新疆北天山Ms≥5.0地震前的中长期地震活动空间图像特征

SPATIAL PATTERN FEATURE OF MEDIUM-, LONG-TERM SEISMICITY BEFORE M_S≥5.0 EARTHQUAKES IN NORTH TIANSHAN, XINJIANG

对新疆北天山 1931年以来 6级以上、1970年以来 5级以上地震前的地震活动空间图像进行了分析 ,发现震前多有不同程度的地震空区或条带出现 ,其孕育时间一般为 8- 14年 ;震源深度呈现由浅而深、通常超过 2 5 km的变化 ,孕育时间一般为 3- 4年。同时对上述地震活动空间图像前兆特征的机理进行了定性分析 。

By analyzing the spatial pattern of seismic activities before the M-S≥5.0 earthquakes since 1970 and the M-S≥6.0 earthquakes since 1931, it is found that varying degrees of seismic gaps and strips appeared before the quakes. The pregnant time were usually 8-14 years; the source depth showed the variation from shallow to deep and generally over 25 km, and as a rule, the variation appeared 3-4 years before the shocks. In addition, a qualitative analysis on the developing mechanism of spatial precursor patterns of seismicity was made, and some questions such as the precision of the selected data, etc., were discussed.