Dynamics and Kinematics of North America -Juan de Fuca- Pacific Plate Interaction: Constraints from GPS Geodesy and Geophysical Modeling

描述北美大陆动力学的特征主要依赖于约束太平洋西北构造。太平洋西北部提供了在板块边界尺度上区分北美西部活动变形动力模式的关键约束。如果不了解这一地区，就无法准确理解圣安德烈亚斯体系、内华达山脉块体的夹带作用以及现代盆地和山脉伸展在板块相互作用和板块内构造中的作用。此外，Cascadia是测试和比较俯冲带地震间应变积累模型的世界级天然实验室，这些模型被广泛应用于其他俯冲带，但由于自然复杂性而无法进行此类测试。在公元1700年的俯冲带事件中，一个单一的、大震级的、相对简单的、边缘范围的破裂，独特的古地震约束使Cascadia成为研究300年地震间旋回中粘弹性与弹性变形模型的一个极好的案例。如此简单的系统，如此古老的系统，很少为人所知。继续进行大地测量学和地球物理模型研究的建议将对太平洋西北地区的地壳变形施加一级限制，在那里它们对俯冲带力学和大陆动力学以及板块驱动力具有直接影响。这些研究也直接支持了从普吉特海湾到俄勒冈州波特兰的城市走廊的地震风险评估。研究人员将完成PANGA速度场和位错建模，并继续运行连续的PANGA GPS网络。实现这些目标需要PANGA阵列的持续观测，将这些结果与美国西部其他变形阵列相结合，继续进行区域运动学和动力学建模研究，并完善最近的俯冲带动力学模型。这种方法可以很好地从区域长期应变场中解析叠加的地震间（弹性和粘弹性）俯冲应变场，从而解决运动学和动力学模型的问题。

EAR-0003483Miller Characterizing North American continental dynamics critically depends on constraining Pacific Northwest tectonics. The Pacific Northwest provides key constraints that differentiate dynamic models of active deformation in western North America at a plate boundary scale. The San Andreas system, entrainment of the Sierra Nevada block, and the role of modern Basin and Range extension in plate interaction and within-plate tectonics, cannot be accurately understood in ignorance of this region. Moreover, Cascadia is a global class natural laboratory for testing and comparing subduction zone interseismic strain accumulation models, models that are widely applied to other subduction zones where such testing is precluded by natural complexity. Unique paleoseismic constraints on a single, large-magnitude and relatively simple, margin-wide rupture of the 1700 A.D. subduction zone event make Cascadia an excellent case study of viscoelastic vs. elastic deformation models 300 years into the interseismic cycle. Rarely is such a simple system, of such vintage, so well known. The proposed continuation of geodetic and geophysical modeling studies will place first order constraints on crustal deformation in the Pacific Northwest, where they have direct implications for subduction zone mechanics and for continental dynamics, as well as for plate driving forces. These studies also directly support seismic risk evaluation in the urban corridor from Puget Sound to Portland, Oregon. The investigators will undertake completion of the PANGA velocity field and completion of dislocation modeling, as well as continued operation of the continuous PANGA GPS network. Meeting these goals requires ongoing observations by the PANGA array, setting these results results in the context of other western U.S. deformation arrays, continuing the regional kinematic and dynamic modeling studies, and refining recent models for subduction zone dynamics. This approach will resolve the superimposed interseismic (elastic and viscoelastic) subduction strain field from the regional secular stain field well enough to address the kinematic and dynamic models.