晋冀蒙交界中强地震前的中等地震平静-活跃-平静演化

Quiescence-seismic-quiescence evolution of medium-earthqakes before moderate-strong shocks in junction region of Shanxi,Hebei and Neimenggu

利用历史有感地震目录,研究晋冀蒙交界地区1484年以来18个(组)中强地震前的中等地震活动,概括为"长期平静—打破平静—主震"和"长期平静—打破平静—再度平静—主震"两种主要演化模式.认为:1)时间上,出现中等地震长期平静、打破平静以及再度平静现象是晋冀蒙交界地区中强地震前的重要前兆特征,打破长期平静后1年左右和再度平静后2～3年发生主震的可能性较大;2)空间上,打破平静的中等地震对未来主震的发生地点有指示意义,未来主震发生在其周围150km内或者中等地震集中分布区附近的可能性较大;3)强度上,出现具有上述两种模式典型特征的异常,尤其以4.5级以上地震打破平静时,发生5.5级以上地震的可能性较大.

We have studied 18 groups medium-seismic activities before moderate-strong earthquakes since 1484 with the historical sensible earthquakes in junction region of Shanxi,Hebei and Neimenggu and get two evolution models as＂longterm quiescence-quiescence broken-main shock＂and＂long-term quiescence-quiescence broken-once again quiescencemainshock＂.（1）in time,the phenomenon that from long-term quiescence of medium-earthquakes to quiescence broken even once again quiescence is an important precursory characteristic in junction region of Shanxi,Hebei and Menggu. The mainshock propably occurs about one year after long-term quiescence broken and two to three years after once again quiescence;（2）in space,the medium-earthquake breaking quiescence has Indicative significance to the hypocentral location of coming mainshock which always occurs about 150 kilometers around it or nearby the medium-earthquakes concentrated distribution area;（3）in strength,when the above two typical evolution models appear,in particular MS≥4.5earthquakes break the quiescence,the occurrence of MS≥5.5earthquakes have the large probability.