New Images of the Radially Anisotropic Uppermost Mantle Beneath the Continental Us
Description:
Tomographic models of radial anisotropy can help understand the relationship between stress and deformation in the upper mantle, and have been used in the past to study mantle convection and flow in the asthenosphere. Beneath the U.S, the current generation of models of radial anisotropy show strong disagreement with each other. Incorporating Love wave phase velocities in the construction of these models offers a path forward to reconcile them, but Love wave phase velocity measurements can suffer from systematic bias and scatter due to contamination by overtone interference.
In this study, we develop and successfully apply a simple method to identify and eliminate contaminated Love wave measurements. This approach reduces the detrimental impact of overtone interference through reducing a bias to higher phase velocity measurements and reducing scatter in measurements. We present the first earthquake-derived Love wave phase velocity maps for USArray, at periods with sensitivity in the crust and uppermost mantle. We show that radial anisotropy in parts of the crust and most of the lithospheric mantle is necessary to reconcile these maps with Rayleigh wave phase velocities. . We also show initial results from a new 3-D radially anisotropic model of the U.S..
Finally, our investigations highlight strong geographic and period-dependent variations in the likelihood of obtaining high-quality, uncontaminated Love wave measurements. High-quality measurements are more likely at European stations and less likely at stations in the Pacific, western US, and Australia, as a result of regional variations in the path-averaged group velocities.
Overall, this contribution presents a solution to a long-standing challenge in measuring Love wave phase velocities across seismic arrays, and it highlights new paths forward to validate hypotheses for the nature and evolution of the lithosphere of the continental U.S.
Session: Earth’s Structure From the Crust to the Core
Type: Oral
Date: 4/18/2023
Presentation Time: 09:00 AM (local time)
Presenting Author: Anant Hariharan
Student Presenter: Yes
Invited Presentation:
Authors
Anant Hariharan Presenting Author Corresponding Author anant_hariharan@brown.edu Brown University |
Colleen Dalton colleen_dalton@brown.edu Brown University |
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New Images of the Radially Anisotropic Uppermost Mantle Beneath the Continental Us
Category
Earth’s Structure From the Crust to the Core