中国大陆6级以上强震及震前小震固体潮调制异常特征分析

Characteristics of earth tide modulation ratio of small earthquakes before strong earthquakes above M6 in Chinese Mainland

通过对2009年以来中国大陆13次6级以上浅源强震的固体潮调制作用进行回顾和分析,得到以下认识:(1)中国大陆6级以上强震在月相期内发震频率较高,即受固体潮调制作用明显;(2)朔望期潮汐应力的作用有利于走滑型和正断型地震的活动,其中对走滑型地震的触发效应较显著,固体潮汐对不同展布方式和运动性质的地震断层所产生的作用和效果存在差异;(3)6级以上强震前震源区附近小震调制比异常普遍存在,包括部分发生于非月相期内的6级以上强震前的小震也受到明显的固体潮调制作用;尤其需要关注震前小震调制比异常区逐渐向震中收缩且异常区面积逐渐减小的现象。

This paper reviewed and analyzed the modulation ratio of the earth tides during 13 strong earthquakes above M6 in Chinese Mainland since 2009.The conclusions are as follows:(1)The strong earthquakes with M≥6 in Chinese Mainland occur frequently during the lunar phase,that is,they are obviously modulated by the solid earth tide;(2)The effect of tidal stress during the lunation is beneficial to the activities of strike slip and normal earthquakes,and the triggering effect on strike slip earthquakes is more significant.The effects of solid tide on seismic faults with different distribution modes and movement properties are obviously different;(2)Before the strong earthquakes with M≥6,the modulation ratio anomalies of small earthquakes near the focal area are widespread,including some small earthquakes occurring in the non-lunar phase period.Special attention should be paid to the phenomenon that the abnormal area of small earthquake's modulation ratio gradually shrinks to the epicenter and the abnormal area gradually decreases before the earthquake.