Collaborative Research: Delineation of the Slab Geometry of the Cascadia Subduction Zone Using Broadband Teleseismic Waveform Analysis

该提案寻求资金，在华盛顿西部经度约123°的南北剖面上部署7个临时宽带地震仪站，以记录远震体波形。我们打算对记录的纵波进行接收函数分析，以描绘来自俯冲的胡安·德富卡板块的大洋莫霍面p波转换的振幅和时间变化，这些变化表明俯冲板块沿其走向的几何形状变化。具体来说，我们将试图证实和完善最近提出的一个工作假设，即胡安·德富卡板块可能在普吉特海湾附近的一个宽阔的拱门中变形。这个模型解释了该地区地下地震活动的某些方面，以及许多其他地质和地球物理观测结果。在东西向剖面上记录的远震p波表明，Juan de Fuca板块的大洋莫霍在远震接收函数中具有特征特征。这些早期部署的结果与我们的arch模型一致。该模型的进一步完善将对卡斯卡迪亚俯冲带的构造演化和地震危险性具有重要意义。这项研究是密苏里-哥伦比亚大学（T.J. Owens）和华盛顿大学（R.S. Crosson）的合作项目。

This proposal seeks funding to deploy 7 temporary broadband seismograph stations in a north-south profile at a longitude of about 123oW in western Washington for the purpose of recording teleseismic body waveforms. We intend to undertake a receiver function analysis of the recorded P-waves in order to delineate variations in the amplitude and timing of Ps conversions from the oceanic Moho of the subducted Juan de Fuca plate that are indicative of variations in the geometry of the subducted slab along its strike. Specifically, we will attempt to confirm and refine a working hypothesis recently proposed that suggests that the Juan de Fuca plate may be deformed in a broad arch centered in the vicinity of Puget Sound. This model explains certain aspects of the seismicity beneath this region as well as a number of other geological and geophysical observations. We have recorded teleseismic P-waveforms along an east-west profile at about 47oN latitude that demonstrates that the oceanic Moho of the Juan de Fuca plate has a characteristic signature in teleseismic receiver functions. Results from these earlier deployments are consistent with our arch model. Further refinements in this model will have important implications in terms of the tectonic evolution and earthquake hazards potential of the Cascadia Subduction Zone. This research represents a collaborative project between the University of Missouri-Columbia (T.J. Owens) and the University of Washington (R.S. Crosson).