A seismic investigation of basal conditions in glaciated regions

Open Access
Author:
Peters, Leo Everett
Graduate Program:
Geosciences
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
August 14, 2009
Committee Members:
  • Sridhar Anandakrishnan, Dissertation Advisor
  • Sridhar Anandakrishnan, Committee Chair
  • Richard B Alley, Committee Member
  • Charles James Ammon, Committee Member
  • Charles Holland, Committee Member
Keywords:
  • glaciology
  • AVO analysis
  • basal conditions
  • seismology
Abstract:
Seismic amplitude analysis of the ice bottom reflector is an effective way to constrain the basal regime of glaciated regions and better capture the role of the bed in ice dynamics. The strength and phase of this observed ice bottom reflection, and its variations when analyzed over a range of source-receiver offsets, relate to a unique set of elastic properties at the ice-bed interface that highlight the material properties of the subglacial bed. These observations allow us to obtain a greater understanding its role in facilitating ice drainage from the interior of the earth's ice sheets to the margins. This thesis builds upon the seismic amplitude variation with offset (AVO) technique to exploit seismic observations of the ice-bed interface to determine basal conditions. The primary goal of this thesis is to outline the overall approach for extracting the elastic properties of the subglacial bed from an observed seismic reflection, touching upon the various simplifications and shortcomings experienced along the way. The secondary goal is to highlight the robustness of seismic AVO analysis in glaciated regions by applying this technique to seismic reflection data from four locations in Antarctica and Greenland. Each example provides a different snapshot of the basal regime, revealing a subglacial system with various structural, mechanical, and hydrological components at work in shaping the evolution of ice dynamics within the earth's ice sheets.