Large earthquake ground‐motion simulations in 3D Earth models provide constraints on site‐specific shaking intensities but have suffered from limited frequency resolution and ignored site response in soft soils. We report new regional‐scale 3D simulations for moment magnitude 7.0 scenario earthquakes on the Hayward Fault, northern California with SW4. Simulations resolved significantly broader band frequencies (0–10 Hz) than previous studies and represent the highest resolution simulations for any such earthquake to date. Seismic waves were excited by a kinematic rupture following Graves and Pitarka (2016) and obeyed wave propagation in a 3D Earth model with topography from the U.S. Geological Survey (USGS) assuming a minimum shear wavespeed, VSmin⁠, of 500 m/s⁠. We corrected motions for linear and nonlinear site response for the shear wavespeed, VS⁠, from the USGS 3D model, using a recently developed ground‐motion model (GMM) for Fourier amplitude spectra (Bayless and Abrahamson, 2018, 2019a). At soft soil locations subjected to strong shaking, the site‐corrected intensities reflect the competing effects of linear amplification by low VS material, reduction of stiffness during nonlinear deformation, and damping of high frequencies. Sites with near‐surface VS of 500 m/s or greater require no linear site correction but can experience amplitude reduction due to nonlinear response. Averaged over all sites, we obtained reasonable agreement with empirical ergodic median GMMs currently used for seismic hazard and design ground motions (epsilon less than 1), with marked improvement at soft sedimentary sites. At specific locations, the simulated shaking intensities show systematic differences from the GMMs that reveal path and site effects not captured in these ergodic models. Results suggest how next generation regional‐scale earthquake simulations can provide higher spatial and frequency resolution while including effects of soft soils that are commonly ignored in scenario earthquake ground‐motion simulations.

中文翻译：

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北加利福尼亚州海沃德断层的Mw 7地震的区域规模3D地面运动模拟，解决了0-10 Hz的频率并包括了场地响应校正

3D地球模型中的大型地震地面运动模拟对特定地点的震动强度提供了限制，但在有限的频率分辨率下以及在软土中忽略了地点响应时都遇到了麻烦。我们用SW4报告了在加利福尼亚北部海沃德断层发生的7.0级情景地震的新区域级3D模拟。与以前的研究相比，该模拟方法能分辨出更宽的频带频率（0-10 Hz），代表了迄今为止任何此类地震的最高分辨率模拟。地震波在Graves和Pitarka（2016）之后因运动破裂而被激发，并服从美国地质调查局（USGS）地形的3D地球模型中的波传播，假设最小剪切波速VSmin⁠为500 m / s 我们针对剪切波速校正了线性和非线性部位响应的运动，来自USGS 3D模型的VS⁠，使用最近开发的地面运动模型（GMM）进行傅立叶振幅谱分析（Bayless和Abrahamson，2018，2019a）。在经受强烈震动的软土位置，经过现场校正的强度反映了低VS材料引起的线性放大，非线性变形过程中的刚度降低以及高频阻尼的竞争效应。近地表VS为500 m / s或更高的站点不需要进行线性站点校正，但由于非线性响应而会出现幅度减小的情况。在所有站点上取平均值，我们与目前用于地震危险和设计地面运动（ε小于1）的经验遍历中值GMM取得了合理的一致，软沉积站点的显着改善。在特定位置，模拟的震动强度显示了与GMM的系统差异，GMM揭示了这些遍历模型未捕获的路径和部位效应。结果表明，下一代区域规模的地震模拟如何提供更高的空间和频率分辨率，同时还包括在情景地震地震动模拟中通常被忽略的软土的影响。