COLLABORATIVE RESEARCH: Finite Element Modeling of a Subducted Topographic High: Determining Regional Stress Changes Due to Subducting Features

“合作研究：俯冲地形高压的有限元模拟：确定俯冲特征引起的区域应力变化”EAR 0440243和0440229由于全球大部分地震活动发生在俯冲带，因此了解俯冲环境中的应力条件非常重要。这些地区地震细节的变化很可能是由于俯冲带之间应力条件的变化。影响俯冲带应力条件的关键因素包括地幔流动和板块界面上的上、俯冲板块之间的相互作用。板块界面的粗糙度可能会根据进入板块的各种特征而变化，例如厚沉积物包、地垒和地堑结构、海山、山脊和断裂带的存在。这些俯冲板块构造不仅影响着俯冲带内的应力状态，而且可能控制着俯冲带大地震的大小和破裂行为，如哥斯达黎加和南开俯冲带的大地震。本研究的重点是研究这两个俯冲带的应力状态，目的是研究哥斯达黎加和南开地区的应力、俯冲特征和地震活动模式之间的关系，以及这些地区大地震的应力触发，并确定地形特征可能作为高地震滑动带或地震破裂屏障的条件。俯冲带环境的二维和三维建模将为探索粘弹性松弛和触发、海沟界面的摩擦特性以及俯冲海洋岩石圈的水深变化对地震模式的影响提供机会。这项工作的结果将应用于哥斯达黎加和南开的地震灾害知识，并可能推广到其他俯冲带。

Proposal "Collaborative Research: Finite Element Modeling Of A Subducted Topographic High: Determining Regional Stress Changes Due To Subducing Features" EAR 0440243 and 0440229 With the majority of global seismicity occurring in subduction zones, it is very important to understand the stress conditions in the subduction environment. Variations in the details of earthquakes in these regions are likely due to variations in stress conditions between subduction zones. Key factors that can impact the stress conditions in subduction zones include mantle flow and the interaction between the overriding and subducting plates at the plate interface. The plate interface may vary in roughness depending on a variety of features on the incoming plate, such as presence of thick sediment packets, horst and graben structures, seamounts, ridges, and fracture zones. These subducting plate structures not only influence the stress state within the subduction zone, but may also control the size and rupture behavior of large subduction zone earthquakes, as suggested for large earthquakes in Costa Rica and Nankai subduction zones. This proposal focuses on examining the stress state in these two subduction zones, with goals to examine the relationship between stresses, subducted features, and seismicity patterns seen in Costa Rica and Nankai, stress triggering of large earthquakes in these regions, and determining conditions for which topographic features may act as zones of high earthquake slip or a barrier to earthquake rupture. Two and 3D modeling of the subduction zone environment will provide opportunities to explore the effects of viscoelastic relaxation and triggering, frictional properties at the trench interface, and the bathymetric variability of the subducted oceanic lithosphere on earthquake patterns. Results from this effort will be applied to knowledge of earthquake hazards in Costa Rica and Nankai, and may be extended to other subduction zones as well.