华北北部地区地下水10年准周期及其与地震活动关系分析

10 years quasi cycle of groundwater level in northern part of North China and its relationship with seismic activity

1966年以来华北北部发生5.0级以上地震16次,根据时间上的密集程度可分为5个地震丛。地下水资料经过排出地下水超采造成的趋势下降干扰后,多井地下水资料呈现出10年准周期变化的同步性特征。地震丛发生在地下水多年周期的高值段,低值年份则没有中强以上地震发生。将10年准周期按一定规则分成低值段、上升段、高值段和下降段,在地下水10年周期4个时段的发震概率分别为0%、25%、50%、25%。

16 over M5.0 earthquakes occurred in the northern part of North China since 1966, and they are can be divided into 5 earthquake clusters. Eliminated the tendency interference that caused by overdraft, groundwater levels of many wells show a 10 years quasi cycle variation synchronously. The earthquake clusters occurred in the high value period yearly cycle, and no medium and strong earthquakes occurred in low value period. The cycle can be divided into four segments, which is lower, rising, higher and dropping segment. The probability that earthquakes occur in each segment is 0, 0.25, 0.5 and 0.25 respectively.