Velocity Structure of the Saint Elias, Alaska, Region from Local Earthquake Tomography

A comprehensive seismic study of the Saint Elias region in Alaska reveals significant variations in crustal velocity, providing new insights into the tectonic processes shaping this UNESCO World Heritage Site. The research, utilizing data from over 8000 earthquakes and approximately 150,000 seismic arrivals recorded by a dense broadband network, identifies slower velocities along the northern edge of the Yakutat microplate, extending to depths of 30 km. This anomaly contrasts with offshore areas and regions north of the Chugach–St. Elias and Bagley faults, indicating tectonic deformation and off-scraping of Yakutat sediments. The study also images a northward-dipping Yakutat basement that extends towards the Wrangell volcanoes, while higher crustal velocities are observed between the Bagley fault and the Wrangell volcanic field. Additionally, a strong low-velocity anomaly corresponding to the Copper River sedimentary basin is traced down to 20 km depth.

Zabelina, I., Ruppert, N. A., & Freymueller, J. T. (2014). Velocity Structure of the Saint Elias, Alaska, Region from Local Earthquake Tomography. Bulletin of the Seismological Society of America, 104(5), 2597–2603. https://doi.org/10.1785/0120140072