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

这项提议寻求资金，在华盛顿西部经度约123oW的南北剖面上部署7个临时宽带地震仪台站，以记录远震体波形。我们打算对记录的P波进行接收函数分析，以描绘俯冲板块Juan de Fuca板块大洋莫霍面的Ps转换的幅度和时间的变化，这表明俯冲板块沿其走向的几何形状的变化。具体地说，我们将试图证实和完善最近提出的一个工作假说，该假说认为胡安德·富卡板块可能在普吉特湾附近的一个宽阔的拱形中变形。这一模型解释了该区域下方地震活动的某些方面，以及其他一些地质和地球物理观测。我们在北纬约47oN的东西向剖面上记录了远震P波，这表明胡安德富卡板块的大洋莫霍面在远震接收功能上具有特征特征。这些早期部署的结果与我们的ARCH模型一致。这一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灾害潜力产生重要影响。这项研究是密苏里大学哥伦比亚分校(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).