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Glacier slip and seismicity induced by surface melt

Peter L. Moore, J. Paul Winberry, Neal R. Iverson, Knut A. Christianson, Sridhar Anandakrishnan, Miriam Jackson, Mark E. Mathison and Denis Cohen
Glacier slip and seismicity induced by surface melt
Geology (Boulder) (October 2013) 41 (12): 1247-1250

Abstract

Many of the key processes governing fast glacier flow involve interaction between a glacier and its basal hydrological system, which is hidden from direct observation. Passive seismic monitoring has shown promise as a tool for remotely monitoring basal processes, but lack of glacier-bed access prevents clear understanding of the relationships between subglacial processes and corresponding seismic emissions. Here we describe direct measurements of basal hydrology, sliding, and broadband seismicity made in a unique subglacial facility in Norway during the onset of two summer melt seasons. In the most pronounced of these episodes, rapid delivery of surface meltwater to the bed briefly enhanced basal slip following a period of elevated high-frequency seismic activity related to surface crevassing. Subsequent ground tilt derived from ultralong-period seismic signals was associated with subglacial bedrock deformation during transient pressurization of the basal hydraulic system. These signals are interpreted to represent hydraulic jacking as the supply of water to the bed exceeded the capacity of the hydraulic system. Enhanced slip terminated 2.5 h after it started, when ice-bed decoupling or increased connectivity in the basal cavity network relieved cavity overpressure. The results support theoretical models for hydraulic jacking and illustrate how melt-induced increases in speed can be short lived if cavity growth or ice-bed decoupling allows basal water more efficient drainage.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 41
Serial Issue: 12
Title: Glacier slip and seismicity induced by surface melt
Affiliation: Iowa State University, Department of Geological and Atmospheric Science, Ames, IA, United States
Pages: 1247-1250
Published: 20131016
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 20
Accession Number: 2013-084961
Categories: Quaternary geologyApplied geophysics
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2013349
Illustration Description: illus. incl. sketch map
N66°40'12" - N66°40'21", E13°47'24" - E13°47'24"
Secondary Affiliation: Central Washington University, USA, United StatesSt. Olaf College, USA, United StatesPennsylvania State University, USA, United StatesNorwegian Water Resources and Energy Directorate, NOR, Norway
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: 201350
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