Quantitative analysis of the Costa Rica margin 3D seismic volume to reveal subduction zone structure, tectonics, and the development of the seismogenic zone

俯冲带是发生大地震和海啸的地方，但由于地质和水文条件沿给定的边缘变化，区域人类风险各不相同。太平洋板块滑入哥斯达黎加下方的“巨型逆冲断层”内流体的存在(可能是润滑性的)将被记录下来，并与地震活动的模式有关。在巨型逆冲断裂之上，许多较小的断裂控制着沉积楔形体内的变形。这项研究将对这一差距的演变提供新的理解，并将获得更全面的危险范围的图景。下一代海洋科学家的培训将通过本科生参与数据分析进行，一名博士后学者将在整个研究过程中发挥重要作用。对哥斯达黎加边缘近海部分的结构分析将证明沉积楔体内部和底部的流体通道，该沉积楔体形成了覆盖巨型逆冲断层的构造板块的脚趾。将对R/V朗塞特以前收集的三维多道地震反射数据集进行高级分析。先前的研究确定了巨型逆冲的几何形状，而这项研究将量化断裂带内的物理性质。振幅与偏移量的关系结果应该能辨别出巨型逆冲断层的部分是否含流体。与地震活动模式的关系将解决流体在控制沿断层的历史滑动方面的可能作用。将对充斥着小断层的吸积楔进行详细的结构模拟，以显示随着时间的推移，覆盖板的变形是如何适应的。对遗留的海底地震折射剖面的重新分析将提供与边缘邻近部分的速度结构的比较，以便评估沿走向的可变性。这些发现将为解释过去和未来可能的科学海洋钻探结果提供关键背景。

Subduction zones are where major earthquakes and tsunami generation occur but the regional human risk varies since geologic and hydrologic conditions vary along a given margin. The presence of (possibly lubricating) fluid within the 'megathrust fault' where the Pacific plate slides down beneath Costa Rica will be documented and related to the pattern of seismicity. Above the megathrust fault, many smaller faults control deformation within the sedimentary wedge. This study will provide new understanding of this margin's evolution and a more complete picture of the range of hazards will be obtained. Training of next generation marine scientists will take place via involvement of undergraduate students in the data analysis and a postdoctoral scholar will play a significant role throughout the study. Analysis of the structure of an offshore portion of the Costa Rica margin will document fluid pathways within and at the base of the sedimentary wedge that forms the toe of the tectonic plate that overrides the megathrust fault. Advanced analysis of the 3-D multi-channel seismic reflection dataset previously collected by the R/V Langseth will be conducted. Prior study determined the geometry of the megathrust and this study will quantify physical properties within the fault zone. Amplitude versus offset results should discern whether portions of the megathrust fault are fluid bearing. The relation with seismicity patterns will address the possible role of fluids in controlling historical slip along the fault. Detailed structural modeling of the accretionary wedge, which is riddled with small faults, will be conducted to show how deformation of the overriding plate is accommodated over time. Re-analysis of a legacy ocean bottom seismic refraction profile will provide comparison to velocity structure in a neighboring part of the margin so that along-strike variability can be assessed. The findings will provide key context for interpretations of past and possible future scientific ocean drilling results.