[Eoas-seminar] Geophysics Job Talk Today @ 3:30 PM

[eoas-seminar at lists.fsu.edu]

Neala Creasy is candidate for the faculty search in "Geophysics”.

Zoom link for the talk: https://fsu.zoom.us/j/93286142639

Date and Time: March 1st 3:30 PM

Title: Deep Earth Seismology: Revealing the Birth of Plumes and the Death of Plates
Abstract:  Plate tectonics represents the surface expression of Earth’s convecting mantle, resulting from the continued cooling of the planet. Solid-state mantle convection drives subducting plates/slabs into the deep mantle, while driving plumes up to the surface as hotspot volcanism. Earthquake seismology has the power to image the interior of the planet to better understand these processes. While general seismic imaging (such as tomography or waveform modelling) can reveal the locations, properties, and dimensions of deep mantle objects (plumes, slabs, etc.), it cannot reveal the context of these features in relation to mantle flow. Therefore, the main way to characterize mantle flow is with seismic anisotropy (how seismic wave speeds change with direction). In this seminar, I illustrate the links that I have made between seismic observations, mineral physics experiments, and dynamics with an emphasis on the lowermost mantle (the D” region: 200-300 km thick region directly above the core mantle boundary). Based on recent modeling of anisotropy, we have been able to better constrain likely mechanisms for D”-anisotropy and possible directions of flow. However, these models are based on ray theory, an infinite frequency approximation to the wave equation. In my current research, I am exploring the limits of ray theory as applied to seismic anisotropy and imaging in general. I use 3D numerical modeling of the wave equation to explore finite frequency effects on seismic observations, such as anisotropy. In the future, I would like to better understand features in the deep mantle and core by the following: (1) expanding the number of observations of seismic heterogeneities and anisotropy in the deep Earth; (2) using full-waveform modeling to better constrain the mechanism of anisotropy in the D” layer; (3) better image and model the Earth’s outer core; and (4) work towards global full waveform inversion of shear wave splitting.

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