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Seismic Structure of Northern Alaska From Ambient Noise Adjoint Tomography

Northern Alaska is a remote, arctic region roughly 1000 km from the nearest plate boundary at the Alaska-Aleutian subduction zone. Physiographically, the region is dominated by the east-west trending Brooks Range and the adjacent Colville Basin and North Slope region. Seismically, northern Alaska is characterized by diffuse bands of seismicity, distributed crustal deformation, and moderate-sized earthquakes (M<6). In this work, we take advantage of years of high-quality seismic data from the EarthScope Transportable Array to undertake a seismic imaging study of northern Alaska. Our goal is to generate a 3D, high-resolution velocity model of structure below the region, in order to improve our understanding of the regional tectonics. To accomplish this, we use adjoint tomography, a seismic imaging method which seeks to minimize differences between seismic data and synthetically-generated waveforms from numerical simulations of wave propagation. We use the empirical Green's function (EGF) dataset of C. Liu et al. (2022), which is derived from ambient seismic noise and provides excellent data coverage of the region. Preliminary results demonstrate that our inversion is sensitive to crust and upper mantle structure, and it is able to resolve lateral velocity variations which show similarities to known geologic and tectonic features. Current efforts aim to invert the EGF dataset for a target period band of 8–50s. We present ongoing work from this project, including an updated, anisotropic velocity model, and key tectonic interpretations.

Session: Earth’s Structure from the Crust to the Core - I

Type: Oral

Room: Tikahtnu Ballroom E/F

Date: 5/1/2024

Presentation Time: 08:45 AM (local time)

Presenting Author: Bryant Chow

Student Presenter: No

Additional Authors