Seismological Experiment across the Wilkes Subglacial Basin and Adjacent Transantactic Mountains

Abstract

During the Itali-Antartide XXI Antarctic expedition (October 2005 – February 2006), an experiment of passive seismology was carried out in the framework of the WISE Project. The main targets of the experiment, devoted to the recording of teleseismic events, were to: - reconstruct the deep structure (Moho and other possibile seismic discontinuities) of the Wilkes Subglacial Basin (WSB); - single out the presence and the tickness of a possibile sedimentary layer in the Wilkes Subglacial Basin (Ferraccioli et al., 2001; Studinges et al., 2004), thereby also providing independent constraints for the interpretation of new aerogeophysical data over the study region (Ferraccioli et a., this volume). Installation and maintenance was made in conjunction with the GDS (Geomagnetic Depth Sounding) team (Armadillo et al., this volume), as in each site there was a seismic and a GDS station. The transportation required the use of helicopters for the locations on the Transantactic Mountains (TAM) (S01 and S02) and of a Twin Otter for the other three sites (S03, S04 and S05). More than three hours flight were required to reach S05 from Mario Zuccheri Station (MZS). On the basis of the seismological results of the previous 2003-2004 WIBEM project, we decided to extend the exploration of the WSB further to the West, while repeating the data acquisition across the adjacent TAM, where these results were more uncertain (Piana Agostinetti et al., 2005). The data analysis is based on the Receiver Function (RF) tecnique (Langston, 1979; Piana Agostinetti et al., 2004) that allows deep crustal and upper mantle structure exploration on the basis of teleseismic data received by single stations. The RF is composite of P to S converted waves that reverberate in the structure beneath the seismometer (Ammon et al., 1990). The arrival times and the amplitudes of the converted phase depend on the depth of the velocity contrast under the frequency deconvolution of vertical from radial and transverse components. For estimating the sedimentary layer thickness, we will follow the approach developed by Anandakrishnan & Winberry (2004)