2017) to model various types of ruptures in Cascadia.īelow are 2D seismic wavefield snapshots Mexico from Furamura & Kennett (1998).
This waveguide feature amplifies ground motions at distances over 180 km from the trench and increases duration of shaking. I propose to model various locations and sizes of subduction zone earthquakes in Cascadia in order to understand regional controls on wave propagation, and the possible existence and effects of a subduction zone waveguide. So far, most studies modeling the wave guide effect have been 2D, but I will use a well-supported wave propagation software, SPECFEM3D, in combination with a Cascadia velocity model (Stephenson et al. This leads to S-wave energy being channeled downdip in the subducting oceanic crust until it reaches the continental crust/mantle boundary, and much of the energy is reflected back up to the surface. The wedge-shaped subduction zone geometry causes strong reflections of S waves off the crust/mantle boundary, and as well as superpositions of reflected S waves trapped in both the oceanic and continental crust, due to lower velocity in the crust. Research has shown that subducting oceanic slabs can act as a guide for seismic waves (Furamura & Kennett, 1998). Modeling megathrust subduction earthquakes in Cascadia will lead to a better understanding of how waves propagate through subduction zones and improve the seismic hazard estimates in the region. The CSZ poses a significant risk to people and infrastructure in the Pacific Northwest. The Cascadia subduction zone (CSZ) has produced devastating earthquakes of magnitude 9 and larger, with and an estimated recurrence interval of 400-600 years, the most recent in 1700.
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