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WITHDRAWN The Comparison of Depth-Dependent Seismic Azimuthal Anisotropy Beneath Alaska-Aleutian and Cascadia Subduction Systems

Description: 

WITHDRAWN In North America, the oceanic Pacific plate beneath Alaska is old and cold, in contrast with the young, warm Juan de Fuca plate subducting beneath Cascadia. The two subduction systems differ from each other due to various tectonic characteristics, such as the age and morphology of the subducted slab, convergence direction, the surrounding mantle dynamics, and so forth. Due to these factors, different subduction systems can produce distinctive structural heterogeneities and leave diverse observable seismic anisotropic signatures. The comparison of seismic anisotropic structures beneath these two subduction systems can help to illuminate differences in dynamic processes that occur under different conditions.

Benefiting from the improvements in seismic instrumentation both onshore and offshore in Alaska (e.g., Alaska Amphibious Community Seismic Experiment (AACSE) and USArray) and Cascadia (e.g., Cascadia Initiative (CI) and USArray), we have constructed high-resolution surface wave dispersion databases with associated uncertainties in these two regions. Based on Rayleigh wave isotropic phase speed and azimuthal anisotropy in these two databases, we construct models of depth-dependent azimuthal anisotropy for both the crust and the uppermost. The anisotropic models in these two subduction zones reflect similarities and differences in both forearc and backarc regions. The characteristics of azimuthal anisotropy suggest different mantle flow patterns beneath the Alaska-Aleutian and the Cascadia subduction systems.

Session: Subduction Zone Structure From Trench to Arc

Type: Oral

Date: 4/19/2023

Presentation Time: 11:00 AM (local time)

Presenting Author: Chuanming Liu

Student Presenter: Yes

Invited Presentation: 

Authors