Analysis of Subglacial Sediment Properties in West Antarctica Using Seismic Amplitude Data

Open Access
Author:
Marten, Jacob Patrick
Graduate Program:
Geosciences
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
July 03, 2017
Committee Members:
  • Sridhar Anandakrishnan, Thesis Advisor
  • Richard B Alley, Committee Member
  • Charles James Ammon, Committee Member
Keywords:
  • AVO
  • Seismic
  • West Antarctic Ice Sheet
  • Antarctica
  • Reflection seismology
Abstract:
The West Antarctic Ice Sheet (WAIS) is an unstable continental ice sheet, with an ice-volume equivalent to 5 meters of global sea-level rise. This study uses reflection seismic surveys shot in proximity to the West Antarctic Ice Sheet Divide Core to estimate rock properties (p-wave velocity, s-wave velocity, and density) of the material underlying the ice sheet. Estimation of these parameters are done by picking amplitudes from the ice-bottom reflector, and analyzing their variation with offset (AVO.) This AVO response is dependent on the rock properties of the two materials at the interface (ice and underlying sediment.) Since we know the rock properties of ice, we can hold those values constant and iterate through possible rock properties of the underlying material to find a best fit. The resulting parameters from our study suggests that the material underlying the WAIS Divide Ice Core is poorly consolidated, and water saturated, sediment. A recent paper by DeConto and Pollard (2016) models the future of WAIS, and suggests a retreat of the ice sheet that puts the WAIS Ice Divide Core in close proximity to the ocean. The saturated conditions of the subglacial sediment suggested by this study, and the lack of ice previously present between the field site and ocean, would lead to conditions which may accelerate ice flow velocity and ice mass loss.