Structure and Hydration of the Explorer-Juan de Fuca-Gorda Plate System at the Onset of Subduction Beneath Cascadia

卡斯卡迪亚以下俯冲开始时探索者-胡安·德·富卡-戈达板块系统的结构和水合作用

• 批准号: 2237773
• 负责人: Juan Pablo Canales
• 金额: $ 48万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-01-01 至 2024-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2237773&HistoricalAwards=false
• 关键词: Structure; Hydration; Explorer; Juan; de

Earthquakes, tsunamis, and explosive volcanism are geohazards associated with subduction zones. Understanding the variability along the subduction zone is important for what controls geohazards in this populated region of North America. This project will analyze marine seismic profiles along the Cascadia margin from offshore Vancouver Island to southern Oregon. Measurements and analyses will constrain variability in subducting sediment thickness, amount of water in the downgoing plate, and topography of the sediment-basement interface. This project will contribute to the education of two graduate students by providing them support, data and training in geophysical imaging.In 2021, a suite of modern and extensive controlled-source seismic datasets was collected along profiles spanning most of the length of the Cascadia margin. The datasets along ten of the profiles consist of co-located ultralong-streamer multichannel seismic reflection and wide-angle seismic reflection/refraction data recorded in ocean bottom seismometers (OBSs). The project will use these datasets to model the seismic properties and structure of the sediments, crust and mantle of the incoming and down-going plates as well as those of the accretionary prism. Fracturing and alteration of crustal and mantle rocks give rise to detectable changes in seismic velocities, and seismic methods provide an important remote sensing tool for assessing plate hydration. The researchers will produce models of the P-wave and S-wave seismic velocity structure along each OBS transect using state-of-the-art wide-angle seismic data processing and imaging methods, including downward-continuation of ultra-long streamer data, super-virtual refraction interferometry, and joint travel-time refraction/reflection tomography of streamer and OBS data. The seismic velocity models will be used together with effective medium theory to constrain crust and mantle porosity, and the amount and distribution of fluid and chemically-bound water of the incoming and down-going plate. The findings from this project will be of great interest to researchers investigating Cascadia subduction zone processes, from the deformation front to sub-arc depths. The project results will also be a key component for updating and improving the U.S. Geological Survey’s margin-scale 3-D seismic velocity model for Cascadia.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.

地震、海啸和火山爆发是与俯冲带相关的地质灾害，了解俯冲带的变化对于控制北美这一人口稠密地区的地质灾害非常重要。该项目将分析温哥华岛近海卡斯卡迪亚边缘的海洋地震剖面。测量和分析将限制俯冲沉积物厚度、下降板块中的水量以及沉积物-基底界面的地形的变化，该项目将有助于两个人的教育。 2021 年，沿着跨越卡斯卡迪亚边缘大部分长度的剖面收集了一套现代且广泛的受控源地震数据集，这些数据集沿着 10 个组成剖面。该项目将使用这些数据集来模拟地震特性。传入和下降板块的沉积物、地壳和地幔以及增生棱柱的沉积物和结构，地壳和地幔岩石的破裂和蚀变引起了地震速度的可检测变化，地震方法提供了重要的遥测方法。研究人员将使用最先进的广角地震来制作沿每个 OBS 横断面的 P 波和 S 波地震速度结构模型。数据处理和成像方法，包括超长拖缆数据的向下延拓、超虚拟折射干涉测量、拖缆和OBS数据的联合走时折射/反射层析成像，地震速度模型将与有效介质理论结合使用。限制地壳和地幔的孔隙度，以及传入和下降板块的流体和化学结合水的数量和分布，该项目的发现将对研究人员产生极大的兴趣。卡斯卡迪亚俯冲带过程，从变形前缘到弧下深度。该项目的结果也将成为更新和改进美国地质调查局卡斯卡迪亚边缘尺度 3D 地震速度模型的关键组成部分。该奖项反映了 NSF 的法定使命。通过使用基金会的智力优点和更广泛的影响审查标准进行评估，并被认为值得支持。