Stress and Seismicity Changes on the Sunda Megathrust Preceding the 2007 Mw 8.4 Earthquake
Stress and Seismicity Changes on the Sunda Megathrust Preceding the 2007 Mw 8.4 Earthquake
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2007 年 Mw 8.4 地震前巽他巨型逆冲断层的应力和地震活动变化
DOI：
10.1785/0120100063
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发表时间：
2011
影响因子：
3
通讯作者：
R. Bürgmann
中科院分区：
文献类型：
--
作者：
K. Wiseman;R. Bürgmann
2007年9月12日的明古鲁8.4级地震在时间和空间上与2004年苏门答腊-安达曼9.2级地震和2005年尼亚斯8.7级大逆冲地震接近，表明这可能是一次触发地震。它位于具有历史意义的1833 M 8.9破裂的南部。然而，令人困惑的是，巽他俯冲带在Nias和Bengkulu破裂带之间的部分，上一次在1797年m8.7事件中破裂，并没有首先出现。2004年和2005年大逆冲地震的库仑破坏应力（CFF）模型以及随后的震后松弛过程无法解释为什么2007年板块在1797年北部板块之前破裂。令人惊讶的是，规模小得多的2000 M w 8.0英加诺地震在2007年震源产生了更大的正CFF变化，这可能有助于解释2007年地震的南部位置。对2004-2005年地震后该地区地震活动率变化的调查表明，大逆冲地震可能在2007年断裂带北端附近动态触发了滑动。2000年地震后地震活动水平的大幅增加也可能影响了2007年地震的最终起始点。令人遗憾的是，在西比路附近的巽他巨型逆冲构造的最后一次破裂是在1797年，作为21世纪大型逆冲构造地震序列中唯一没有破裂的部分，它仍然对该地区构成巨大的地震危险。
Abstract The Bengkulu M w 8.4 earthquake on 12 September 2007, close in time and space to the 2004 M w 9.2 Sumatra–Andaman and 2005 M w 8.7 Nias megathrust events, suggests that it could be a triggered earthquake. It was located in the southern portion of the historic 1833 M w 8.9 rupture. However, it appears perplexing that the portion of the Sunda subduction zone between the Nias and Bengkulu rupture patches, which last ruptured in a 1797 M w 8.7 event, did not recur first. Coulomb failure stress (CFF) modeling of the 2004 and 2005 megathrust earthquakes and subsequent postseismic relaxation processes fails to explain why the 2007 patch ruptured before the northern 1797 segment. Surprisingly, the much smaller 2000 M w 8.0 Enggano earthquake produced a much larger positive CFF change at the 2007 hypocenter and may help to explain the southern location of the 2007 earthquake. Investigation of changes in seismicity rates in the region following the 2004–2005 events shows that the megathrust earthquakes may have dynamically triggered slip near the northern end of the 2007 rupture zone. A large increase in seismicity levels following the 2000 earthquake may also have influenced the eventual initiation point of the 2007 earthquake. Regrettably, the section of the Sunda megathrust near Siberut that last ruptured in 1797 still poses a great seismic hazard to the region as the only segment not to have ruptured in the sequence of twenty-first century megathrust earthquakes.