鲁南地区地震活动性异常与苍山ML5.6级地震

利用《地震学分析预报方法程式指南》中的方法分析了鲁南地区的地震活动性异常，发现在苍山ＭＬ５．６级地震前，鲁南地区２３个月无ＭＬ≥２．５级地震；在１９８５年６月新泰ＭＬ４．１级地震以后，ＭＬ≥３．０级地震主要集中在新泰苍山莒县之间的三角地带；１９７４年以后沿苍尼断裂的ＭＬ≥３．０级地震都发生在５．６级地震震中附近。地震应变能释放自１９８年以后出现较明显的加速过程；ｂ值、地震活动度Ｓ值、最大震级缺震曲线均出现低值异常。

STUDY OF THE TEMPORAL REGULARITIES OF HISTORICAL EARTHQUAKES IN GUANZHONG BASIN,CHINA

The temporal regularities of earthquakes in Guanzhong basin are studied by analyzing historical earthquake records of Shanxi province. The quiet periods of about 570 years and the active periods of about 240 years occur alternatively in Guangzhong basin. The present belongs to the third quiet period. By studying historical earthquakes of the third quiet period from 1481 to 1720, the property of earthquakes clustering is found. The average time of the sub-activity periods is about 6 years. The sub-activity periods have a relatively high energy increased one by one before any intensive earthquake, or a relatively low energy released before the bigger earthquake. The temporal regularity of earthquakes is important to understand the earthquake situation at present.