【摘要】 对许昌市1000年以来的地震记录进行统计分析后,发现许昌地区的地震具有震群型地震和孤立型大震相间分布的特点,地震活跃期一般持续4～20年左右。地震平静期为60年的倍数,即大震发生的周期为120年,地震发生的位置多分布在许昌市的东南、东北10km的范围之内,引发地震的活动断裂为开封—汝南深大断裂和许—禹断裂。更多还原

【Abstract】 After studying the records of the historical earthquakes in Xuchang,a fact is found that there is an interval between groups of small earthquakes during which big earthquakes take place. The active period usually lasts about 4 ~ 20 years and the peaceful interval is about 60 years and its multiple,that is,the big earthquakes take place in a circle of 120 years, 180 years or so.Locations of the earthquakes are mainly in Northeast of Xuchang in 10 km distance area. A main zone of fractures which makes those earthquakes occure are Kaifeng-Runan fracture and Xuchang-Yuxian fracture.更多还原