Constraining the relationship between orogenesis and seismogenesis along the southern Cascadia forearc

美利坚合众国太平洋西北地区的造山运动显示出沿其长度（加州的北方至美国-加拿大边界）沿着的显著变化。特别地，与俄勒冈州和华盛顿州的相同位置相比，海岸线和活火山系统之间的区域在最北的加州（在40 - 42度纬度之间）的最宽区域中具有最高海拔。这可能是由于圣安德烈亚斯断层系统的北方部分和太平洋西北部的卡斯卡迪亚俯冲带之间复杂的相互作用，前者可以产生7级地震，后者被认为能够产生9级地震。此外，相对较新发现的现象（幕式震颤和缓慢滑动地震）在这一部分的边缘普遍存在，并可能有助于造山运动，因此地震的潜力。该项目的目的是通过分析最近获得的从地球上40英里的地下图像创建的数据集，更好地了解卡斯卡迪亚前弧这一部分的变形与造山运动和地震类型和成因的关系。了解北方加州这些不同的地质特征之间的相互关系，并将它们与进一步向北在俄勒冈州和华盛顿州观察到的情况进行比较，也可以深入了解这些地区的灾害和造山过程。该团队还将与北方加州的当地社区合作，交流该地区的基本地质和构造背景;开发一个维基百科页面，使公众可以访问实验，项目目标和主要结果;俯冲边缘的结构和流变特性直接影响地震的发生和板块的变形，但对几个方面仍然知之甚少。该研究小组将调查南部卡斯卡迪亚边缘（北方加州）的组成，结构和地震特征如何有助于广泛的隆起，地形演变，以及通过分析新收集的数据从60个节点地震站与预先存在的和目前运行的地震站的高速率的幕式震颤和滑动。为了限制前弧的特征，该团队将应用强大的和新颖的地震方法，包括：1）接收器函数成像，2）体波和表面波环境噪声干涉测量，3）接收器函数和表面波色散测量的联合反演，以获得该地区新的3D剪切波速度模型，以及4）震源机制分析。深入了解这些特征如何与南部卡斯卡迪亚的俯冲表达，然后将被用来更好地了解是什么控制的变化，在其他地方的俯冲表现沿着卡斯卡迪亚边缘。此外，这些弧前地壳结构的高分辨率图像将允许更好地了解可能的物理，成分和流变控制的过程中的幕式震颤和slive.This奖项反映了NSF的法定使命，并已被认为是值得的支持，通过评估使用基金会的智力价值和更广泛的影响审查标准。

Mountain building in the Pacific Northwest region of the United States of America shows significant variation along its length (northern California to the US-Canada border). In particular, the region between the coastline and the active volcanic system has the highest elevations over the broadest region in northernmost California (between 40 – 42 degrees latitude) compared to the same locations in Oregon and Washington State. This likely arises from the complex interactions between the northern portion of the San Andreas Fault System that can generate magnitude 7 earthquakes and the Cascadia Subduction Zone in the Pacific Northwest, thought to be able to generate magnitude 9 earthquakes. In addition, relatively newly-discovered phenomena (episodic tremor and slow slipping earthquakes) are prevalent in this portion of the margin, and may contribute to mountain building, and therefore earthquake potential. The purpose of this project is to better understand how deformation in this portion of the Cascadia forearc relates to mountain building and earthquake style and genesis by analyzing a recently acquired dataset created from subsurface images of the upper 40 miles of Earth. Understanding the interrelationships between these different geological characteristics in northern California and comparing them to what is observed further to the north in Oregon and Washington State, may also provide insights into the hazard and mountain building processes in those regions. The team will also engage with the local community in northern California to communicate the basic geologic and tectonic context of the region; develop a Wikipedia page to make the experiment, project goals, and major results accessible to the general public; and contribute to the training of graduate and undergraduate students.The structural and rheological properties of a subduction margin directly influence seismogenesis and overriding plate deformation, but several aspects remain poorly understood. The research team will investigate how the composition, structure, and seismic character of the southern Cascadia margin (northern California) contributes to broad uplift, topographic evolution, and high rates of episodic tremor-and-slip by analyzing newly-collected data from 60 nodal seismic stations with pre-existing and currently operating seismic stations. To constrain the characteristics of the forearc, the team will apply both robust and novel seismic methodologies, including: 1) teleseismic receiver function imaging, 2) body and surface wave ambient noise interferometry, 3) a joint inversion of receiver functions and surface wave dispersion measurements to obtain a new 3D shear-wave velocity model of the region, and 4) focal mechanism analysis. Insight into how these characteristics relate to the expression of subduction in southern Cascadia will then be used to better understand what controls variability in the manifestation of subduction elsewhere along the Cascadia margin. In addition, these high-resolution images of forearc crustal structure will allow for the better understanding of the possible physical, compositional, and rheological controls on the processes of episodic tremor-and-slip.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.