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.
