Seismicity studies of the Wadati -Benioff zone, South-Central Alaska

The project involves seismicity studies of the Wadati-Benioff zone, south-central Alaska. The Wadati-Benioff zone is a zone of deep earthquakes found throughout the world in subduction zones. The subduction zone is an area where an oceanic lithospheric plate is converging and diving under an overriding continental lithospheric plate and many earthquakes are associated with these zones. The motivation for this study is threefold: to identify seismic hazards for the Anchorage, Alaska area, to understand the nature of the subduction zone, and to understand the nature of stress within the subduction zone. In particular, I identify seismogenic structures, map the distribution of earthquakes, examine the location of aftershocks in the context of the Great Alaskan earthquake of 1964 and seismic hazards that manifest themselves for the population of Anchorage, Alaska. I relocate over 9000 earthquakes occurring at depths \u3e25 km in the Anchorage, Alaska region using the Double Difference earthquake relocation technique in order to identify seismic hazards. These events occurred between 1964-1999 and data are from the Alaska Earthquake Information Center (AEIC) database. In addition, I examine cross-sections of the regional seismicity in order to understand the nature of the Wadati-Benioff zone. The region is complicated by oblique subduction of the Pacific plate and the Yakutat block beneath the North American plate. Focal mechanism and stress inversion studies will yield information about regional and local stress orientations, which will be important to determining the seismic hazards. The results of this study will identify seismic source zones in the lower plate, stress variability and smaller scale structures that were not identified in previous large scale regional studies