东南沿海地震带M≥5级中强地震活动的时空丛集特征

Spatial-temporal Clustering Characteristics of M≥5 Moderate and Strong Seismic Activities in the Southeast Coastal Seismic Belt

东南沿海地震带M≥5级中强地震活动有时空丛集的特征,有历史记录以来东南沿海地震带经历了3个7级强震的活动周期,其中以1600年广东南澳7.0级、1604年福建泉州海外7.5级、1605年海南琼山7.5级3次7级地震为主释放的第一强震活动周期与以1994年台湾海峡7.3级、和1994、1995年北部湾6.1、6.2级地震为主释放的第三强震活动周期具有较为相似的时空活动特征。在主释放期东南沿海地震带东西端都发生了6、7强震并且时间上有呼应的关系。在主释放后主要以5、6级中等地震活动为主,活动的主体地区在东南沿海地震带东段以及中段的粤桂交界地区,这对目前东南沿海地震带新一轮的5、6级地震活动空间主体地区的判断具有指示意义。而以1918年广东南澳东7.3级地震为主释放的第二活动周期活动则不同,此次主释放期的强震集中在东南沿海地震带的中到东段。西段未发生时间上有强呼应关系的中强地震,而随后的调整期地震仍然集中在东西两端,但相对分散在外围。

The moderate and strong earthquakes in the southeast coastal seismic belt are characterized by spatialtemporal clustering.Since historical records began,the southeast coastal seismic belt has experienced three active periods of strong earthquakes with M≥7.The temporal and spatial activity patterns of the first active period,which is mainly released by the Nan’ao M 7.0 earthquake in 1600,Quanzhou overseas M7.5 earthquake in 1604,and the Qiongshan M7.5 earthquake in 1605,are similar to the third strong earthquakes period mainly released by the Taiwan Strait M7.3 earthquake in 1994,Beibu Gulf M6.1and M6.2 earthquakes in 1994 and 1995.In these two periods,the strong earthquakes occurred in the east and west end of the southeast coastal seismic belt during the main release stage and has a corresponding relation in the time.In the post-release stage,the main earthquakes are mainly moderate earthquakes with M5-6,and the main activity area is the eastern section of the southeast coastal seismic belt and the middle section of Guangdong-Guangxi junction,which has indicative significance for the current judgment of the main area of seismic activity with M 5-6 in the southeast coastal seismic belt.The second period of activities which is released mainly by the Nan’ao M 7.3 earthquake in 1918 has different spatial-temporal clustering characteristic.The strong earthquakes in the main release stage are concentrated in the middle-east part of the southeast coastal seismic belt and no moderate-strong earthquakes occurred in the western segment in time,while the earthquakes in the subsequent adjustment stage are still concentrated at the east and west ends,but are relatively scattered in the periphery.