Tremor during ice-stream stick slip
During the 200 km-scale stick slip of the Whillans Ice Plain (WIP), West Antarctica, seismic tremor episodes occur at the ice–bed interface. We interpret these tremor episodes as swarms of small repeating earthquakes. The earthquakes are evenly spaced in time, and this even spacing gives rise to spe...
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Copernicus Publications
2016
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Online Access: | https://doi.org/10.5194/tc-10-385-2016 http://www.the-cryosphere.net/10/385/2016/tc-10-385-2016.pdf https://doaj.org/article/76e88108870f4650971d956ba1fe4987 |
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fttriple:oai:gotriple.eu:oai:doaj.org/article:76e88108870f4650971d956ba1fe4987 2023-05-15T13:36:22+02:00 Tremor during ice-stream stick slip B. P. Lipovsky E. M. Dunham 2016-02-01 https://doi.org/10.5194/tc-10-385-2016 http://www.the-cryosphere.net/10/385/2016/tc-10-385-2016.pdf https://doaj.org/article/76e88108870f4650971d956ba1fe4987 en eng Copernicus Publications 1994-0416 1994-0424 doi:10.5194/tc-10-385-2016 http://www.the-cryosphere.net/10/385/2016/tc-10-385-2016.pdf https://doaj.org/article/76e88108870f4650971d956ba1fe4987 undefined The Cryosphere, Vol 10, Iss 1, Pp 385-399 (2016) geo envir Journal Article https://vocabularies.coar-repositories.org/resource_types/c_6501/ 2016 fttriple https://doi.org/10.5194/tc-10-385-2016 2023-01-22T19:33:31Z During the 200 km-scale stick slip of the Whillans Ice Plain (WIP), West Antarctica, seismic tremor episodes occur at the ice–bed interface. We interpret these tremor episodes as swarms of small repeating earthquakes. The earthquakes are evenly spaced in time, and this even spacing gives rise to spectral peaks at integer multiples of the recurrence frequency ∼ 10–20 Hz. We conduct numerical simulations of the tremor episodes that include the balance of forces acting on the fault, the evolution of rate- and state-dependent fault friction, and wave propagation from the fault patch to a seismometer located on the ice. The ice slides as an elastic block loaded by the push of the upstream ice, and so the simulated basal fault patch experiences a loading velocity equal to the velocity observed by GPS receivers on the surface of the WIP. By matching synthetic seismograms to observed seismograms, we infer fault patch area ∼ 10 m2, bed shear modulus ∼ 20 MPa, effective pressure ∼ 10 kPa, and frictional state evolution distance ∼ 1 μm. Large-scale slip events often occur twice daily, although skipped events have been increasing in frequency over the last decade. The amplitude of tremor (recorded by seismometers on the ice surface) is greater during the double wait time events that follow skipped events. The physical mechanism responsible for these elevated amplitudes may provide a window into near-future subglacial conditions and the processes that occur during ice-stream stagnation. Article in Journal/Newspaper Antarc* Antarctica The Cryosphere West Antarctica Unknown West Antarctica Whillans ENVELOPE(-64.250,-64.250,-84.450,-84.450) The Cryosphere 10 1 385 399 |
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Open Polar |
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Unknown |
op_collection_id |
fttriple |
language |
English |
topic |
geo envir |
spellingShingle |
geo envir B. P. Lipovsky E. M. Dunham Tremor during ice-stream stick slip |
topic_facet |
geo envir |
description |
During the 200 km-scale stick slip of the Whillans Ice Plain (WIP), West Antarctica, seismic tremor episodes occur at the ice–bed interface. We interpret these tremor episodes as swarms of small repeating earthquakes. The earthquakes are evenly spaced in time, and this even spacing gives rise to spectral peaks at integer multiples of the recurrence frequency ∼ 10–20 Hz. We conduct numerical simulations of the tremor episodes that include the balance of forces acting on the fault, the evolution of rate- and state-dependent fault friction, and wave propagation from the fault patch to a seismometer located on the ice. The ice slides as an elastic block loaded by the push of the upstream ice, and so the simulated basal fault patch experiences a loading velocity equal to the velocity observed by GPS receivers on the surface of the WIP. By matching synthetic seismograms to observed seismograms, we infer fault patch area ∼ 10 m2, bed shear modulus ∼ 20 MPa, effective pressure ∼ 10 kPa, and frictional state evolution distance ∼ 1 μm. Large-scale slip events often occur twice daily, although skipped events have been increasing in frequency over the last decade. The amplitude of tremor (recorded by seismometers on the ice surface) is greater during the double wait time events that follow skipped events. The physical mechanism responsible for these elevated amplitudes may provide a window into near-future subglacial conditions and the processes that occur during ice-stream stagnation. |
format |
Article in Journal/Newspaper |
author |
B. P. Lipovsky E. M. Dunham |
author_facet |
B. P. Lipovsky E. M. Dunham |
author_sort |
B. P. Lipovsky |
title |
Tremor during ice-stream stick slip |
title_short |
Tremor during ice-stream stick slip |
title_full |
Tremor during ice-stream stick slip |
title_fullStr |
Tremor during ice-stream stick slip |
title_full_unstemmed |
Tremor during ice-stream stick slip |
title_sort |
tremor during ice-stream stick slip |
publisher |
Copernicus Publications |
publishDate |
2016 |
url |
https://doi.org/10.5194/tc-10-385-2016 http://www.the-cryosphere.net/10/385/2016/tc-10-385-2016.pdf https://doaj.org/article/76e88108870f4650971d956ba1fe4987 |
long_lat |
ENVELOPE(-64.250,-64.250,-84.450,-84.450) |
geographic |
West Antarctica Whillans |
geographic_facet |
West Antarctica Whillans |
genre |
Antarc* Antarctica The Cryosphere West Antarctica |
genre_facet |
Antarc* Antarctica The Cryosphere West Antarctica |
op_source |
The Cryosphere, Vol 10, Iss 1, Pp 385-399 (2016) |
op_relation |
1994-0416 1994-0424 doi:10.5194/tc-10-385-2016 http://www.the-cryosphere.net/10/385/2016/tc-10-385-2016.pdf https://doaj.org/article/76e88108870f4650971d956ba1fe4987 |
op_rights |
undefined |
op_doi |
https://doi.org/10.5194/tc-10-385-2016 |
container_title |
The Cryosphere |
container_volume |
10 |
container_issue |
1 |
container_start_page |
385 |
op_container_end_page |
399 |
_version_ |
1766077640035270656 |