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Accelerated subglacial erosion in response to stick-slip motion

L. K. Zoet, R. B. Alley, S. Anandakrishnan and K. Christianson
Accelerated subglacial erosion in response to stick-slip motion
Geology (Boulder) (November 2012) 41 (2): 159-162

Abstract

Subglacial stick-slip motion speeds erosion by hydrofracturing and in other ways, as determined from analysis of the growing body of field data. Microearthquake monitoring commonly detects subglacial earthquakes, likely mostly from stick-slip motion of debris-laden ice over bedrock. Source parameters show that many quakes cause enough motion to greatly lower water pressure in cavities on the lee sides of bedrock steps. We calculate that the resulting expansion of higher-pressure water in nearby cracks promotes hydrofracturing, with even relatively small cracks growing unstably under thick glaciers and all cracks growing faster than for aseismic behavior. This mechanism also helps generate the step-like topography favoring block plucking. This stick-slip glacier-erosion hypothesis suggests that the erosion rate will increase with ice thickness as well as basal shear stress, ice-flow velocity, and water supply.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 41
Serial Issue: 2
Title: Accelerated subglacial erosion in response to stick-slip motion
Affiliation: Pennsylvania State University, Department of Geosciences, University Park, PA, United States
Pages: 159-162
Published: 20121106
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 48
Accession Number: 2013-009544
Categories: Quaternary geologySeismology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2013039
Illustration Description: illus.
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201307
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