Early and persistent supershear rupture of the 2018 magnitude 7.5 Palu earthquake
Early and persistent supershear rupture of the 2018 magnitude 7.5 Palu earthquake
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DOI：
10.1038/s41561-018-0297-z
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发表时间：
2019-03-01
影响因子：
18.3
通讯作者：
Huang, Hui
中科院分区：
文献类型：
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作者：
Bao, Han;Ampuero, Jean-Paul;Huang, Hui
地震破裂传播的速度影响其能量平衡和地面震动的影响。超切变地震的动力学模型比横波的速度快，通常从亚切变速度开始，然后比埃舍尔比速度更快。在这里，我们提供了强有力的证据，证明2018年印度尼西亚帕卢7.5级地震的早期和持续的超剪切破裂速度低于埃谢尔比。远震数据的慢度增强反投影提供了破裂过程的清晰图像，沿着与合成孔径雷达和卫星光学图像的亚像素相关性推断的地表破裂轨迹一致的路径。尽管有很大的断层弯曲，但破裂从开始到结束的持续速度为4.1 km / s（-1）。远场瑞利马赫波的地震证据进一步证实了持续的超剪切速度。这次地震的不同寻常的特征揭示了断裂动力学和断层结构之间的联系。震源附近的断层粗糙度可以促进早期超剪切转变。在均匀介质中以意想不到的速度稳定破裂传播可能是由于低速损坏断裂带的存在。
The speed at which an earthquake rupture propagates affects its energy balance and ground shaking impact. Dynamic models of supershear earthquakes, which are faster than the speed of shear waves, often start at subshear speed and later run faster than Eshelby's speed. Here we present robust evidence of an early and persistent supershear rupture at the sub-Eshelby speed of the 2018 magnitude 7.5 Palu, Indonesia, earthquake. Slowness-enhanced back-projection of teleseismic data provides a sharp image of the rupture process, along a path consistent with the surface rupture trace inferred by subpixel correlation of synthetic-aperture radar and satellite optical images. The rupture propagated at a sustained velocity of 4.1 km s(-1) from its initiation to its end, despite large fault bends. The persistent supershear speed is further validated by seismological evidence of far-field Rayleigh Mach waves. The unusual features of this earthquake probe the connections between the rupture dynamics and fault structure. An early supershear transition could be promoted by fault roughness near the hypocentre. Steady rupture propagation at a speed unexpected in homogeneous media could result from the presence of a low-velocity damaged fault zone.