Contributions of Ductile Shear Zones to Postseismic Deformation: Mechanical Advances and Data Assimilation

地震后的快速地震形变为了解地壳的力学行为提供了一个自然的机会。记录震后变形的大地测量数据集在过去几年中变得更加丰富和详细，但对这些数据集的许多研究仅限于记录特定机制与观测数据“一致”。各种各样的候选机制，已被提出作为负责任的过程证明了地震后变形的地球动力学的重要性，但我们目前缺乏对这一现象的理解。拟议的研究将结合联合收割机的建模框架，可以同时考虑多种流变行为与大地测量观测，通过数据同化算法。这种方法将确定与数据一致的过程范围，并排除其他过程，直接从大地测量数据中限制地壳的流变学。剪切带的形成和演化与发震断层耦合的模型将被开发，以解决地震后变形的源是分布式的还是本地化的，拟议的研究将有助于在地壳动力学过程的基础知识和我们的能力，以评估其对地震灾害的贡献。对剪切带形成的更好理解将对结构地质学和机械工程产生影响，其中局部化是一个永久的问题。这项工作的数据同化方面将有助于介绍一个广泛成功的科学方法断层力学问题。该项目代表了研究人员互补研究领域的合并，一个是地球动力学，另一个是大地测量学和数据同化。--

The rapid aseismic deformation that often follows earthquakes provides a natural opportunity to learn about the mechanical behavior of the Earth's crust. Geodetic data sets documenting postseismic deformation have become much more plentiful and detailed in the last few years, yet many studies of these data sets have been limited to documenting that a particular mechanism "is consistent with" the observed data. The wide variety of candidate mechanisms that have been proposed as the responsible process testifies to the importance of postseismic deformation in geodynamics, but also to our current lack of understanding of this phenomenon. The proposed study will combine a modeling framework that can simultaneously consider multiple rheological behaviors with the geodetic observations through a data assimilation algorithm. This approach, will identify the range of processes consistent with the data and rule out others, constraining the rheology of the crust directly from geodetic data. Models of shear zone formation and evolution coupled with a seismogenic fault will be developed to address whether the source of postseismic deformation is distributed or localized.The proposed study will contribute to basic knowledge of dynamical processes in the Earth's crust and to our ability to evaluate their contribution to earthquake hazards. The improved understanding of shear zone formation will have implications for structural geology and mechanical engineering, where localization is a permanent concern. The data assimilation aspect of this work will help introduce a widely successful scientific approach to fault mechanics problems. The project represents the merging of the complementary research fields of the investigators, geodynamics for one, and geodesy and data assimilation for the other.--