Collaborative Research: Cross-Validation of Empirical and Physics-based ground motion predictions

许多人口稠密的地区，如东京、西雅图和洛杉矶，都位于能够产生大地震的活动板块边界附近。这些城市通常建在沉积盆地顶部，沉积盆地会捕获、集中和放大地震能量。在这些地区，强烈地面震动的预测对于防止未来重大事件中的生命和财产损失至关重要。 PI Denolle 开创了一种新的经验方法，该方法使用地震环境噪声（例如海浪产生的噪声）来预测大地震地面运动。 PI Olsen 是基础概念动力学 3D 数值模拟方面的专家。在这里，PI 共同努力在大洛杉矶地区交叉验证这些方法。他们利用环境噪声和过去的小型地震数据在圣安德烈亚斯断层南部创建了一系列大型地震（震级 6.5 至 7.8 级）。模拟可以评估底层地质结构是否可能引导地震波，从而强烈放大地面运动。这个为期两年的项目将有助于减轻南加州的地震灾害。 PI 的方法可应用于具有类似地质背景的其他城市地区。该项目还支持一名职业生涯早期的女科学家，并为三名研究生提供培训。该项目的目标是表征地震波导放大与震源方向性放大之间的耦合效应。这种效应可能会增强沉积盆地的震动强度。该项目利用南加州作为天然实验室。其他大城市地区，如东京、墨西哥城、西雅图、盐湖城和雅加达，也面临着类似的危害。在这里，该团队创新地使用了两种最先进的地面运动预测方法之间的交叉验证：环境噪声虚拟地震方法和 3D 动态模拟。这种交叉验证允许 i) 建立两种方法的置信界限，ii) 检查增强地震动的路径效应和源效应之间的耦合，以及 iii) 评估非线性效应对未来地震动的程度。该项目的新颖之处在于理论地震学和观测地震学的独特结合。在这项工作中，将利用从密集阵列（包括宽带和节点地震仪器）新收集的数据。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优点和更广泛的影响审查标准进行评估，被认为值得支持。

Many densely populated areas such as Tokyo, Seattle, and Los Angeles are located near active plate boundaries capable of producing large earthquakes. These cities are often built on top of sedimentary basins which trap, focus and amplify earthquake seismic energy. Prediction of strong ground motions is critical in these areas to prevent the loss of life and property in future large events. PI Denolle pioneered a new empirical approach which uses seismic ambient noise, for example generated by ocean waves, to predict large earthquake ground motions. PI Olsen is an expert in 3D numerical simulations of ground-notion dynamics. Here, the PIs join effort to cross-validate these approaches in the greater Los Angeles. They use ambient noise and small past-earthquake data to create a suite of large scenario earthquakes (magnitude 6.5 to 7.8) on the southern San Andreas fault. The simulations allow evaluating whether the underlying geological structure may channel earthquake waves and thereby strongly amplify the ground motions. This 2-year project will help mitigating seismic hazards in southern California. The PIs' methodology can be applied to other urban areas located in similar geological context. The project also supports an early career female scientist and provides training to three graduate students.The goal of the project is to characterize the coupling effect between the amplification due to seismic waveguides and that due to source directivity. This effect may enhance shaking intensity in sedimentary basins. The project uses southern California as a natural laboratory. Other large metropolitan areas, such as Tokyo, Mexico City, Seattle, Salt Lake City and Jakarta, are subjected to similar hazards. Here, the team innovates in using cross-validation between two state-of-the-art ground-motion prediction approaches: the ambient-noise Virtual Earthquake Approach and 3D dynamic simulations. This cross-validation allows i) establishing bounds of confidence in the two methods, ii) examining the coupling between path and source effects in enhancing ground motion, and iii) evaluating the extent of nonlinear effects on future ground motions. The novelty of the project is the unique combination of theoretical and observational seismology. In this effort, newly collected data from dense arrays including both broadband and nodal-seismic instruments will be exploited.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.