一、引言近年来,国内外对强震发生前后,在较大范围伴随着一系列震群活动引起普遍重视,並有“前兆震群”的提法。人们试图从震群的空间分布、时间进程、测震学指标及震源特征等方面探讨所谓前兆震群与一般震群的区别,从中寻找前兆震群的判据和指标,以期为预报未 I. INTRODUCTION In recent years, before and after the occurrence of strong earthquakes both at home and abroad, widespread attention has been paid to a series of earthquake swarm activities in a large area with the formulation of “precursor swarm of shocks.” People try to explore the difference between the so-called precursor swarm and the general swarm from the spatial distribution of swarm, time course, seismological indicators and source characteristics, and find the criteria and indexes of precursor swarm in order to predict