COLLABORATIVE RESEARCH: Forearc Deformation at Subduction Zone Cusp and Plate Coupling Variations in Cascadia

9814926McCaffrey胡安德·富卡板块的会聚和太平洋板块相对于北美的西北运动导致北美边缘向其内部数百公里处的活跃形变。这种形变有可能产生巨大的破坏性地震，并可以通过全球定位系统(GPS)在差动模式下非常准确地进行测量。调查人员将利用美国地质调查局在1991至1995年间收集的现有GPS数据，以及国家大地测量局、当地测量师和PI最近进行的测量，以检查这种变形的具体方面及其地质原因。在这项研究中，PI将集中在俄勒冈州和华盛顿州沿海地区的北向输送速率以及这种输送在沿海山脉生长中所起的作用，沿海应变率的变化可能与分隔胡安德富卡板块和北美的倾斜逆冲断层的分段有关，以及北移沿海地区和北美之间的边界位置。所有这些特征在全球其他几个收敛边缘都观察到了，这项针对美国太平洋西北地区的重点研究将帮助我们了解它们的根本原因。

9814926McCaffrey The convergence of the Juan de Fuca plate and the northwestward motion of the Pacific plate relative to North America result in active deformation of the North American margin several hundred kilometers into its interior. This deformation has the potential of producing large, damaging earthquakes and can be measured very accurately with the Global Positioning System (GPS) operating in the differential mode. The investigators will utilize pre-existing GPS data gathered by the US Geological Survey between 1991 and 1995 along with more recent measurements made by the National Geodetic Survey, local surveyors, and by the PIs to examine specific aspects of this deformation and their geological causes. In this study the PIs will focus on the rate of northward transport of the coastal regions of Oregon and Washington and the role this transport plays in the growth of coastal mountains, the variations in strain rates along the coast possibly related to segmentation of the dipping thrust fault separating the Juan de Fuca plate from North America, and the location of the boundary between the northward moving coastal region and North America. All of these features are observed in several other convergent margins globally and this focused study in the US Pacific Northwest will help us understand their underlying causes.