华南内陆5级以上地震前小震活动增强分析

Analysis on Small Earthquake Activity Enhancement Before Earthquakes with M≥5 in Inland South China

对1970年以来华南内陆8次5级以上地震前小震活动增强开展分析,总结提取震前的小震活动增强的共性特征,并给出了震前小震增强跟踪策略。1970年以来华南内陆8次5级以上地震前均出现较显著小震活动增强现象,小震活动增强可作为华南内陆震情跟踪的一项重要预测指标;震前小震活动以增强—平静—发震为主,1970—2010年和2011—2021年5级以上地震前分别出现M_(L)≥3.0和M_(L)≥2.5地震集中增强,且至少发生一次M_(L)≥4.0地震;东南沿海地震带西段5级以上地震的优势发震时段是增强结束后6.5个月内,东南沿海地震带东段和右江地震带为19~33个月内;目标地震一般发生在地震集中增强/活跃区及周边地区;今后应加强华南内陆M_(L)≥2.5地震集中增强/活跃及其时空演化现象的跟踪研判。

This paper analyzes the enhancement of small earthquakes before 8 earthquakes with M≥5 in inland South China since 1970,summarizes and extracts the common characteristics of the enhancement of small earthquakes before earthquakes,and gives the enhancement tracking strategy of small earthquakes before earthquakes.There has been enhancement increase of small earthquakes before 8 earthquakes with M≥5 in inland South China since 1970,the enhancement of small earthquakes can be used as an important prediction index for earthquake tracking in inland South China.Before the earthquake,the activity of small earthquakes is mainly enhanced-calm-seismogenic.From 1970 to 2010 and from 2011 to 2021,there were concentrated enhancement of earthquakes with M_(L)≥3.0 and M_(L)≥2.5 before the earthquakes with M_(L)≥5.0,and at least one earthquake with M_(L)≥4.0 occured.The dominant period for earthquakes with M≥5 in the west section of the southeastern coastal seismic belt is within 6.5 months after the end of enhancement,while that in the east section of the southeastern coastal seismic belt and the Youjiang seismic belt is within 19-33 months.The target earthquakes generally occur in the earthquake concentrated enhancement or active area and the surrounding areas.In the future,it is necessary to strengthen the tracking research and judgment of the concentrated enhancement or activity and spatio-temporal evolution of earthquakes with M_(L)≥2.5 in inland South China.