Collaborative Research: Simultaneous Inversions of GPS Time Series for Kinematics and Transients in Cascadia

合作研究：卡斯卡迪亚运动学和瞬变的 GPS 时间序列同步反演

• 批准号: 0946634
• 负责人: Robert King
• 金额: $ 9.84万
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-04-01 至 2012-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0946634&HistoricalAwards=false
• 关键词: Collaborative; Research; Simultaneous; Inversions; GPS

In recent years continuously operating GPS sites have been established in many parts of the world, including Earthscope's Plate Boundary Observatory network in the western US. Prior to that, most GPS observations were made in survey-mode, where campaigns were used to occupy the marks on a yearly or multi-year basis. This project is to explore how to extract long-term plate kinematics and time-dependent deformation information from both continuous and survey-mode GPS data. The science target is to learn about the spatial and temporal relationship between slow slip and non-volcanic tremor throughout Cascadia. The continuous networks of PBO and PANGA are being used to test whether or not slow slip beneath Cascadia coincides spatially and temporally with non-volcanic tremor. Southern Cascadia has a very different pattern of slow-slip than northern Cascadia where slow-slip events are very regular and similar in size. Non-volcanic tremor suggests that there may be some, but different, patterns in southern Cascadia but tremor does not constrain the sizes of the slow slip events. Utilizing the time series directly in the analyses and applying new GPS processing techniques will enhance the signal-to-noise ratio of the vertical component which is critical in estimating the up-dip extent of slow slip on the Cascadia interface. One goal is to test whether or not non-volcanic tremor (NVT) coincides with slow slip. Since NVT is easier to observe than slow slip for small events, their coincidence will help delineate the portions of faults that slip slowly. The work will place important bounds on the up-dip limit of slow slip at Cascadia and hence whether or not slow slip extends into the locked portions of the megathrust. The research will further our understanding of slow-slip events and how they should be presented to the public. The simple question of whether they increase or decrease the earthquake hazard is not yet answered but is of obvious importance.

近年来，全球许多地方都建立了连续运行的GPS站点，包括美国西部的地球镜板块边界观测网。在此之前，大多数全球定位系统观测是在调查模式下进行的，在这种模式下，运动被用来每年或多年占据标记。本项目旨在探索如何从连续和测量模式的GPS数据中提取长期板块运动学和随时间变化的变形信息。科学目标是了解整个卡斯卡迪亚缓慢滑动和非火山地震之间的空间和时间关系。PBO和PANGA的连续网络被用来测试卡斯卡迪亚下方的缓慢滑动是否在空间和时间上与非火山震颤相一致。南部卡斯卡迪亚的慢滑模式与北方卡斯卡迪亚的慢滑模式非常不同，北部卡斯卡迪亚的慢滑事件非常有规律，大小相似。非火山震颤表明，在卡斯卡迪亚南部可能有一些，但不同的模式，但震颤并不限制缓慢滑动事件的大小。在分析中直接利用时间序列和应用新的GPS处理技术将提高垂直分量的信噪比，这对于估计卡斯卡迪亚界面上缓慢滑动的上倾程度至关重要。一个目标是测试非火山震颤（NVT）是否与缓慢滑动相一致。由于NVT比小事件的缓慢滑动更容易观察，它们的重合将有助于描绘缓慢滑动的断层部分。这项工作将对卡斯卡迪亚缓慢滑动的上倾极限以及缓慢滑动是否延伸到巨型逆冲断层的锁定部分产生重要影响。这项研究将进一步加深我们对慢滑事件的理解，以及如何向公众展示它们。它们是增加还是减少地震危险的简单问题还没有答案，但显然是重要的。