武汉大学许才军、江国焰团队的一项最新研究报道了压力扰动诱发地震破裂的数值模拟。相关论文发表在2024年3月19日出版的《大地测量与地球动力学》杂志上。

地下流体的注入可以引起断层内压力的增加，从而导致地震的发生。然而，控制压力扰动引起的地震破裂的因素仍然知之甚少。为了解决这一问题，基于滑移弱化规律，研究模拟了受压力偏移扰动的走滑断层地震成核和破裂的物理过程。

研究人员在模拟中考虑了背景应力、流体注入速率、受压区域面积、断层几何形状和断层摩擦系数等多种因素。模拟结果表明，控制破裂行为的不是剪应力与正应力的绝对值，而是剪应力与正应力的比值。在应力比大、注入速度快、受压面积大的情况下，地震容易以失控破裂的形式传播。

此外，长宽比较大的断层也有利于引发失控破裂。相反，断层走向、倾角和摩擦系数对破裂行为的影响较小。

附：英文原文

Title: Numerical simulations of earthquake rupture induced by pressure perturbation

Author: Bingquan Ren, Caijun Xu, Guoyan Jiang, Lei Yang

Issue&Volume: 2024/03/19

Abstract: The subsurface fluid injection can cause pressure increase within faults, leading to earthquake occurrences. However, the factors controlling earthquake rupture due to pressure perturbation remain poorly understood. To resolve this problem, we simulate the physical processes of earthquake nucleation and rupture on strike-slip faults perturbated by pressure migration based on the slip-weakening law. Multiple kinds of factors, including background stress, fluid injection rates, the area of the pressurized region, fault geometry, and fault friction coefficients, are considered in our simulations. Our simulation results reveal that the ratio of shear stress to normal stress rather than their absolute values controls the rupture behavior. With the large stress ratios, high injection rates, and large pressurized areas, earthquakes are prone to propagate as runaway ruptures. Additionally, faults with large aspect ratios of length to width are also favorable for causing runaway ruptures. In contrast, the factors of fault strike, dip angles and friction coefficients have minor influence on rupture behavior.

DOI: 10.1016/j.geog.2024.01.007

Source: https://www.sciencedirect.com/science/article/pii/S167498472400020X