Background

The Antarctic crust and mantle compostion and geometry are poorly known. The primary tool for sounding the crust, upper mantle, and the deeper aesthenosphere is interpretation of seismic data; either ``active'' through use of explosives or ``passive'' using natural sources and interpreting various earthquake phase arrival times and amplitudes. Integrating passive and active seismology can result in efficient use of resources to produce detailed images of the lithosphere. In this proposal the need for passive seismology in Antarctica is addressed.

The Antarctic is a gaping hole in the rapidly improving field of global seismic imaging and tomography. On this huge continent (surface area of 14 M km2) there are only eight broadband seismic observatories. Further, all of those stations are along the margins of the continent (except for SPA at S. Pole) and none is in the West Antarctic. By contrast, there are 200 permanent stations worldwide in the FDSN (Federation of Digital Seismograph Networks) and O(104) in national networks not yet integrated into the FDSN. There have been innumerable temporary deployments (1--5 years) through PASSCAL (Program for Array Seismic Studies of the Continental Lithosphere), but which have rarely been attempted in the Antarctic. The obvious reason for this lack of data from the interior is the need to supply power continuously and store data onsite during the dark winter months.

As part of the Anubis project I will deploy 12 broadband seismic stations on the continent itself. Because 98% of the continent is ice covered, these stations will be installed at the surface of the ice sheet. The body-wave data thus recorded from regional and teleseismic earthquakes can be analyzed at each station for local crustal thickness, lamination, Poisson's ratio (a measure of crustal composition), crust and mantle anisotropy (a measure of current and former stress regimes), and identification of rift zones and crustal block boundaries. In addition, the data from all the stations (including the existing peripheral ones) can be used for seismic tomographic analysis to detail lateral variations in these properties.


Sridhar Anandakrishnan <sak@essc.psu.edu>
Last modified: Fri Dec 18 14:07:33 EST 1998