Improving Earthquake Forecasting and Seismic Hazard Analysis Through Extreme-Scale Simulations

地震产生于复杂的、跨时间尺度的多尺度相互作用，时间尺度从几毫秒到数百万年不等，在活动断层系统中很难观察到。大规模的基于物理的地震模拟是必不可少的科学工具，可以用来更好地理解这些危险的自然现象。该项目将开发基于物理的模拟蓝海地震的规范，并应用这些模拟能力来改进现有的灾害分析方法。蓝水系统的大规模计算和数据管理能力将允许该项目开发和测试地震模型，以更真实的方式捕获物理，并以更精细的分辨率和更高的频率运行模拟。结果将更好地量化地震灾害及其不确定性。该项目将使用数值实验和大规模模拟来推进基于物理的概率地震危险性分析（PSHA）方法，以增加震源物理、非弹性和地质非均质性当前表示的尺度范围。具体而言，该研究项目将致力于实现七个计算目标，以提高我们对地震过程的理解，并推进基于物理的PSHA:(1)开发经验校准的基于物理的地震预报。(2)开发一个统计上充分，但减少的断裂集，代表新的统一加州地震断裂预报。(3)实现一种新的基于动态破裂的运动学震源模型，以计算高达每秒8次的地面运动。(4)评价以往模拟中观测到的盆地连通性现象，以确定在低地震频率下波导建模的重要性。(5)研究和表征材料和震源模型对地面运动模拟精度的影响。(6)验证和校准模拟中使用的流变模型。(7)对脆弱堤防进行物理灾害能力测试。本研究的目标是改进地震过程的物理表征和模拟地震的确定性代码，这将改善美国的PSHA实践，并使世界范围内的地震系统科学受益。

Earthquakes emerge from complex, multiscale interactions across time scales that range from milliseconds to millions of years within active faults systems that are incredibly difficult to observe. Large-scale physics-based earthquake simulations are essential scientific tools that can be used to better understand these hazardous natural phenomena. This project will develop physics-based codes for simulating earthquakes on Blue Waters and apply these simulation capabilities to improve existing hazard analysis methods. The very large scale computing and data management capabilities of the Blue Waters system will allow the project to develop and test earthquake models that capture physics in a more realistic manner, and to run simulations at finer resolutions and higher frequencies. The results will better quantify seismic hazards and their uncertainties. This project will advance physics-based probabilistic seismic hazard analysis (PSHA) methods using numerical experimentation and large-scale simulations to increase the scale range in current representations of source physics, anelasticity, and geologic heterogeneity. Specifically, the research project will work towards seven computational objectives defined to improve our understanding of earthquake processes and advance physics-based PSHA: (1) Develop an empirically-calibrated physics-based earthquake forecast. (2) Develop a statistically sufficient, but reduced, rupture set representative of the new Unified California Earthquake Rupture Forecast. (3) Implement a new dynamic-rupture based kinematic source model to compute ground motions up to 8 cycles per second. (4) Evaluate the basin connectivity phenomenon observed in previous simulations to establish the importance of waveguide modeling at low seismic frequencies. (5) Investigate and characterize the influence of material and source models on the accuracy of ground motion simulations. (6) Validate and calibrate the rheological models used in simulations. (7) Test the physics-based hazard capabilities on a vulnerable embankment dam. The goal of this research is to improve the physical representations of earthquake processes and the deterministic codes for simulating earthquakes, which will improve PSHA practice in the United States and benefit earthquake system science worldwide.