伽师强震群活动期间地震窗异常特征研究

分析研究了1997－1998年伽师强震群活动期间阿困什余震窗和喀什地震窗月频、旬频、日频的异常特征。结果表明，两地震窗的异常形态具有一定的相似性，起止时间也具有同步性。月频度异常形态多经过2－3个峰值后在高值发震；旬频率、日频率异常形态则表现为高值－低值－发震；日频度异常出现在震前1－3d。通过对比分析伽师强震群1997年和1998年的活动特征发现，阿图什余震窗和喀什余震窗在1997年几组后续6级地震前小震日频率均在指数衰减背景上明显升高，而1998年2组强震前指数衰减背景不明显。

ON CHARACTERISTICS OF SEISMIC WINDOW ANOMALY DURING THE JIASHI EARTHQUAKES SWARM

A large number of seismologic windows in a great area, especially in the Tian shan earthquake belt, showed clear anomaly during the Jiashi strong earthquake swarm from 1997 to 1998.Strong earthquakes of the swarm can be divided into five groups according to the occurrence time.The first strong earthquake of each group can be checked out by the monthly and ten days microseism frequencies of Kashi and Atushi seismic windows. The succedent strong earthquakes of each group can be checked out by the daily microseism frequency of the Kashi and Atushi seismic windows.It can be found from the anomalous features that strong earthquakes occurred usually after a high value of monthly frequency or after a low value of ten days frequency and after a low value of daily frequency.It can be also found from the temporal process of the window anomalies that the duration and interval of the anomalies of Kashi and Atushi seismic windows during Jiashi earthquake swarm are longer than those of a single event.The duration of the anomaly during the first strong shock of each group is longer than that of the succedent strong earthquake.The daily frequencies of the two windows notably increased before the succedent strong earthquakes occurred from the exponential attenuating background in 1997, but in 1998 the daily frequencies increased before the strong earthquake occurred in the normal background.The results of the analyses indicate that the earthquake window is a valuable method in earthquake prediction.