An Open-Access, Controlled-Source Seismic Dataset Across the Cascadia Accretionary Wedge From Multi-Scale Regional OBS and Focused Large-N Nodal Arrays

来自多尺度区域 OBS 和聚焦大 N 节点阵列的跨卡斯卡迪亚增生楔的开放获取、受控源地震数据集

• 批准号: 1929545
• 负责人: Juan Pablo Canales
• 金额: $ 90.44万
• 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: 2019
• 资助国家: 美国
• 起止时间: 2019-08-01 至 2023-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1929545&HistoricalAwards=false
• 关键词: Open; Access; Controlled; Source; Seismic

Geologic hazards such as large megathrust earthquakes and tsunamis occur at convergent margins where tectonic forces push and drag one tectonic plate beneath another. One example of a convergent margin is the Cascadia Subduction Zone off western North America, where the slow ongoing descent of the Juan de Fuca plate beneath coastal northern California, Oregon, Washington and British Columbia has generated large earthquakes and associated tsunamis in the past. Knowledge of the structural and physical properties of the sediments that are being scraped off the Juan de Fuca plate and pushed onto the North American plate is of great importance because the presence of thick sediments increases the potential for great megathrust earthquakes. The scraped off sediments along the Cascadia margin contain significant amounts of naturally occurring methane gas and other fluids. The presence and variations of these fluids along the margin have a large impact on how the seabed responds and shakes during an earthquake. This project will deploy sensors (ocean bottom seismometers and nodes) on the seabed along a series of lines extending from near the coastline out to ~100 miles offshore Oregon, Washington and British Columbia to record signals from human-made acoustic pulses as well as from naturally occurring seismicity. The data recorded by these sensors will allow researchers to document variations in earthquake shaking properties of the sediments off the US west coast. Such information is critical for predicting shaking along the western US under hypothetical scenarios of future large earthquake rupture and assessing tsunami and submarine landslide hazards caused by earthquakes. This project will be conducted in partnership with the USGS. The project leverages an already funded seismic reflection survey of the Cascadia margin, increasing the scientific return by enabling a whole new suite of scientific data to be collected and broadening the base of potential users for these complementary open-access data sets.The goal of this project is to acquire an open-access, marine wide-angle seismic reflection/refraction dataset across the Cascadia accretionary wedge encompassing the full length of the margin. This survey will consist of the deployment and recovery of short-period multicomponent ocean bottom seismometers using standard free-fall and acoustic release techniques, and the deployment and recovery of large-N arrays of ocean bottom nodes leased from a commercial provider using a remotely operated vehicle. The sensors will record the controlled-source acoustic signals of a seismic reflection survey off the Cascadia margin planned for summer 2020. The data collected will be open-access and will be released to the community immediately after acquisition and checked for quality control. The data will be reduced to standard digital formats as well as provided as a raw continuous digital time series. The seismometer and nodal arrays will sample the seismic wavefields at different spatial scales, thus providing a data set that is optimal for obtaining seismic compressional- and shear-wave velocity models of the Cascadia accretionary wedge at three complementary scales: 1. A margin-scale model (~100-km lateral resolution) encompassing the full length of the subduction zone. 2. Regional, intermediate-resolution transects (~10-km lateral resolution) from the abyssal plain to the continental shelf. 3. Local, high-resolution models (hundreds-of-meters lateral resolution) across three transects representative of distinct accretionary wedge structural style and known structural heterogeneities. The project will provide much needed data to create accurate, multi-resolution models of the subsurface structure of the Cascadia accretionary prism, filling a critical knowledge gap for improving earthquake and tsunami hazard assessments for Cascadia. The data will enable researchers to develop models at complementary spatial scales using a variety of state-of-the-art methodologies, including multi-parameter 2-D elastic full waveform inversion, to address multiple scientific problems of high importance, such as: (a) Documenting variations in accretionary wedge site response, which is critical for predicting earthquake-triggered shaking along the western US and assessing tsunami/landslide hazards under hypothetical scenarios of future megathurst rupture, and to test proposed linkages between paleo great earthquakes and distribution of turbidites. (b) Determining accretionary sediment properties (Vp, Vs, density, porosity, and fluid pore pressure) indicative of fluid expulsion and/or retention, drainage networks, and their relation to structural style and seafloor fluid seepage.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.

