四川地区7级以上地震危险性分析

Seismic Risk Analysis of Earthquakes of M≥7.0 in Sichuan Province,China

对四川地区自 1 80 0年以来 7级以上地震发生时间间隔以及 1 90 0年以来四川地区7级以上地震与中国大陆地区巨大地震之间的相关关系进行了统计分析 ,得到如下结果 :自1 80 0年以来四川地区 7级以上地震发生的时间间隔平均约为 1 6年 ,最长为 3 4年 ,最短为 3年 ,时间间隔在 2 3年以下的占 83 %。自 1 90 0年以来 ,四川地区 7级以上地震平均时间间隔为 1 1年 ,最长为 1 9年 ,最短为 3年。自 1 90 0年以来四川地区发生的 7次 7级以上地震之前1～ 3年中国大陆地区都发生过 7.7级以上的巨大地震。从 1 976年以来四川地区已经 2 6年没有发生 7级以上地震 ,远远超出平均时间间隔。在这种背景下 ,2 0 0 1年 1 1月 1 4日在青海 -新疆交界发生了 8.1级巨大地震 ,很可能指示在未来 1～ 2年内 ,四川地区将发生 7级以上地震。从 2 0 0 3年起就应该警惕四川地区发生 7级以上地震的可能 !

The correlation between the time intervals of earthquakes of M ≥7 0 occurring since 1800 and earthquakes of M ≥7 0 occurring since 1900 in Sichuan Province and great earthquakes of M ≥7 7 in the mainland of China is analyzed statistically in the paper.With the result that since 1800 the mean time intervals of earthquakes of M ≥7 0 in Sichuan Province is about 16 years,the longest one is 34 years and the shortest one is 3 years.The time intervals below 23 years are 83%;since 1900 the mean time intervals of earthquakes of M ≥7 0 in Sichuan Province is 11 years,the longest one is 19 years and the shortest one is 3 years.Since 1900 one to three years before 7 earthquakes of M ≥7 0 occurring in Sichuan Province,great earthquakes of M ≥7 7 took place in the mainland of China.Since 1976 earthquakes of M ≥7 0 have not taken place in Sichuan Province and the time intervals have been far exceeded.Under this background, the great earghquake of M 8 1 occurring in the boundary between Xinjiang Uygur Autonomors Region and Qinghai Province on November 14,2001 maybe predicts that an earthquake of M ≥7 0 will take place in Sichuan Province in one or two years of the future.Beginning with 2003 we should pay more attention to the possibility of an earthquake of M ≥7 0 occurring in Sichuan Province.