【摘要】 结合1900~2013年的历史地震目录,对青藏块体及其邻区不同震级段地震的发生频率进行计算分析,得出如下结论:1900年以来,青藏块体及邻区仅5年未发生M≥5.5地震,有16年未发生M≥6.0地震,有36年未发生M≥6.5地震,即M≥5.5、M≥6.0及M≥6.5地震年发生概率分别为0.956、0.86及0.68。对该区域历史有记载的地震进行分震级段的b值计算,得出5.5≤M≤7.0震级段地震的b最低为0.59,最高为0.899,M≥7.1震级段的b值均大于1.0,M≥7.5震级段的b值明显低于相邻震级段,表明未来存在发生7.5级左右地震的可能。最后对2000年以来研究区M≥6.5地震的空间迁移规律进行分析,得出青藏块体内部地震存在顺时针迁移的特征的结论。更多还原

【Abstract】 Using the history earthquakes catalogue from 1900 to 2013,we analyze the frequency of earthquake occurrence in different magnitude section,and get the following conclusions: there were not occurred M ≥5.5 earthquakes in 5 years,M ≥6.0 earthquakes in 16 years,and M ≥6.5 earthquakes in 36 years in Qinghai-Tibet Block and its adjacent area since 1900.The annual occurrence probability of M ≥5.5,M ≥6.0 and M ≥6.5earthquakes were close to 0.956,0.86 and 0.68 respectively.Furthermore,we calculated b-value of each magnitude section of the earthquake recorded in history,and obtained that the b-value of 5.5≤M ≤7.0 earthquakes was from 0.59 to 0.899,the b-value of M ≥7.1 earthquakes is greater than 1.0,and the b-value of M ≥7.5earthquakes was significantly lower than the adjacent magnitude section.It shows that there may occur M7.5earthquake in the future.Finally,we analyzed the space migration patterns of M ≥6.5 earthquakes since 2000,and got that the characteristic of earthquake exist the regular of clockwise migration.更多还原