[论文解读] Theoretical constraints on tidal triggering of slow earthquakes

Yishuo Zhou, Ankit Gupta+5 more|arXiv (Cornell University)|Feb 6, 2026

earthquake and tectonic studies被引用 0

一句话总结

使用带有速率与状态摩擦的弹簧–块模型，分析潮汐样扰动如何在速滑衰减断层上触发滑动，识别无量纲控制参数和共振样放大条件。

ABSTRACT

Tidal stress is a globally acting perturbation driven primarily by the gravitational forcing of the Moon and the Sun. Understanding how tidal stresses can trigger seismic events is essential for constraining tectonic environments that are sensitive to small stress perturbations. Here, employing a spring-block with rate-and-state friction, we investigate tidal triggering on velocity-weakening stable sliding faults with stiffness slightly exceeding the critical stiffness. We first apply idealized step-like and boxcar normal stress perturbations to demonstrate a resonance-like amplification of slip rate when the perturbation period approaches the intrinsic frictional timescale of state evolution. Next, we perform nondimensional analyses and numerical simulations with harmonic tidal-like perturbations to identify the key parameters controlling tidal triggering and their admissible ranges. Triggered slip events are further characterized using physically interpretable quantities, including radiation efficiency and tidal phase. Our results show that even small stress perturbations can trigger periodic as well as complex slip events on stable sliding faults. The triggering behavior is primarily controlled by the normalized perturbation period and the normalized perturbation amplitude. An increase in the normalized period shifts event timing from the peak of tidal stress toward the peak of stress rate, whereas increasing the normalized amplitude promotes a transition from slow to fast events. The parameter space permitting triggered events suggests that the parameter which characterizes the instantaneous frictional strength of an interface, should not exceed tens to hundreds of kilopascals, and that the characteristic slip distance for frictional weakening is likely on the order of micrometers.

研究动机与目标

• 理解小型潮汐应力如何影响经历稳定滑动的区域内慢断层滑动的机制以提高认识。
• 研究速衰减断层对瞬时和周期性法向应力扰动的响应。
• 建立无量纲框架以识别支配潮汐触发的关键参数。
• 绘制在谐波（潮汐）强迫下可诱发可观测滑动事件的参数区间。

提出的方法

• 采用具有老化演化形式的带有速率-状态摩擦的弹簧–块模型。
• 使用阶跃、箱波形（boxcar）和谐波法向应力扰动来模拟断层响应。
• 对控制方程进行无量纲化以识别控制参数（R_ab、κ、N、P_σ、P_T）。
• 在参数空间内进行数值模拟以刻画触发条件。
• 分析共振样放大并将结果与观测量如相位和辐射效率等联系起来。

Figure 1 : Spring–block model under stress perturbations. The block slides with velocity $V$ under a constant normal stress $\sigma_{0}$ , subject to an imposed normal stress perturbation $\sigma_{\mathrm{p}}(t)$ and an applied shear stress perturbation $\tau_{\mathrm{p}}(t)$ . The elastic loading i

实验结果

研究问题

• RQ1 在什么条件下，小型潮汐样扰动可以在速滑衰减断层上触发滑动？
• RQ2 扰动幅度和持续时间如何影响滑动放大与时序？
• RQ3 哪些无量纲参数决定断层对周期性应力强迫的敏感性？
• RQ4 在稳定滑动断层的 RSF 框架中，如何产生共振样效应？
• RQ5 这些结果对解释潮汐触发的慢地震有何意义？

主要发现

• 在扰动时序与断层固有时间尺度共振时，能在稳定滑动、速率衰减的断层上触发滑动，且小应力扰动也可触发。
• 对于有限持续时间的扰动，出现共振样放大；最大滑动速度在特定扰动周期范围内可超过阶跃响应。
• 无量纲参数 P_σ 和 P_T，以及 R_ab、κ、N，控制触发行为以及慢事件向快事件的转变。
• 在允许触发事件的参数空间中，较小的瞬时摩擦强度 aσ_0 与弱化的微米级滑动距离 d_c 被提出。
• 该框架将触发与可观测的量（如辐射效率和潮汐相位）联系起来，并支持推广到其他时变扰动和 RSF 定律。

Figure 2 : Responses of slip velocity to step changes in normal stress. (a) Downward step change and (b) Upward step change. Red dashed and blue solid curves correspond to $|\Delta\sigma|=1~\mathrm{kPa}$ and $2~\mathrm{kPa}$ , respectively. The dark gray line with circles indicates the reference cas