地质灾害，如大型逆冲地震和海啸，发生在构造力把一个构造板块推到另一个构造板块下面的会聚边缘。汇聚边缘的一个例子是北美西部的卡斯卡迪亚俯冲带，在加利福尼亚北部、俄勒冈州、华盛顿州和不列颠哥伦比亚省沿海的胡安·德·富卡板块缓慢下降的过程中，过去曾引发过大地震和相关的海啸。了解从胡安·德·富卡板块刮下来并推到北美板块上的沉积物的结构和物理性质是非常重要的，因为厚沉积物的存在增加了发生特大逆冲地震的可能性。沿着卡斯卡迪亚边缘刮下来的沉积物含有大量自然产生的甲烷气体和其他流体。这些流体在边缘的存在和变化对海底在地震期间的反应和震动有很大的影响。该项目将在海底沿着一系列线路部署传感器（海底地震仪和节点），这些线路从俄勒冈州、华盛顿州和不列颠哥伦比亚省的海岸线附近延伸到离岸约100英里处，以记录来自人造声波脉冲和自然发生的地震活动的信号。这些传感器记录的数据将使研究人员能够记录美国西海岸附近沉积物的地震震动特性的变化。这些信息对于预测未来大地震破裂的假设情景下美国西部的震动以及评估地震引起的海啸和海底滑坡危害至关重要。该项目将与美国地质勘探局合作进行。该项目利用了已经获得资助的Cascadia边缘地震反射调查，通过收集一整套全新的科学数据，扩大了这些补充开放访问数据集的潜在用户基础，从而提高了科学回报。该项目的目标是获取一个开放的、海洋广角地震反射/折射数据集，覆盖整个边缘的Cascadia增生楔。此次调查将包括使用标准的自由落体和声波释放技术部署和恢复短周期多分量海底地震仪，以及使用远程操作车辆从商业供应商租用的大n海底节点阵列的部署和恢复。这些传感器将记录计划于2020年夏季在卡斯卡迪亚边缘进行地震反射调查的可控源声信号。收集到的数据将是开放获取的，并将在获取后立即发布给社区，并进行质量控制检查。这些数据将被简化为标准的数字格式，并作为原始的连续数字时间序列提供。地震仪和节点阵列将在不同的空间尺度上对地震波场进行采样，从而提供一个数据集，该数据集最适合在三个互补尺度上获得卡斯卡迪亚吸积楔的地震纵波和横波速度模型。一个边缘比例尺模型（~100公里横向分辨率），包括整个俯冲带的长度。2. 从深海平原到大陆架的区域中分辨率横断面（~10公里横向分辨率）。3. 局部高分辨率模型（数百米横向分辨率）跨越三个样带，代表了不同的增生楔形结构样式和已知的结构非均质性。该项目将为建立准确的、多分辨率的Cascadia增生棱镜地下结构模型提供急需的数据，填补了改善Cascadia地震和海啸危害评估的关键知识空白。这些数据将使研究人员能够使用各种最先进的方法（包括多参数二维弹性全波形反演）在互补的空间尺度上开发模型，以解决多个高度重要的科学问题，例如：(a)记录累积楔块场地反应的变化，这对于预测美国西部地震引发的震动和评估未来特大断层假设情景下的海啸/滑坡危害，以及检验提出的古大地震与浊积物分布之间的联系至关重要。(b)确定表明流体排出和/或滞留、排水网络的沉积性质（Vp、Vs、密度、孔隙度和流体孔隙压力），以及它们与构造样式和海底流体渗流的关系。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

CASIE21-OBS: An Open-Access, OBS Controlled-Source Seismic Data Set for Investigating the Structure and Properties of the Cascadia Accretionary Wedge and the Downgoing Explorer-Juan de Fuca-Gorda Plate System

CASIE21-OBS：开放获取、OBS 受控源地震数据集，用于研究卡斯卡迪亚增生楔和下行探索者胡安·德·富卡-戈尔达板块系统的结构和性质

• DOI: 10.1785/0220230010
• 发表时间: 2023
• 期刊: Seismological Research Letters
• 影响因子: 3.3
• 作者: Canales, Juan Pablo;Miller, Nathaniel C.;Baldwin, Wayne;Carbotte, Suzanne M.;Han, Shuoshuo;Boston, Brian;Jian, Hanchao;Collins, John;Lizarralde, Dan
• 通讯作者: Lizarralde, Dan