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的顶部，沉积盆地可以捕获、集中和放大地震能量。强地面运动的预测是至关重要的，在这些地区，以防止在未来的大事件的生命和财产损失。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是地面概念动力学3D数值模拟方面的专家。在这里，PI联合努力，在大洛杉矶交叉验证这些方法。他们利用环境噪声和过去的小地震数据，在南圣安德烈亚斯断层上创建了一套大型地震（6.5至7.8级）。模拟允许评估是否潜在的地质结构可以通道地震波，从而强烈放大地面运动。这个为期2年的项目将有助于减轻加州南部的地震危险。研究所采用的方法可应用于地质环境相若的其他市区。该项目还支助了一名早期职业女科学家，并培训了三名研究生，其目标是确定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。该项目将南加州作为天然实验室。其他大都市地区，如东京、墨西哥城、西雅图、湖城和雅加达，也受到类似的危害。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度界限，ii）检查增强地面运动的路径和源效应之间的耦合，以及iii）评估非线性效应对未来地面运动的影响程度。该项目的新奇在于理论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知识价值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.