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
