Reconstruction of the slip distributions in historical earthquakes on the Sunda megathrust, W. Sumatra
Reconstruction of the slip distributions in historical earthquakes on the Sunda megathrust, W. Sumatra
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西苏门答腊巽他巨型逆冲断层历史地震滑动分布的重建
DOI：
10.1093/gji/ggv195
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发表时间：
2015
影响因子：
2.8
通讯作者：
Nic Bhloscaidh M
中科院分区：
文献类型：
--
作者：
Nic Bhloscaidh M
大地震滑动的空间异质性反演通常只适用于现代仪器记录的事件。活动性断层的应力重建是地震危险性评估的重要组成部分，通常基于一两次仪器反演和一些有关历史地震活动的半定量信息。在这里，我们开发了一种新的贝叶斯蒙特卡罗反演方法，用于稀疏的，大不确定性的数据，如许多历史地震。我们用它从200年的古大地测量数据中重建了巽他大逆冲断层上两次大地震的滑动，这些数据记录在弧前岛屿的珊瑚微环礁的地层学中。该技术是基于许多滑移分布的随机正演模拟，这些分布受滑移场中观测到的分形尺度的约束。用一组静力弹性格林函数来估计每次试滑分布所引起的珊瑚位置的垂直位移。滑移的后验期望值及其方差是由试验滑移的平均值获得的，并根据它们再现珊瑚位移的能力进行加权。我们成功地在合成滑动分布上测试了该方法，然后将其应用于最近仪器记录的事件中的滑动重建。然后，我们反演了1797年和1833年苏门答腊岛西部明打威群岛下的大型逆冲事件。与近年来地震的滑动分布相比较，我们的结果明确表明，该序列与经典的特征地震模型不一致；地震倾向于逐渐地将活动断层分割，而不是重复地破坏其中的一部分。结果表明，具有非均匀初始应力的断层均质加载足以解释巽他巨型逆冲构造明打威段的观测结果；例如，材料性质的时间依赖性是没有必要的。此外，我们推测破裂过程中即使少量的非线性也会确保任何镶嵌序列不会重复，即使在很长一段时间内。这种方法可以用来结合其他的历史信息，比如海啸上升的记录和Mercalli强度的估计。最后，我们建议基于长期滑动历史的应力重建可能有助于确定未来地震的可能位置。
Spatially heterogeneous inversions for the slip in major earthquakes are typically only available for modern, instrumentally recorded events. Stress reconstructions on active faults, which are potentially vital elements of earthquake hazard assessment, are usually based on one or two instrumental inversions and some semi-quantitative information concerning historical seismic activity. Here we develop a new Bayesian Monte Carlo inversion method for sparse, large uncertainty data, such as is available for many historical earthquakes. We use it to reconstruct the slip in two great historical earthquakes on the Sunda megathrust, from 200 yr of paleogeodetic data recorded in the stratigraphy of coral microatolls on the forearc islands. The technique is based on the stochastic forward modelling of many slip distributions, which are constrained by the observed fractal scaling in the slip field. A set of static elastic Green's functions is used to estimate the vertical displacement at the coral locations resulting from each trial slip distribution. The posterior expected value of the slip and its variance are obtained from the average of the trial slips, weighted by their ability to reproduce the coral displacements. We successfully test the method on a synthetic slip distribution, before applying it to reconstruct the slip in a recent, instrumentally recorded event. We then invert for the great 1797 and 1833 megathrust events under the Mentawai Islands west of Sumatra. When compared with the slip distributions in recent earthquakes, our results unambiguously indicate that the sequence is not consistent with the classic characteristic earthquake model; earthquakes tend to incrementally tessellate the active fault plane rather than repeatedly breaking a segment of it. The results indicate that homogeneous loading of a fault with heterogeneous initial stress is enough to explain the observations on the Mentawai segment of the Sunda megathrust; no time dependence of material properties, for example, is necessary. Furthermore, we speculate that even small amounts of nonlinearity in the rupture process would ensure that any tessellating sequence will not be repeated, even over very long times. This method could be adapted to incorporate other historical information, such as records of tsunami run up and Mercalli Intensity estimates. Finally, we suggest that reconstruction of stress based on long-term slip histories may prove useful in identifying the possible locations of future earthquakes.
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苏门答腊俯冲带：锁定断层带延伸至地幔的案例
DOI：
--
发表时间：
2004
期刊：
影响因子：
--
作者：
M. Simoes;J. Avouac;R. Cattin;P. Henry
通讯作者：
P. Henry
影响因子：
18.3
作者：
Lorito, S.;Romano, F.;Piatanesi, A.
通讯作者：
Piatanesi, A.
巽他弧的地震历史和地震构造
影响因子：
--
作者：
K. Newcomb;W. Mccann
通讯作者：
W. Mccann
影响因子：
3
作者：
Y. Okada
通讯作者：
Y. Okada
根据珊瑚微环礁推断的 1797 年和 1833 年苏门答腊巨型逆冲断层大地震的震源参数
影响因子：
--
作者：
D. Natawidjaja;K. Sieh;M. Chlieh;J. Galetzka;B. Suwargadi;Hai Cheng;R. Edwards;J. Avouac;S. Ward
通讯作者：
S. Ward