Experimental Recreation of the Sub-Glacial System, an Analysis of Hold Time versus Strengthening to Shed Light on the Mechanics of Stick-Slip Ice Streams

dc.contributor.author McBrearty, Ian
dc.contributor.department Geological and Atmospheric Sciences
dc.date 2018-02-17T00:12:05.000
dc.date.accessioned 2020-07-07T05:11:01Z
dc.date.available 2020-07-07T05:11:01Z
dc.date.issued 2015-04-14
dc.description.abstract <p>Ice streams in Antarctica are known to move ice rapidly, in a narrow band, over a loose permeable substrate to the sea- contributing to sea-level rise and the decay of the Antarctic Ice Sheet. It has been observed that some of these ice streams move in a “stick-slip” fashion, lurching ahead small steps at a time. Past workers have proposed this observation is indicative of temporal strengthening in the ice stream when it’s sitting at rest, but have not satisfactorily concluded which components of the glacial system are directly causing the strengthening. To understand the mechanics dictating ice stream motion, and in turn put better constraints on predictions regarding the continued decay of the Antarctic Ice Sheet, we have resorted to experimentally recreating the sub-glacial system in the lab, in two “ringshear” devices designed by Dr. Iverson at Iowa State University. Two main questions we wanted answered were: (A) “Do we observe a significant relationship between hold time and strengthening?” and (B) “Which component(s) (ice, water, and sediment) contribute to the strengthening, and by how much does each contribute?” To do this we ran a suite of “slide-hold-slide” experiments, in each case adding one more component of the glacial system, where time held still (corresponding to the “stick” phase of motion), was measured against the maximum strength the material achieved upon forcing it to undergo further shear (corresponding to the “slip” phase of motion). Our results indicate that there is indeed a significant relationship between hold times and strengthening, and that all three components (ice, water, sediment) contribute to strengthening- however, with each component contributing differently depending on how long of a hold time they have undergone. These results are in agreement with first order physical principles, but further work is required to develop the mathematical relationships relating strengthening to hold time for each component of the system.</p>
dc.identifier archive/lib.dr.iastate.edu/undergradresearch_symposium/2015/presentations/19/
dc.identifier.articleid 1107
dc.identifier.contextkey 7558428
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath undergradresearch_symposium/2015/presentations/19
dc.identifier.uri https://dr.lib.iastate.edu/handle/20.500.12876/91680
dc.relation.ispartofseries Symposium on Undergraduate Research and Creative Expression
dc.source.bitstream archive/lib.dr.iastate.edu/undergradresearch_symposium/2015/presentations/19/2.D.2_20McBrearty.pdf|||Fri Jan 14 21:49:50 UTC 2022
dc.subject.disciplines Glaciology
dc.title Experimental Recreation of the Sub-Glacial System, an Analysis of Hold Time versus Strengthening to Shed Light on the Mechanics of Stick-Slip Ice Streams
dc.type event
dc.type.genre article
dspace.entity.type Publication
relation.isOrgUnitOfPublication 29272786-4c4a-4d63-98d6-e7b6d6730c45
relation.isSeriesOfPublication 6730f354-97b8-4408-bad3-7e5c3b2fca9d
thesis.degree.discipline Geology
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