of a sequence at the early stage and wecan use it to predict the seismic tendency after a strong shock.