Contemporary Cascadia Deformation overDisparate Time Scales: Systematics of Slow Earthquakes and Fore-arc Impingement

利用全球定位系统（GPS）大地测量学进行的连续观测可以高精度地确定水平和垂直形变率及其在时间和空间上的变化。 该项目的重点是两个方面的目前GPS确定的四维形变场沿着卡斯卡迪亚收敛边缘在太平洋西北部。 首先，卡斯卡迪亚巨型逆冲断层瞬态事件的空间和时间分布正在调查。这部分研究的动机是基于PANGA网络分析的初步结果，这些结果表明，自1992年以来，太平洋西北部至少发生了8次MW 6.0（当量）的无声地震（持续数天至数月的无震滑动事件）。这些数据正在重新分析，使用主成分分析的结果被用于空间反演，以确定的时刻屈服，空间位置，和迁移的每个蠕变事件跨板块界面。其次，运动学的迁移大陆弧前（西部华盛顿），因为它遇到了一个刚性的扶壁（温哥华岛）正在审查的速度场分析从PANGA阵列，和发展的断层几何形状和力学块模型的板内变形的卡斯卡迪亚边缘和普吉特低地。

Continuous observations using Global Positioning System (GPS) geodesy yield high-precision determination of horizontal and vertical deformation rates and their variation in time and space. This project focuses on two aspects of the current GPS-determined four-dimensional deformation field along the Cascadia convergent margin in the Pacific Northwest. First, the spatial and temporal distribution of transient events on the Cascadia megathrust is being investigated. This part of the study is motivated by preliminary results that indicate at least 8 silent earthquakes (aseismic slip events lasting days to months) with Mw 6.0 (equivalent) occurred in the Pacific Northwest since 1992 based on analysis of the PANGA network. The data are being reanalyzed using principal component analysis the results of which are used for spatial inversion to determine the moment yield, spatial locations, and migration of each creep event across the plate interface. Second, the kinematics of the migrating continental fore-arc (western Washington) as it encounters a rigid buttress (Vancouver Island) are being examined by analysis of the velocity field from the PANGA array, and development of fault geometry and mechanical block models of the intraplate deformation of the Cascadia margin and Puget Lowlands.