南方科技大学徐世庆的课题组在研究中取得进展。他们的研究发现断层面形貌控制断层的断裂强度和破裂过程。2023年1月2日，国际知名学术期刊《自然—地球科学》发表了这一成果。

课题组研究人员在米级尺度的实验室断层上模拟地震旋回，以显示断层地形异质性程度的影响，特别是对宏观破坏所需的剪切力所表示的宏观峰值强度的影响。结果表明，由于宏观峰值强度降低，断层非均质性减弱，产生了比相对不均匀断层更大的应力降;非均质性较弱的断裂以亚剪切速度传播，而非均质性较强的断裂则具有较宽的破裂速度范围，包括慢滑和超剪切破裂。这些结果揭示了断层地形的非均质性如何影响破裂起始时的宏观峰值强度和破裂扩展过程中的应力降，这对认识天然断层和地震具有重要意义。

据悉，断层很少是完全平滑的，其地形起伏来自于沿断层表面的凹凸不平的分布。由于缺乏实地观测，断层表面地形对断层强度和地震震源性质的影响的理解受到了限制。

附：英文原文

Title: Fault strength and rupture process controlled by fault surface topography

Author: Xu, Shiqing, Fukuyama, Eiichi, Yamashita, Futoshi, Kawakata, Hironori, Mizoguchi, Kazuo, Takizawa, Shigeru

Issue&Volume: 2023-01-02

Abstract: Faults are rarely completely smooth, with topographic undulations coming from the distribution of asperities along the fault surface. Understanding the effects of fault surface topography on fault strength and earthquake source properties has been limited due to a lack of in situ observations in the field. Here we use simulated earthquake cycles on metre-scale laboratory faults to show the effects of the degree of fault topographic heterogeneity, especially on macroscopic peak strength represented by the shear force required to commence macroscopic failure. Our results demonstrate that the less heterogeneous fault is weaker, due to its lower macroscopic peak strength, and produces a larger stress drop on average than the more heterogeneous fault. Rupture along the less heterogeneous fault tends to propagate at subshear speed while the more heterogeneous fault accommodates a wider range of rupture speeds, including slow slip and supershear rupture. These results reveal how fault topographic heterogeneity affects macroscopic peak strength at rupture initiation and stress drop during rupture propagation, which has important implications for understanding natural faults and earthquakes.

DOI: 10.1038/s41561-022-01093-z

Source: https://www.nature.com/articles/s41561-022-01093-z