Seismic Investigation of Sediments Beneath Antarctic Ice Streams
Open Access
- Author:
- Luthra, Tarun
- Graduate Program:
- Earth Sciences
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- March 01, 2017
- Committee Members:
- Sridhar Anandakrishnan, Dissertation Advisor/Co-Advisor
Sridhar Anandakrishnan, Committee Chair/Co-Chair
Richard B Alley, Committee Member
Byron Richard Parizek, Committee Member
Charles Holland, Outside Member - Keywords:
- Glaciology
Ice Streams
Geophysics
Reflection seismology
geosciences
Antarctica
West Antarctic Ice Sheet - Abstract:
- An accurate knowledge of the subglacial system is key in elucidating the mechanisms of ice stream motion and overall mass balance of the Antarctic Ice Sheet. Ice streams, owing to their geometry and low surface slopes, generate really low driving stress, thus typically require an extensive deformable subglacial sediment layer to allow fast flow conditions. This thin layer of sediment is highly sensitive to subglacial water pressure, which, if reduced, can dramatically alter the flow dynamics of ice streams. The flow regime of Whillans Ice Stream and Kamb Ice Stream highlight these basal conditions. Kamb Ice Stream stagnated about 150 years ago while current observations of the Whillans Ice Stream show that the ice stream is decelerating in the past few decades. Both attribute their current flow conditions to the presence of areas of high basal drag or the so-called ‘sticky spots’, which inhibit fast ice stream flow. This subglacial interface is highly influenced by the sediment porosity, fluid pressure, and water content which ultimately defines its overall strength in restricting the ice-stream flow. In this thesis, I employ the seismic amplitude analysis technique to study the subglacial interface of these two ice streams. The seismic amplitude analysis provides an insight into the subglacial regimes of ice stream flow in Antarctica. The knowledge about this subglacial interface and ground truthing of bed conditions is essential for the ice sheet models and discerning ice dynamics to understand the future evolution of these ice streams.