Crustal And Lithospheric Thickness Variations For Central Alaska And The Chugach-St. Elias Region From P and S Receiver Functions

During the summers of 2005 and 2006, 22 broadband seismic stations were installed in the Saint Elias and Chugach terranes of south-central Alaska as part of the Saint Elias Erosion and Tectonics Project (STEEP). We computed P and S receiver functions from these stations and an additional 35 broadband stations in the Alaska seismic network. The method applied here uses deconvolution of the earth's impulse response by means of a Wiener filter. The deconvolution is stabilized by pre-whitening of the autocorrelation matrix. Receiver functions produced for stations located on the Yakutat Block consistently exhibit forms that repeat with a 3 second period making the identification of a clear moho conversion difficult. This would be consistent with multiples produced within the layer of sedimentary rock that covers the terrane. Furthermore, observed P receiver functions show clear back-azimuthal dependency. The computation of S receiver functions will greatly enhance our knowledge of the lithospheric structure in this region.