Collaborative Research: Imaging plate boundary processes within the Cascadia subduction zone offshore central Washington with open-access marine seismic data

合作研究：利用开放获取的海洋地震数据对华盛顿中部近海卡斯卡迪亚俯冲带内的板块边界过程进行成像

• 批准号: 1335066
• 负责人: W Steven Holbrook
• 金额: $ 13.4万
• 依托单位: University of Wyoming
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-08-15 至 2015-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1335066&HistoricalAwards=false
• 关键词: Collaborative; Research; Imaging; plate; boundary

Analysis of recently acquired multi-channel seismic (MCS) data will address a series of topics that relate to the structure of the lithosphere and margin evolution along the central WA portion of Cascadia subduction zone and how these relate to current seismicity patterns. Advanced processing of the ~1100 km grid of MCS data is expected to identify the depth and character of the plate boundary and the amount of sediment currently being subducted will be assessed. Deformation of strata within the accretionary wedge will be mapped to track longer-term evolution of the plate interactions. Estimates of crustal hydration will be obtained from assumed seismic velocity - porosity relationships and, along interfaces, reflectivity. Maps showing the distribution of methane hydrates in the region will be produced.Results will provide a framework within which other Cascadia geoscience studies are conducted, both for seismic processes and tectonic evolution, and are likely to have implications for hazard assessment. While this subduction zone currently has less earthquake activity than other zones around the world, onshore evidence of repeated megathrust events is clear over times scales of hundreds of years, so it is important to understand the history of stress buildup (strata deformation) and the extent to which fluids along faults might enable periods of 'lubricated', slow stress release.

对最近获得的多道地震(MCS)数据的分析将涉及一系列与卡斯卡迪亚俯冲带中部Wa部分的岩石圈结构和边缘演化有关的主题，以及这些主题与当前地震活动模式的关系。对约1100公里的MCS数据进行高级处理，预计将确定板块边界的深度和特征，并将评估目前被俯冲的沉淀量。沉积楔形体内的地层变形将被绘制成地图，以跟踪板块相互作用的长期演化。地壳水合作用的估计将从假定的地震速度-孔隙度关系和沿界面的反射率获得。这些结果将为其他卡斯卡迪亚地学研究提供一个框架，包括地震过程和构造演化，并可能对危险评估产生影响。虽然这个俯冲带目前的地震活动比世界上其他地区要少，但在数百年的时间尺度上，陆上有明显的证据表明反复发生的巨型逆冲事件，因此重要的是要了解应力积累的历史(地层变形)，以及断层上的流体可能在多大程度上使“润滑”的、缓慢的应力释放时期发生。