Investigation of Surface Deformation at Subduction Zones using a Finite Plate Model

俯冲带的地表变形通常被解释为俯冲板块和上覆板块之间逆冲边界上的运动。弹性半空间位错（EHSD）模型经常用于从地面大地测量观测推断断层上的滑动分布，并根据断层的哪些部分被完全或部分锁定来评估地震危险性。这些模型因其简单而吸引人，但假设所有地表变形都是由于嵌在均匀弹性半空间中的断层上的运动导致一些不现实的行为。而不是考虑整个系统，这个项目将只考虑覆盖板的一部分，在感兴趣的时间段内表现出弹性。地表变形的发生是由于沿逆冲断层边界和沿有限弹性区域（上覆板块）底部施加的应力变化或速率造成的。与EHSD模型相比，该方法提供了一种更有希望的理解俯冲带物理性质的方法，并且隐含的假设更少。利用该方法反演的结果将与利用EHSD模型反演的结果进行对比。调查人员将首先检查俄勒冈州和华盛顿州的卡斯卡迪亚俯冲带，以及阿拉斯加的基奈半岛。其他研究地区将包括日本、苏门答腊、喜马拉雅山和新西兰。研究结果对断层摩擦研究、地震危险性研究、板块驱动力和阻力的认识具有重要的指导意义。

Williams 0106798 Surface deformation at subduction zones is generally interpreted in terms of movement on the thrust boundary between the subducting slab and the overriding plate. Elastic half-space dislocation (EHSD) models are frequently used to infer a slip distribution on the fault from surface geodetic observations and seismic hazard is evaluated in terms of which portions of the fault are fully or partially locked. These models are appealing because of their simplicity, but the assumption that all surface deformation is due to movement on a fault embedded in a homogeneous elastic half-space leads to some unrealistic behavior. Rather than considering the entire system, this project will consider only the portion of the overriding plate that behaves elastically over the time period of interest. Surface deformation occurs as a result of stress changes or rates applied along the thrust fault boundary and along the base of a finite elastic region (the overriding plate). This approach offers a more promising means of understanding the physics of subduction zones and makes fewer implicit assumptions than do EHSD models. Inversion results using this method will be compared and contrasted with those using EHSD models. The investigators will initially examine the Cascadia subduction zone in Oregon and Washington, and the Kenai Peninsula in Alaska. Additional study areas will include Japan, Sumatra, the Himalayas, and New Zealand. The results of this study should have important implications in fault friction studies and earthquake hazard research, and in understanding plate driving and resistive forces.