Time-varying interseismic strain rates and similar seismic ruptures on the Nias–Simeulue patch of the Sunda megathrust
Time-varying interseismic strain rates and similar seismic ruptures on the Nias–Simeulue patch of the Sunda megathrust
复制标题
巽他巨型逆冲断层 Nias-Simeulue 斑块上随时间变化的震间应变率和类似的地震破裂
DOI：
10.1016/j.quascirev.2015.06.003
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发表时间：
2015
影响因子：
4
通讯作者：
R. Briggs
中科院分区：
文献类型：
--
作者：
A. Meltzner;K. Sieh;H. Chiang;Chung‐Che Wu;L. Tsang;Chuan‐Chou Shen;E. Hill;B. Suwargadi;D. Natawidjaja;B. Philibosian;R. Briggs
2005 年大逆冲断层 (MW8.6) 上方的边缘礁石中的微环礁化石，在历史报道的 1861 年大地震中记录了隆起。这些证据几乎涵盖了 2005 年大断层的整个 400 公里走向长度，此前已表明该断层受到两个持久的地震破裂屏障的限制。此外，在我们限制 1861 年隆升幅度的地点，它与 2005 年的隆升幅度相当。因此，1861 年和 2005 年的破裂在程度和幅度上似乎相似。在一个地点，公元 1422 年左右的隆起似乎也模仿了 2005 年的隆起量。巽他巨型逆冲断层的尼亚斯-锡穆卢部分的某些破裂之间的高度相似性与巽他巨型逆冲断层的苏门答腊部分的其他部分的破裂之间的巨大差异形成鲜明对比。在尼亚斯岛西北端的一个地点，珊瑚礁也在公元 1843 年的一场地震中隆起，这场地震历史上因沿该岛东海岸造成的破坏性海啸而闻名。珊瑚微环礁还记录了震间垂直变形，以每年到十年的分辨率，跨越每次地震前的几十年到一个多世纪。随着时间的推移，珊瑚的震间变形率发生了显着变化。在西默卢南部，1740 年至 1820 年间，震间沉降率较低，但在 1861 年破裂前的两到四十年，突然增加了 4 至 10 倍。这可能表明，巨型逆冲断层的完全耦合或深度锁定仅在大地震发生前几十年才开始。在巴尼亚克群岛，靠近2005年同震隆起与沉降的枢轴线附近，从1966年到1981年，持续的震间沉降转变为稳定隆起，这表明存在长达15年的慢滑移事件，滑移速度超过板块收敛速度的120%。
Fossil coral microatolls from fringing reefs above the great (MW8.6) megathrust rupture of 2005 record uplift during the historically reported great earthquake of 1861. Such evidence spans nearly the entire 400-km strike length of the 2005 rupture, which was previously shown to be bounded by two persistent barriers to seismic rupture. Moreover, at sites where we have constrained the 1861 uplift amplitude, it is comparable to uplift in 2005. Thus the 1861 and 2005 ruptures appear to be similar in both extent and magnitude. At one site an uplift around AD 1422 also appears to mimic the amount of uplift in 2005. The high degree of similarity among certain ruptures of this Nias–Simeulue section of the Sunda megathrust contrasts with the substantial disparities amongst ruptures along other sections of the Sumatran portion of the Sunda megathrust. At a site on the northwestern tip of Nias, reefs also rose during an earthquake in AD 1843, known historically for its damaging tsunami along the eastern coast of the island.The coral microatolls also record interseismic vertical deformation, at annual to decadal resolution, spanning decades to more than a century before each earthquake. The corals demonstrate significant changes over time in the rates of interseismic deformation. On southern Simeulue, interseismic subsidence rates were low between 1740 and 1820 but abruptly increased by a factor of 4–10, two to four decades before the 1861 rupture. This may indicate that full coupling or deep locking of the megathrust began only a few decades before the great earthquake. In the Banyak Islands, near the pivot line separating coseismic uplift from subsidence in 2005, ongoing interseismic subsidence switched to steady uplift from 1966 until 1981, suggesting a 15-year-long slow slip event, with slip velocities at more than 120% of the plate convergence rate.