Teleseismic Earthquake Signals Observed on an Ice Shelf

Friday, 18 December 2015: 11:35
307 (Moscone South)
Michael G Baker1, Richard C Aster2, Robert E Anthony3, Doug Wiens4, Andrew Nyblade5, Peter D Bromirski6, Ralph A Stephen7 and Peter Gerstoft6, (1)Colorado State University, Fort Collins, CO, United States, (2)Colorado State University, Geosciences Department, Fort Collins, CO, United States, (3)New Mexico Tech, Socorro, NM, United States, (4)Washington University in St Louis, Department of Earth and Planetary Sciences, St. Louis, MO, United States, (5)Penn St Univ, University Park, PA, United States, (6)University of California San Diego, La Jolla, CA, United States, (7)Woods Hole Oceanographic Institution, Woods Hole, MA, United States
The West Antarctic Rift System (WARS) is one of Earth’s largest continental extension zones. Study of the WARS is complicated by the presence of the West Antarctic Ice Sheet, the Ross Ice Shelf, and the Ross Sea. Recent deployments of broadband seismographs in the POLENET project have allowed passive seismic techniques, such as receiver function analysis and surface wave dispersion, to be widely utilized to infer crustal and mantle velocity structure across much of the WARS and West Antarctica. However, a large sector of the WARS lies beneath the Ross Ice Shelf. In late 2014, 34 broadband seismographs were deployed atop the ice shelf to jointly study deep Earth structure and the dynamics of the ice shelf. Ice shelf conditions present strong challenges to broadband teleseismic imaging: 1) The presence of complicating signals in the microseism through long-period bands due to the influence of ocean gravity waves; 2) The strong velocity contrasts at the ice-water and water-sediment interfaces on either side of the water layer give rise to large amplitude reverberations; 3) The water layer screens S-waves or P-to-S phases originating from below the water layer. We present an initial analysis of the first teleseismic earthquake arrivals collected on the ice shelf at the end of the 2014 field season from a limited subset of these stations.