Shear Wave Velocity Structure Beneath Alaska from Rayleigh Wave Amplification and Phase Velocity
Abstract
Alaska is located along the Alaskan-Aleutian subduction zone, where the Pacific plate subducts beneath the North American plate. This subduction zone creates unique surface features such as the Aleutian volcanic chain, the Wrangell volcanic field, and the Denali volcanic gap. We use Rayleigh wave amplification and phase velocity measurements to better understand how the structure of the crust and upper mantle relate to the surface features. We consider teleseismic events with MW > 5.9, depth < 50 km, and epicentral distance between 20 and 160 degrees away that were recorded by the EarthScope Transportable Array stations. We use the Automated Surface Wave Measuring System (Jin and Gaherty, 2015) to measure amplitude and travel time from Rayleigh waves with periods 20 to 140 seconds. Phase-velocity maps are determined with the Helmholtz approach of Lin and Ritzwoller (2011). Local site amplification is determined with the amplitude-ratio approach of Eddy and Ekström (2014). We simultaneously invert the amplification and phase-velocity values to build a model of the Earth's shear wave velocity structure in the study region, taking advantage of the complementary sensitivities of the two data sets. The shear wave velocity structure can be used to understand the physical and chemical properties of the crust and mantle below Alaska.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.T41F0305D
- Keywords:
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- 1037 Magma genesis and partial melting;
- GEOCHEMISTRY;
- 8170 Subduction zone processes;
- TECTONOPHYSICS;
- 8178 Tectonics and magmatism;
- TECTONOPHYSICS;
- 8185 Volcanic arcs;
- TECTONOPHYSICS