2012年苏门答腊Mw8.6地震成因及与周边大震关系

Geodynamic Mechanism of the 2012 Sumatra Mw8.6 Earthquake and Relationships with Other Great Shocks in Surrounding Areas

巽他海沟西侧地壳北向运动的差异性是2012年苏门答腊地震发生的动力学成因.库仑应力计算表明,2004年和2005年苏门答腊2次特大逆冲型地震对本次地震具有显著的触发作用.有记录以来至2011年,本次地震的发震断裂带没有发生过7级以上地震,震源区附近存在5级地震空区,2004年大震后该空区被打破.震前6年、4.5年和3个月发生了3组前震活动,其中最显著的是震前3个月发生的7.2级直接前震.

The geodynamic mechanism of the great April 11,2012, Mw8.6 earthquake off the west coast of the northern Suma- tra, Indonesia is the difference of the crust northward movements in the west of Sunda trench. Furthermore, the results of stat ic stress calculation show that the shock was triggered by the 2004 devastating Mwg. 1 shock and the 2005 event of Mw8.6. There was no earthquake with Mw≥7.0 occurred in the seismogenic fault of the 2012 Sumatra shock from 1900 to 2011. In ad dition, a seismic gap with Mw≥5.0 was formed around the focal region and the gap was disturbed after the 2004 Sumatra earthquake occurred. Six years, four and a half years and three months before the great 2012 event, there were three groups of foreshocks respectively, and the MwT.2 event, the direct pre-earthquake, occurred three months prior to the Mw8.6 shock, is the most significant one in the three groups of foreshocks.