CAREER: Integrating earthquake physics and source imaging while engaging the Hispanic community

该项目的主要研究目标是通过缩小理论和计算地震动力学与观测震源地震学之间的差距，同时显著促进两者的发展，了解地震破裂复杂性的来源及其对破坏性地面运动的影响。这项研究将理论和观测相结合，以提高从地震学数据中提取对地震破裂过程的可靠约束的能力。它提供了一个计算环境来解决悬而未决的问题，并提出关于地震物理学的可验证的假说。计算地震学的拟议发展通过合并两种能够处理真实几何和流变学的方法，通过将时空自适应技术应用于动态破裂问题，并通过将谱元素模拟能力扩展到地震周期的较长时间尺度，来处理地震动力学的多尺度方面。建议的观测发展在基于高频地震阵列数据反投影的震源成像技术中引入了多尺度信号分析的概念，并将这些结果与更传统的低频震源反演方法相结合。2011年日本东北9级特大地震是综合努力的一个主要焦点。理论和观测之间的协同活动通过真实的合成场景来表征震源成像中的不确定性，并通过在震源反演问题中整合足够的先验信息来缓解这些不确定性。该项目的教育和宣传活动促使拉美裔社区提高其关于地震过程的科学素养，以减少其对地震灾害的脆弱性。为此，为拉美裔媒体举办了定期讲习班，聘请了西班牙裔本科生暑期实习生，与社会科学家合作评估了拉美裔人口脆弱性的文化因素，开展了将地震灾害与拉美裔遗产联系起来的学校活动，并让南加州的拉美裔参与低成本的地震网络。此外，软件产品和相关培训材料被公开提供，研究成果被整合到研究生教学中。这项研究解决了地震科学中的一个突出挑战：解决和解释动态破裂的多尺度复杂性。该项目通过基于物理的模拟和基于数据的地震破裂成像之间的协同，将地震研究的两个不同方向--理论/计算地震物理学和观测地震学--结合在一起。这项研究加深了我们对动态断裂多尺度过程的一般理解，并为相关软件和分析工具提供了在其他学科中潜在的应用，例如用于评估非均质工程材料的可靠性。这些研究产品增强了快速反应的能力，以减轻全球地震的破坏性影响。该项目自然涉及国际合作。这些教育活动促进了地震学和社会科学之间的跨学科互动，并促进了拉美裔社区这一代表性不足的群体参与科学教育和研究，同时减少了其对自然灾害的脆弱性。

The main research goal of this project is to understand the origin of earthquake rupture complexity and its impact on destructive ground motions by narrowing the gap between theoretical and computational earthquake dynamics and observational earthquake source seismology, while significantly advancing both. This research integrates theory and observations to enhance the capacity to extract reliable constraints on earthquake rupture processes from seismological data. It provides a computational environment to address open questions and formulate testable hypothesis about the physics of earthquakes. The proposed developments in computational seismology tackle the multi-scale aspects of earthquake dynamics by consolidating two methods that can handle realistic geometries and rheologies, the spectral element method (SEM) and the discontinuous Galerkin method, by applying space-time adaptive techniques to dynamic rupture problems and by extending the SEM simulation capabilities to the longer time-scales of the earthquake cycle. The proposed observational developments introduce multi-scale signal analysis concepts in source imaging techniques based on back-projection of high-frequency seismic array data and integrate these results with more traditional source inversion approaches at lower frequencies. The 2011 M9 Tohoku (Japan) mega-earthquake is a main focus of the integrative efforts. Synergistic activities between theory and observations characterize the uncertainties in source imaging through realistic synthetic scenarios and mitigate those uncertainties by integrating adequate prior information in the source inversion problem. The education and outreach activities of this project engage the Hispanic community in enhancing its scientific literacy about earthquake processes, to reduce its vulnerability to seismic hazards. This is achieved by regular workshops for the Hispanic media, by engaging Hispanic undergraduate summer interns, by assessing in collaboration with social scientists the cultural factors of vulnerability in the Hispanic population, by developing school activities that link earthquake hazards and Hispanic heritage and by involving Latinos of Southern California in low-cost seismic networks. In addition, software products and related training materials are made openly available and the research results are integrated in graduate teaching.This research addresses an outstanding challenge in earthquake science: resolving and interpreting the multi-scale complexity of dynamic rupture. The project integrates two distinct directions of earthquake research, theoretical/computational earthquake physics and observational seismology, through synergy between physics-based simulation and data-based earthquake rupture imaging. This research improves our general understanding of multi-scale processes in dynamic fracture and provides related software and analysis tools with potential applications in other disciplines, e.g. for the assessment of the reliability of heterogeneous engineering materials. The research products enhance the capacity of rapid response to mitigate the destructive effects of earthquakes globally. The project naturally involves international collaborations. The educational activities foster inter-disciplinary interactions between seismology and social science, and foster the participation in scientific education and research of an underrepresented group, the Hispanic community, while reducing its vulnerability to natural hazards