Far-field tsunami hazard from mega-thrust earthquakes in the Indian Ocean
Far-field tsunami hazard from mega-thrust earthquakes in the Indian Ocean
复制标题
印度洋特大逆冲地震造成的远场海啸危险
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
C. Synolakis
中科院分区：
文献类型：
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作者：
E. Okal;C. Synolakis
摘要我们评估了远场海啸灾害在印度洋盆地的基础上，在盆地周围的主要地震带可能发生的特大地震的十个案例研究的流体动力学模拟。它们代表了地震破裂的最坏情况，沿着历史记录中支持大地震的孕震断层的全部范围。在一系列的数值实验中，在2004年苏门答腊海啸的源参数被允许一个接一个地变化，同时保持地震矩和断层方向不变，我们的文件，远场海啸振幅的主要模式是非常强大的名义上的变化，如震源深度，准确的质心位置，断层面上的滑移分布等参数。这些结果验证了对未来潜在地震的案例场景进行建模的概念，根据定义，这些地震的震源不精确。我们考虑位于2004年苏门答腊-安达曼断裂的末端的震源，即沿着苏门答腊南部海岸和安达曼-缅甸省;沿着巴基斯坦和伊朗的Makran海岸;以及沿着爪哇南部海岸，在那里发生大的板间逆冲地震的可能性不能完全排除。我们的流体动力学模拟的结果表明，在印度洋盆地的最大振幅的分布主要是由源的方向性的经典效应，此外，通过折射和聚焦沿着测深功能。因此，该盆地的许多省份可能受到比2004年更大的海啸幅度的威胁。这一模式在东非沿海沿着，从索马里到南非（包括南非），马达加斯加和马斯卡林群岛，特别是在南苏门答腊发生与1833年地震相当甚至可能更大的地震的情况下，人们普遍认为，由于2004年和2005年的断裂向西北方向转移了应力，甚至可能是在2007年本库鲁地震之后。
SUMMARY We evaluate far-field tsunami hazard in the Indian Ocean Basin based on hydrodynamic simulations of ten case studies of possible mega earthquakes at the major seismic zones surrounding the basin. They represent worst-case scenarios of seismic rupture along the full extent of seismogenic faults having supported large earthquakes in the historical record. In a series of numerical experiments in which the source parameters of the 2004 Sumatra tsunami are allowed to vary one by one, while keeping the seismic moment and the fault orientation unchanged, we document that the main patterns of far-field tsunami amplitudes are remarkably robust with respect to nominal variations in such parameters as hypocentral depth, exact centroid location, and slip distribution on the fault plane. These results validate the concept of modelling case scenarios of potential future earthquakes whose source is by definition imprecise. We consider seismic sources located at the extremities of the 2004 Sumatra‐Andaman rupture, namely along the southern coast of Sumatra and in the Andaman‐Myanmar province; along the Makran coast of Pakistan and Iran; and also along the southern coast of Java, where the possibility of a large interplate thrust earthquake cannot be entirely dismissed. The results of our hydrodynamic simulations indicate that the distribution of maximum amplitudes in the Indian Ocean Basin is primarily controlled by the classical effect of source directivity, and additionally by refraction and focusing along bathymetric features. As a result, many provinces in the basin could be threatened by higher tsunami amplitudes than in 2004. This pattern is particularly important along the coast of East Africa, from Somalia to and including South Africa, in Madagascar and the Mascarene Islands, especially under a South Sumatra scenario involving an earthquake comparable to, or even possibly larger than, the 1833 event, whose epicentral area is widely believed to be under enhanced seismic risk as a result of stress transfer from the 2004 and 2005 ruptures to the northwest, possibly even in the wake of the 2007 Bengkulu earthquakes.