Collaborative Research: A new subsurface framework for the Cascadia subduction zone derived from integrated analyses of the CASIE21 long-offset multi-channel seismic experiment

合作研究：根据 CASIE21 长偏移距多道地震实验的综合分析得出卡斯卡迪亚俯冲带的新地下框架

• 批准号: 2217466
• 负责人: Shuoshuo Han
• 金额: $ 35.43万
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-01 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2217466&HistoricalAwards=false
• 关键词: Collaborative; Research; new; subsurface; framework

The Cascadia Subduction Zone in the Pacific Northwest is a region of great national interest and growing public awareness because of its high earthquake and tsunami hazard. The Cascadia margin has low levels of recorded seismicity, which reduces what is known of the properties of the earthquake zone. This project aims to identify variations in the structure and properties of the Cascadia margin to better understand the earthquake and tsunami risk to the Pacific Northwest. This project will work with other groups to build a new 3-dimensional picture for the margin. The project will support for four graduate students, two postdoctoral researchers, and three early-career scientists.From June 1 to July 11, 2021, a regional-scale multi-channel seismic study of the Cascadia Subduction Zone was collected using the state-of-the-art long-offset capabilities of the R/V Marcus G. Langseth as part of the CAscadia Seismic Imaging Experiment 2021 (CASIE21). During the expedition, 5,347 km of high quality 12-15 km streamer data were acquired in a 50-75 km spaced grid of seismic lines spanning the margin from the northern Gorda plate at 42°N to the end of subduction offshore Vancouver Island and from ~50 km seaward of the deformation front to near the coastline. This new survey represents the first regional-scale study conducted at Cascadia, spanning most of the subduction zone and filling important gaps in data coverage. This project utilizes the CASIE21 dataset in order to study nearly the whole Cascadia margin and will yield unique insights into three core questions: (1) What is the geometry of the plate interface along the margin, where is significant sediment subduction occurring, and how do plate interface properties including reflectivity and roughness vary along the margin and down dip? How do plate interface properties relate to incoming plate and upper plate structure and megathrust rupture segmentation? (2) How do the structural style and evolution of the upper plate vary along strike and how are they related to megathrust strength, backstops, and fluid migration? (3) How does the lithostratigraphic architecture of the sediment section, and structure, deformation and hydration potential of the shallow-most oceanic crust of the incoming plate associated with bend faulting, distribution of seamounts and propagator shear zones vary along the margin and how do these properties contribute to wedge evolution and megathrust rupture segmentation? This study will result in construction of a new regional-scale structural interpretation of the offshore Cascadia region from seismic images as a primary product along with select studies making use of reflectivity, velocity models, and strain analysis.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.

太平洋西北部的卡斯卡迪亚俯冲带是一个具有重大国家利益的地区，由于其高地震和海啸危险性，公众意识日益增强。卡斯卡迪亚边缘记录到的地震活动水平较低，这降低了人们对地震带性质的了解。该项目旨在确定卡斯卡迪亚边缘的结构和性质的变化，以更好地了解太平洋西北部的地震和海啸风险。这个项目将与其他小组合作，建立一个新的三维图片的利润。该项目将支持四名研究生，两名博士后研究人员和三名早期职业科学家。2021年6月1日至7月11日，使用R/V Marcus G. Langseth是CAscadia地震成像实验2021（CASIE 21）的一部分。在考察期间，从北纬42度的北方戈尔达板块边缘到温哥华岛近海俯冲结束，从变形前缘向海约50公里到海岸线附近，在50-75公里的地震测线间隔网格中采集了5 347公里的高质量12-15公里拖缆数据。这项新的调查是在卡斯卡迪亚进行的第一次区域规模的研究，涵盖了大部分俯冲带，填补了数据覆盖方面的重要空白。该项目利用CASIE 21数据集，以研究几乎整个卡斯卡迪亚边缘，并将产生独特的见解三个核心问题：（1）什么是板块界面的几何形状沿着边缘，在哪里发生重大的沉积俯冲，以及如何板块界面属性，包括反射率和粗糙度变化沿着边缘和下倾？板块界面性质如何与进入板块和上部板块结构以及巨型逆冲断层破裂分段相关联？(2)上板块的构造样式和演化如何沿沿着走向变化？它们与巨型逆冲断层强度、逆止层和流体运移有何关系？(3)与弯曲断层、海山和传播剪切带的分布有关的沉积剖面的岩石地层结构、进入板块的最浅洋壳的结构、变形和水化潜力如何沿边缘沿着变化，以及这些特性如何有助于楔状体演化和巨型逆冲断层破裂分段？这项研究将导致建设一个新的区域规模的结构解释的海上卡斯卡迪亚地区的地震图像作为一个主要产品沿着与选择的研究利用反射率，速度模型，应变分析。这个奖项反映了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知识价值和更广泛的影响审查标准。