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Continuum of earthquake rupture speeds enabled by oblique slip
Nature Geoscience ( IF 18.3 ) Pub Date : 2020-11-09 , DOI: 10.1038/s41561-020-00654-4
Huihui Weng , Jean-Paul Ampuero

Earthquake rupture speed can affect ground shaking and therefore seismic hazard. Seismological observations show that large earthquakes span a continuum of rupture speeds, from slower than Rayleigh waves up to P-wave speed, and include speeds that are predicted to be unstable by two-dimensional theory. This discrepancy between observations and theory has not yet been reconciled by a quantitative model. Here we present numerical simulations that show that long ruptures with oblique slip (both strike-slip and dip-slip components) can propagate steadily at various speeds, including those previously suggested to be unstable. The obliqueness of slip and the ratio of fracture energy to static energy release rate primarily control the propagation speed of long ruptures. We find that the effects of these controls on rupture speed can be predicted by extending the three-dimensional theory of fracture mechanics to long ruptures with oblique slip. This model advances our ability to interpret supershear earthquakes, to constrain the energy ratio of faults based on observed rupture speed and rake angle, and to relate the potential rupture speed and size of future earthquakes to the observed slip deficit along faults.



中文翻译:

斜滑使地震破裂速度连续

地震破裂速度会影响地面震动,因此会造成地震危险。地震观测表明,大地震的破裂速度是连续的,从比瑞利波慢到P波速,并包括二维理论所预测的不稳定速度。观测值与理论之间的这种差异尚未通过定量模型得到解决。在这里,我们提供的数值模拟表明,带有倾斜滑移的长裂缝(走滑和倾滑分量)都可以各种速度平稳传播,包括先前建议的不稳定速度。滑移的倾斜度和裂缝能量与静态能量释放速率的比值主要控制长裂缝的传播速度。我们发现,这些控制对破裂速度的影响可以通过将断裂力学的三维理论扩展到具有倾斜滑移的长破裂来预测。该模型提高了我们解释超剪切地震的能力,可以基于观测到的破裂速度和前倾角来限制断层的能量比,并将未来地震的潜在破裂速度和大小与沿断层观测到的滑移赤字联系起来。

更新日期:2020-11-09
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