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| Titel |
Reduced glacier sliding caused by persistent drainage from a subglacial lake |
| VerfasserIn |
E. Magnusson, H. Björnsson, H. Rott, F. Pálsson |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1994-0416
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| Digitales Dokument |
URL |
| Erschienen |
In: The Cryosphere ; 4, no. 1 ; Nr. 4, no. 1 (2010-01-15), S.13-20 |
| Datensatznummer |
250001542
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| Publikation (Nr.) |
 copernicus.org/tc-4-13-2010.pdf |
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| Zusammenfassung |
| We present velocity observations of a glacier outlet in Vatnajökull,
Iceland, deduced from interferometric SAR (InSAR) data obtained during the
ERS1/2 tandem mission in 1995–2000. More than a 50% decrease in glacier
velocity was observed subsequent to a large jökulhlaup from the
subglacial lake Grímsvötn in 1996. The glacier had not reached its
former flow rate in 2000. The jökulhlaup damaged the lake's ice-dam
causing persistent drainage from the lake. InSAR based studies of water
accumulation within Grímsvötn suggest that a leakage of >3 m3 s−1
prevailed throughout our study period. We suggest that the
lake leakage kept open a tunnel at low water pressure underneath the whole
length of the glacier. The tunnel flow drained water from its surroundings,
hence lowering the water pressure of a distributed drainage system,
underneath the upper and centre parts of the glacier, which prior to the
jökulhlaup sustained significant basal sliding. This is in accordance
with theoretical prediction that tunnel flow in a steady state may cause
slow-down in glacier velocity by reducing the subglacial water pressure. The
width of the affected areas was ~5 km on the upper part of the glacier
and ~8 km on the centre part of the glacier. This indicates that the
water pressure reduction propagates laterally from the tunnel over a
distance of a few km. |
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