Seismicity on the western Greenland Ice Sheet: Surface fracture in the vicinity of active moulins
We analyzed geophone and GPS measurements collected within the ablation zone of the western Greenland Ice Sheet during a ~35 day period of the 2011 melt season to study changes in ice deformation before, during, and after a supraglacial lake drainage event. During rapid lake drainage, ice flow speed...
Published in: | Journal of Geophysical Research: Earth Surface |
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Online Access: | http://www.osti.gov/servlets/purl/1215646 https://www.osti.gov/biblio/1215646 https://doi.org/10.1002/2014JF003398 |
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ftosti:oai:osti.gov:1215646 2023-07-30T04:03:50+02:00 Seismicity on the western Greenland Ice Sheet: Surface fracture in the vicinity of active moulins Carmichael, Joshua D. Joughin, Ian Behn, Mark D. Das, Sarah King, Matt A. Stevens, Laura Lizarralde, Dan 2022-05-20 application/pdf http://www.osti.gov/servlets/purl/1215646 https://www.osti.gov/biblio/1215646 https://doi.org/10.1002/2014JF003398 unknown http://www.osti.gov/servlets/purl/1215646 https://www.osti.gov/biblio/1215646 https://doi.org/10.1002/2014JF003398 doi:10.1002/2014JF003398 54 ENVIRONMENTAL SCIENCES 58 GEOSCIENCES 97 MATHEMATICS AND COMPUTING 2022 ftosti https://doi.org/10.1002/2014JF003398 2023-07-11T09:02:58Z We analyzed geophone and GPS measurements collected within the ablation zone of the western Greenland Ice Sheet during a ~35 day period of the 2011 melt season to study changes in ice deformation before, during, and after a supraglacial lake drainage event. During rapid lake drainage, ice flow speeds increased to ~400% of winter values, and icequake activity peaked. At times >7 days after drainage, this seismicity developed variability over both diurnal and longer periods (~10 days), while coincident ice speeds fell to ~150% of winter values and showed nightly peaks in spatial variability. Approximately 95% of all detected seismicity in the lake basin and its immediate vicinity was triggered by fracture propagation within near-surface ice (<330 m deep) that generated Rayleigh waves. Icequakes occurring before and during drainage frequently were collocated with the down flow (west) end of the primary hydrofracture through which the lake drained but shifted farther west and outside the lake basin after the drainage. We interpret these results to reveal vertical hydrofracture opening and local uplift during the drainage, followed by enhanced seismicity and ice flow on the downstream side of the lake basin. This region collocates with interferometric synthetic aperture radar-measured speedup in previous years and could reflect the migration path of the meltwater supplied to the bed by the lake. The diurnal seismic signal can be associated with nightly reductions in surface melt input that increase effective basal pressure and traction, thereby promoting elevated strain in the surficial ice. Other/Unknown Material Greenland Ice Sheet SciTec Connect (Office of Scientific and Technical Information - OSTI, U.S. Department of Energy) Greenland Rapid Lake ENVELOPE(177.619,177.619,52.064,52.064) Journal of Geophysical Research: Earth Surface 120 6 1082 1106 |
institution |
Open Polar |
collection |
SciTec Connect (Office of Scientific and Technical Information - OSTI, U.S. Department of Energy) |
op_collection_id |
ftosti |
language |
unknown |
topic |
54 ENVIRONMENTAL SCIENCES 58 GEOSCIENCES 97 MATHEMATICS AND COMPUTING |
spellingShingle |
54 ENVIRONMENTAL SCIENCES 58 GEOSCIENCES 97 MATHEMATICS AND COMPUTING Carmichael, Joshua D. Joughin, Ian Behn, Mark D. Das, Sarah King, Matt A. Stevens, Laura Lizarralde, Dan Seismicity on the western Greenland Ice Sheet: Surface fracture in the vicinity of active moulins |
topic_facet |
54 ENVIRONMENTAL SCIENCES 58 GEOSCIENCES 97 MATHEMATICS AND COMPUTING |
description |
We analyzed geophone and GPS measurements collected within the ablation zone of the western Greenland Ice Sheet during a ~35 day period of the 2011 melt season to study changes in ice deformation before, during, and after a supraglacial lake drainage event. During rapid lake drainage, ice flow speeds increased to ~400% of winter values, and icequake activity peaked. At times >7 days after drainage, this seismicity developed variability over both diurnal and longer periods (~10 days), while coincident ice speeds fell to ~150% of winter values and showed nightly peaks in spatial variability. Approximately 95% of all detected seismicity in the lake basin and its immediate vicinity was triggered by fracture propagation within near-surface ice (<330 m deep) that generated Rayleigh waves. Icequakes occurring before and during drainage frequently were collocated with the down flow (west) end of the primary hydrofracture through which the lake drained but shifted farther west and outside the lake basin after the drainage. We interpret these results to reveal vertical hydrofracture opening and local uplift during the drainage, followed by enhanced seismicity and ice flow on the downstream side of the lake basin. This region collocates with interferometric synthetic aperture radar-measured speedup in previous years and could reflect the migration path of the meltwater supplied to the bed by the lake. The diurnal seismic signal can be associated with nightly reductions in surface melt input that increase effective basal pressure and traction, thereby promoting elevated strain in the surficial ice. |
author |
Carmichael, Joshua D. Joughin, Ian Behn, Mark D. Das, Sarah King, Matt A. Stevens, Laura Lizarralde, Dan |
author_facet |
Carmichael, Joshua D. Joughin, Ian Behn, Mark D. Das, Sarah King, Matt A. Stevens, Laura Lizarralde, Dan |
author_sort |
Carmichael, Joshua D. |
title |
Seismicity on the western Greenland Ice Sheet: Surface fracture in the vicinity of active moulins |
title_short |
Seismicity on the western Greenland Ice Sheet: Surface fracture in the vicinity of active moulins |
title_full |
Seismicity on the western Greenland Ice Sheet: Surface fracture in the vicinity of active moulins |
title_fullStr |
Seismicity on the western Greenland Ice Sheet: Surface fracture in the vicinity of active moulins |
title_full_unstemmed |
Seismicity on the western Greenland Ice Sheet: Surface fracture in the vicinity of active moulins |
title_sort |
seismicity on the western greenland ice sheet: surface fracture in the vicinity of active moulins |
publishDate |
2022 |
url |
http://www.osti.gov/servlets/purl/1215646 https://www.osti.gov/biblio/1215646 https://doi.org/10.1002/2014JF003398 |
long_lat |
ENVELOPE(177.619,177.619,52.064,52.064) |
geographic |
Greenland Rapid Lake |
geographic_facet |
Greenland Rapid Lake |
genre |
Greenland Ice Sheet |
genre_facet |
Greenland Ice Sheet |
op_relation |
http://www.osti.gov/servlets/purl/1215646 https://www.osti.gov/biblio/1215646 https://doi.org/10.1002/2014JF003398 doi:10.1002/2014JF003398 |
op_doi |
https://doi.org/10.1002/2014JF003398 |
container_title |
Journal of Geophysical Research: Earth Surface |
container_volume |
120 |
container_issue |
6 |
container_start_page |
1082 |
op_container_end_page |
1106 |
_version_ |
1772814956477022208 |