Seismic Attenuation and Active Tectonics in Alaska

Abstract

Using deep teleseismic earthquakes recorded by the EarthScope Transportable Array and other temporary broadband deployments, we map the attenuation below Alaska. We measure 209 events that passed our quality control test using a time-domain approach to measure P wave attenuation. Our results show a good correlation with attenuation being dominated by sub-crustal structure and with expectations from the velocity-defined lithospheric domains. High-attenuation regions generally exhibit quaternary volcanic fields and arc and back-arc regions, which surprisingly show more attenuation than previous studies, highlighting the need for a better understanding of the effect of melt and volatile contents in mantle attenuation. Low-attenuation regions include an undeformed, seismically inactive region north of the Brooks Mountains. In addition, the remaining slab of the subduction zone from the interior of the continent also shows low attenuation. Comparisons made with additional features such as intra-continental deformation, magmatism, and seismicity contribute to our study.