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

基本信息

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

项目摘要

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.

对最近获取的多道地震（MCS）数据的分析将解决一系列与卡斯卡迪亚俯冲带西澳中部沿岩石圈结构和边缘演化相关的主题，以及这些主题与当前地震活动模式的关系。预计对约 1100 公里 MCS 数据网格进行高级处理，以确定板块边界的深度和特征，并对当前俯冲的沉积物量进行评估。增生楔内地层的变形将被绘制出来，以追踪板块相互作用的长期演化。地壳水合作用的估计将通过假设的地震速度-孔隙度关系以及沿界面的反射率来获得。将绘制显示该地区甲烷水合物分布的地图。研究结果将提供一个框架，在该框架内进行其他卡斯卡迪亚地球科学研究，包括地震过程和构造演化，并且可能对灾害评估产生影响。虽然该俯冲带目前的地震活动少于世界其他区域，但在数百年的时间尺度上重复发生大型逆冲事件的陆上证据是清晰的，因此了解应力积累（地层变形）的历史和程度非常重要沿着断层的流体可能会带来一段“润滑”、缓慢的应力释放。