汶川8.0级地震前发震断裂带地震活动特征研究

Seismicity and stress field feature of the seismic fault zone before Wenchuan M 8.0 earthquake

设定两个不同研究区域,分别就汶川8.0级地震前地震活动特征进行研究,得出以下结论:①至少在2008年5月11日之前的38年时间中,龙门山断裂带中段出现M 5.0以上地震空段,汶川巨大地震就发生在这一空段;②第一研究区域强震释放能量出现阶段性梯次减少现象;③至2008年初,估算出第一研究区域地应力积累量已达5.0136×10^(16)J,相当于一次M 7.9强震所能释放的能量;④第二研究区域中小地震在龙门山断裂带中段的南端形成了几乎垂直相交的两条地震带,小震活动明显增多。

Setting up two different research areas,respectively,seismicity of two area before Wenchuan M 8.0 earthquake are analyzed.The conclusions obtained are：①At least in the 38 years before on May 11,2008,a more than M 5.0 seismic empty section appeared in the midsection of the Longmenshan fault zone,the Wenchuan great earthquake occursed in this empty section；②The energy that the strong earthquake released appeared echelon periodic decreasing phenomenon in the first study area； ③To the beginning of 2008,ground stress accumulation value has amounted to 5.0136 × 1016J,about a M 7.9 earthquake can release energy；④In the southernmost of the midsection of the Longmenshan zone,mid-small earthquakes formed two seismic zones,which cross nearly perpendicularly,in the second study area,small earthquakes clear increase.