Tidal and Structural Controls on Seismic Events Near the Grounding Line at Beardmore Glacier, Antarctica

• Main Author: Cooley, Jade
• Format: Text
• Language: English
• Published: ScholarWorks@CWU 2017
• Subjects: cryoseismology; Ross Ice Shelf; icequakes; buttressing; GPS; Geophysics and Seismology; Glaciology; Austral; Beardmore; Beardmore Glacier; Antarc*; Antarctica; Ice Shelf
• Online Access: https://digitalcommons.cwu.edu/etd/700; https://digitalcommons.cwu.edu/cgi/viewcontent.cgi?article=1716&context=etd

Here I report seismic events occurring over a three-week period during the 2013-2014 austral summer near the grounding line of Beardmore Glacier, Antarctica. The ~24000 events over this time frame had a noticeable temporal pattern that correlates well with the principally diurnal tides of Antarctica. Falling and rising tide each accounted for nearly equal occurrence of events, and most (~42%) events occurred in the last third of any tidal cycle. Event epicenters were located using beamforming, and display a spatial pattern of two distinct clusters. Appearance of event location clusters differ on rising and falling tide. I theorize that, due to direction of glacier outlet and direction of overall ice shelf flow, the Beardmore Glacier can be separated into two zones near its grounding line that explain this pattern. There is an extensional zone which experiences most stress during falling tide, and a compressional zone that undergoes stress during both falling and rising tide.