青藏高原6.0~6.9级地震前ML≥4地震平静异常研究*

(青海省地震局,青海 西宁 810001)

6.0~6.9级地震; 地震平静; 青藏高原

Research on Quiescence Anomaly of ML≥4.0 Earthquakes before M6.0~6.9 Earthquakes in Qinghai-Tibetan Plateau
CHEN Yu-hua,YAO Jia-jun,MA Yu-hu

(Earthquake Administration of Qinghai Province,Xining 810001,Qinghai,China)

M6.0~6.9 earthquakes; seismic quiescence; Qinghai-Tibetan Plateau

备注

对1975年以来青藏高原36个(25组)6.0~6.9级强震前ML≥4地震活动图像演化特征跟踪分析,发现92%的地震前震源区及外围出现清晰的ML≥4地震平静区。平静面积多在1×106 km2内,平静时段多集中在200~700 d,92%的地震发生在平静区内部。从地震预测角度认为,ML≥4地震大面积平静为青藏高原6.0~6.9级地震前一个具有鲜明特征的共性异常,它可以为青藏高原6级地震发生地点的判定、场的追踪提供依据。

Tracing and analyzing the seismic activity evolution characteristic of ML≥4 earthquakes before 36(25 groups)M6.0~6.9 strong earthquakes in Qinghai-Tibetan Plateau since 1975,we found that there appeared the clear seismic quiescence area of ML≥4 earthquakes in epicenter and its periphery before 92% earthquakes. The area of seismic quiet was less than 1×106 km2,the quiet period focused on 200~700 d,and the 92% earthquakes occurred inside the seismic quiet area. On the aspect of earthquake prediction,we considered that the large area of seismic quiet of ML≥4 earthquakes was the common anomaly with distinct characteristic before M6.0~6.9 earthquakes in Qinghai-Tibetan Plateau,which could be used to judge the location of M6.0 earthquake in Qinghai-Tibetan Plateau,and provide the basis of field tracing.