Three-dimensional modeling of interseismic, co-seismic, and post-seismic deformation in Taiwan

目前，地壳动力学缺乏内部一致的连续体模型来解释整个地震周期（包括震间期、同震期和震后期）的观测结果，同时与地形起伏分布等地质中较长时间尺度的应变表现一致。台湾地震周期的研究在某种程度上是独特的，因为在地震周期的所有三个阶段都有高应变率，并且在1999年7.6 Mw集集地震之前，期间和之后都有非凡的大地测量覆盖。此外，主要断层结构的几何形状现在已经相对为人所知，并且对材料特性的三维变化的合理可靠的估计正在变得可行。我们的目标是建立一个单一的模型，解决现有模型与各自数据集的不匹配问题，同时试图推导出一个内部一致的描述，该描述可以在涉及山脉建设的时间尺度上工作。我们大致按以下顺序处理以下任务：1)使用三维弹性结构和新的断层几何形状修正1999年7.6 Mw集集地震的弹性同震和余震模型。这些模型将考虑所有可用的GPS、SAR和光学大地测量数据。2)构建一套初始的二维粘弹塑性模型，以直观地了解自旋问题以及不同边界条件的影响。3)构建三维震后和震间粘弹塑性模型。4)考虑对流变性的观测约束热控制，以及侵蚀在改变山脉长期演变中的作用。该项目旨在开发一个内部一致的地球动力学模型，跨越从地震到造山的时间尺度。它利用并贡献了最先进的大地测量和建模工具，以解决主要断层和周围介质中横向变化流变结构的固有难题。作为该项目的一部分开发的所有分析工具都向公众发布。这项活动是与美国和台湾科学家更大规模合作的一部分。我们期望这一努力将有助于更好地了解台湾的地震潜力。

Currently, crustal dynamics lacks internally consistent continuum models that explain observations spanning the entire earthquake cycle including, the interseismic, coseismic, and postseismic periods, while being consistent with the longer timescale strain manifest in the geology, such as the distribution of topographic relief. Studies of the earthquake cycle in Taiwan are somewhat unique because of the high strain rates over all three phases of the earthquake cycle and the extraordinary geodetic coverage before, during, and after the 1999 Mw 7.6 Chi-Chi earthquake. In addition the geometry of the primary faults structures is now relatively well known and reasonably reliable estimates of 3D variations in material properties are becoming available.Our effort aims to build a single model that addresses both the misfits of existing models to their respective data sets, while at the same time trying to derive an internally consistent description that works up to time scales involving the building of the mountains. We are addressing the following tasks in approximately this order: 1) Revise elastic coseismic and afterslip models for the 1999 Mw 7.6 Chi-Chi earthquake using 3D elastic structures and a new fault geometry. These models will consider all available GPS, SAR, and optical geodetic data. 2) Construct an initial suite of 2-D visco-elasto-plastic models to develop intuition for spin-up issues, as well as effects of different boundary conditions. 3) Construct 3D post-seismic and interseismic visco-elasto-plastic models. 4) Consider observationally constrained thermal controls on rheology - as well as the role of erosion in modifying the long-term evolution of mountain range.This projects aims to develop an internally consistent geodynamic model spanning time scales from earthquakes up to that of mountain building. It takes advantage of, and contributes to, state-of-the-art geodetic and modeling tools to address the inherently difficult problem of laterally varying rheological structures both on major faults and in the surrounding media. All analysis tools being developed as part of this project are released to the public. This activity forms part of a larger collaboration with scientists in the U.S. and Taiwan. We expect that this effort will result in a better understanding of seismic potential in Taiwan.