[Eoas-seminar] Colloquium Thursday Jan 18 3:30

eoas-seminar at lists.fsu.edu eoas-seminar at lists.fsu.edu
Wed Jan 17 15:27:06 EST 2018

Announcing a colloquium presentation entitled:
Mantle structure and dynamics under the continuous United States inferred from tomographic shear velocity imaging.

by: Dr. R. Porrit, University of Texas at Austin
Thursday January 18th at 3:30pm in Baum Room (353 LOV)

The mantle under the continuous United States is a dynamic region of interacting downwellings and upwellings. First order structural imaging has shown a broadly warm western US and cool eastern US. This correlates well with Basin and Range extension in the west and a passive cratonic plate in the east. However, this view does not account for other major features, such as the Cascades Volcanic Arc, the Yellowstone Hotspot, and a lower mantle high velocity feature near the core-mantle boundary under the eastern US imaged in global tomographic studies. The USArray seismic experiment provides unprecedented seismic data coverage of the continuous US and has therefore spurred significant advances in tomographic and geodynamic modeling. Here, we present recent shear velocity models derived from seismic travel times to investigate the structure of the continuous US. The models use travel times of both surface waves and body waves to constrain structure in the crust and mantle in terms of radially anisotropic shear velocity. High resolution regional models resolve several significant high velocity features embedded within the western US, which are generally interpreted as fragments of the subducting Farallon slab. Recent geodynamic modeling suggests these downwellings may provide the driving force for return flow upwards resulting in much of the western US volcanism. However, these geodynamic models are based on regional imaging studies which may suffer from edge effects and lack vital information such as anisotropy and absolute shear velocities. Therefore, our new model is global in scope, but with increased resolution under the USArray footprint. With this model, we can begin to quantitatively test geodynamic models involving mantle flow and resulting dynamic topography with an internally consistent mantle structural model.
Dr. Vincent J.M. Salters
National High Magnetic Field Laboratory and Department of Earth, Ocean and Atmospheric Sciences
Florida State University
Tallahassee, Florida
Phone: 850-644-1934, Skype: vsalters

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