Full-wave anisotropy tomography for the upper mantle of Alaska

Located on the western edge of the North American plate, Alaska is formed over time through the accretion of various terranes. The subductions of the Pacific and Yakutat plates have significantly influenced the intense tectonic activity in this region, making Alaska an attractive area for geophysical study.

Seismic anisotropy provides critical insights into the deformation mechanisms beneath this tectonically active region and serves as a key factor for regional seismotectonic analysis. In this study, we invert the SKS wave splitting intensities for the 3D variations of shear-wave anisotropy. Using broadband seismograms from 344 regional seismic stations with unprecedented spatial density, we measure the splitting intensities of SKS waves from teleseismic events with magnitudes greater than 5.5 recorded between 2000 and 2023. A total of 9,604 SKS splitting intensity measurements are obtained and incorporated into a multi-scale inversion framework, utilizing sensitivity kernels calculated by normal-mode summation.

The resulting 3D anisotropy model reveals detailed deformation patterns which is interpreted in the context of Alaska’s complex seismotectonic environment. This work enhances our understanding of mantle flow and tectonic processes in a region of significant geophysical and geological interest.