RUI: Collaborative Research: Quaternary Deformation in the Cascades Foothills and Southern Puget Lowland, Washington

小行星9627856 华盛顿的普吉特低地位于卡斯卡迪亚会聚边缘的弧前区域，在这里，胡安达富卡板块斜向会聚在北美板块之下。伴随的变形发生在沿着俯冲板块边界或贝尼奥夫带，以及横跨北方加州、俄勒冈州、华盛顿和西南部不列颠哥伦比亚省的上部（北美）板块的广阔复杂区域。已经提出了几个模型来解释在卡斯卡迪亚边缘第四纪变形，但目前的现场数据是不够的，以评估这些模型。该项目将研究如何在西雅图附近的活动断层滑动继续向南。这项工作是一个试点项目，以确定表面暴露和地震数据是否足以测试一个模型，该模型表明，西雅图断层是一个综合的，区域性的逆冲系统的一部分，在整个普吉特低地。如果成功，结果将提供一个非常需要的模型框架，了解这种transstensional构造环境，这也将提供一个重点的风险评估。

9627856 Umhoefer The Puget Lowland, Washington, is in the fore-arc region of the Cascadia convergent margin, where the Juanda Fuca plate is obliquely converging beneath the North American plate. Associated deformation occurs along the subducting plate boundary or Benioff zone and also in a wide, complex region of the upper (North American) plate extending across Northern California, Oregon, Washington and Southwestern British Columbia. Several models have been proposed to explain Quaternary deformation in the Cascadia margin, but present field data is inadequate to evaluate these models. This project will examine how slip on an active fault in the vicinity of Seattle continues to the South. The work is a pilot project to determine if surface exposures and seismic data will be adequate to test a model that suggests that the Seattle fault is part of an integrated, regional thrust system under the entire Puget-Lowland. If successful, the results will provide a much needed model framework for understanding this transtensional tectonic environment, which will also provide a focus for risk assessment.