后续地震发生时间估计及序列性质判定——以海城7.4级、巴楚—伽师6.8级地震序列为例

FOLLOW EARTHQUAKES OCCURRING TIME ESTIMATION AND SEQUENCE CHARACTER JUDGMENT-EXEMPLIFIED BY HAICHENG M_S7.4 AND JIASHI-BACHU M\-S6.8 EARTHQUAKES

在前人研究的基础上,给出利用参数k判定序列性质及利用前期地震预测后续地震发生时间的方法。理论分析表明,参数k以0为界,不同的取值表征了不同的地震活动状态,这与地震趋势估计及后续地震预测密切相关。k<0表明地震间时间间隔逐渐增长,呈现一种类似余震序列逐渐衰减的活动特征;k=0意味着地震间时间间隔不变,地震活动表现为以T为周期的准周期性活动;k>0表明地震间时间间隔逐渐缩短,呈现一种类似前震序列或地震累积频次指数增长的异常活动特征。如果k值在正、负区间随机分布,则该组地震之间无相关性可言。利用1975年2月4日海城7.4级地震前、余震序列及2003年2月24日巴楚—伽师6.8级地震序列对上述方法进行了检验并对有关问题进行了初步讨论。

A method was given to judge sequence character with parameter k and to forecast follow earthquakes using previous shocks on the basis of the predecessors' research. The theoretical analysis shows that parameter k has zero as the boundary and the different value indicts different state of seismic activity, which is closely related to earthquake trend estimation and prediction of follow shocks. Parameter k<0 means the interval between the events will gradually lengthen, and with the seismicity similar to gradually damping aftershock sequence; k=0, the interval between the events will keep invariable, the seismicity with the character of quasiperiod activity with T as period; k>0, the interval will gradually shorten, the seismicity similar to foreshock sequence or the abnormal activity that the earthquake accumulation frequency grows in exponent. If value k distributes in positive and negative intervals randomly, there is no correlation among this group of earthquakes. The foreshock and aftershock sequences of the Haicheng M\-S7.4 earthquake on Feb.4, 1975 and the sequence of the JiashiBachu M\-S6.8 earthquake of Feb.24, 2003 were used to test above method, and some problems were discussed primarily.