We present a nonergodic framework for probabilistic seismic‐hazard analysis (PSHA) that is constructed entirely of deterministic, physical models. The use of deterministic ground‐motion simulations in PSHA calculations is not new (e.g., CyberShake), but prior studies relied on kinematic rupture generators to extend empirical earthquake rupture forecasts. Fully dynamic models, which simulate rupture nucleation and propagation of static and dynamic stresses, are still computationally intractable for the large simulation domains and many seismic cycles required to perform PSHA. Instead, we employ the Rate‐State earthquake simulator (RSQSim) to efficiently simulate hundreds of thousands of years of M≥6.5 earthquake sequences on the California fault system. RSQSim produces full slip‐time histories for each rupture, which, unlike kinematic models, emerge from frictional properties, fault geometry, and stress transfer; all intrinsic variability is deterministic. We use these slip‐time histories directly as input to a 3D wave‐propagation code within the CyberShake platform to obtain simulated Fmax=0.5 Hz ground motions. The resulting 3 s spectral acceleration ground motions closely match empirical ground‐motion model (GMM) estimates of median and variability of shaking. When computed over a range of sources and sites, the variability is similar to that of ergodic GMMs. Variability is reduced for individual pairs of sources and sites that repeatedly sample a single path, which is expected for a nonergodic model. This results in increased exceedance probabilities for certain characteristic ground motions for a source–site pair, while decreasing probabilities at the extreme tails of the ergodic GMM predictions. We present these comparisons and preliminary fully deterministic physics‐based RSQSim–CyberShake hazard curves, as well as a new technique for estimating within‐ and between‐event variability through simulation.

中文翻译：

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迈向基于物理的非遍历PSHA：南加州的原型完全确定性地震危险性模型

我们为概率地震危险性分析（PSHA）提供了一个非遍历的框架，该框架完全由确定性的物理模型构成。在PSHA计算中使用确定性地面运动模拟并不是什么新鲜事（例如，Cyber​​Shake），但是先前的研究依靠运动破裂发生器来扩展经验地震破裂预报。对于大型模拟域和执行PSHA所需的许多地震周期，用于模拟破裂形核以及静态和动态应力的传播的全动态模型仍然在计算上难以处理。相反，我们使用速率状态地震模拟器（RSQSim）有效地模拟了加利福尼亚断层系统上数十万年的M≥6.5地震序列。RSQSim会为每次破裂生成完整的滑移时间历史记录，这与运动学模型不同，产生于摩擦特性，断层几何形状和应力传递；所有内在的变异性都是确定性的。我们将这些滑移时间历史直接用作Cyber​​Shake平台内3D波传播代码的输入，以获得模拟的Fmax = 0.5 Hz地面运动。由此产生的3 s频谱加速度地面运动与经验地面运动模型（GMM）估计的中值和抖动变化紧密匹配。当计算一系列来源和地点时，变异性与遍历GMM相似。对于重复采样一条路径的单个源和站点对的可变性降低了，这是非遍历模型所期望的。这导致源站点对的某些特征性地面运动的超标概率增加，同时降低了遍历GMM预测末尾的概率。我们将提供这些比较结果和基于物理的初步完全确定性的RSQSim–Cyber​​Shake危险曲线，以及一种通过模拟估算事件内和事件间变异性的新技术。