Changes in jökulhlaup sizes in Grímsvötn, Vatnajökull, Iceland, 1934-91, deduced from in-situ measurements of subglacial lake volume
Abstract A record of volumes of jökulhlaups from the subglacial Grímsvötn lake, Vatnajökull, Iceland, has been derived for the period 1934–91. The change in lake volume during jökulhlaups is estimated from the lake area, ice-cover thickness and the drop in lake level. The jökulhlaup volumes have dec...
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Cambridge University Press (CUP)
1995
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Online Access: | http://dx.doi.org/10.1017/s0022143000016166 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000016166 |
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crcambridgeupr:10.1017/s0022143000016166 2024-03-03T08:45:29+00:00 Changes in jökulhlaup sizes in Grímsvötn, Vatnajökull, Iceland, 1934-91, deduced from in-situ measurements of subglacial lake volume Gudmundsson, Magnús T. Björnsson, Helgi Pálsson, Finnur 1995 http://dx.doi.org/10.1017/s0022143000016166 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000016166 en eng Cambridge University Press (CUP) Journal of Glaciology volume 41, issue 138, page 263-272 ISSN 0022-1430 1727-5652 Earth-Surface Processes journal-article 1995 crcambridgeupr https://doi.org/10.1017/s0022143000016166 2024-02-08T08:32:56Z Abstract A record of volumes of jökulhlaups from the subglacial Grímsvötn lake, Vatnajökull, Iceland, has been derived for the period 1934–91. The change in lake volume during jökulhlaups is estimated from the lake area, ice-cover thickness and the drop in lake level. The jökulhlaup volumes have decreased gradually during this period of low volcanic activity and declining geothermal power. The two jökulhlaups in the 1930s each discharged about 4.5 km 3 (peak discharge 25-30 × 10 3 m 3 s −1 ). In the 1980s, jökulhlaup volumes were 0.6.-1.2 km 3 (peak discharge 2 × 10 3 m 3 s −1 ). The lake level required to trigger a jökulhlaup has risen as an ice dam east of the lake has thickened. Water flow in a jökulhlaup ceases when the base of a floating ice shelf covering Grímsvötn settles to about 1160 m a.s.l. Apparently, the jökulhlaups are cut off when the base of the ice shelf collapses on to a subglacial ridge bordering the lake on its eastern side. The decline in melting rates has resulted in a positive mass balance of the 160-170 km 2 Grímsvötn ice-drainage basin. Comparison of maps shows that the average positive mass-balance rate was 0.12 km 3 a −1 (25% of the total accumulation) in the period 1946-87. A gradually increasing positive mass balance has prevailed since 1954, reaching 0.23 km 3 a −1 in 1976-86 (48% of total accumulation). Article in Journal/Newspaper Ice Shelf Iceland Journal of Glaciology Vatnajökull Cambridge University Press Vatnajökull ENVELOPE(-16.823,-16.823,64.420,64.420) Journal of Glaciology 41 138 263 272 |
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Cambridge University Press |
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crcambridgeupr |
language |
English |
topic |
Earth-Surface Processes |
spellingShingle |
Earth-Surface Processes Gudmundsson, Magnús T. Björnsson, Helgi Pálsson, Finnur Changes in jökulhlaup sizes in Grímsvötn, Vatnajökull, Iceland, 1934-91, deduced from in-situ measurements of subglacial lake volume |
topic_facet |
Earth-Surface Processes |
description |
Abstract A record of volumes of jökulhlaups from the subglacial Grímsvötn lake, Vatnajökull, Iceland, has been derived for the period 1934–91. The change in lake volume during jökulhlaups is estimated from the lake area, ice-cover thickness and the drop in lake level. The jökulhlaup volumes have decreased gradually during this period of low volcanic activity and declining geothermal power. The two jökulhlaups in the 1930s each discharged about 4.5 km 3 (peak discharge 25-30 × 10 3 m 3 s −1 ). In the 1980s, jökulhlaup volumes were 0.6.-1.2 km 3 (peak discharge 2 × 10 3 m 3 s −1 ). The lake level required to trigger a jökulhlaup has risen as an ice dam east of the lake has thickened. Water flow in a jökulhlaup ceases when the base of a floating ice shelf covering Grímsvötn settles to about 1160 m a.s.l. Apparently, the jökulhlaups are cut off when the base of the ice shelf collapses on to a subglacial ridge bordering the lake on its eastern side. The decline in melting rates has resulted in a positive mass balance of the 160-170 km 2 Grímsvötn ice-drainage basin. Comparison of maps shows that the average positive mass-balance rate was 0.12 km 3 a −1 (25% of the total accumulation) in the period 1946-87. A gradually increasing positive mass balance has prevailed since 1954, reaching 0.23 km 3 a −1 in 1976-86 (48% of total accumulation). |
format |
Article in Journal/Newspaper |
author |
Gudmundsson, Magnús T. Björnsson, Helgi Pálsson, Finnur |
author_facet |
Gudmundsson, Magnús T. Björnsson, Helgi Pálsson, Finnur |
author_sort |
Gudmundsson, Magnús T. |
title |
Changes in jökulhlaup sizes in Grímsvötn, Vatnajökull, Iceland, 1934-91, deduced from in-situ measurements of subglacial lake volume |
title_short |
Changes in jökulhlaup sizes in Grímsvötn, Vatnajökull, Iceland, 1934-91, deduced from in-situ measurements of subglacial lake volume |
title_full |
Changes in jökulhlaup sizes in Grímsvötn, Vatnajökull, Iceland, 1934-91, deduced from in-situ measurements of subglacial lake volume |
title_fullStr |
Changes in jökulhlaup sizes in Grímsvötn, Vatnajökull, Iceland, 1934-91, deduced from in-situ measurements of subglacial lake volume |
title_full_unstemmed |
Changes in jökulhlaup sizes in Grímsvötn, Vatnajökull, Iceland, 1934-91, deduced from in-situ measurements of subglacial lake volume |
title_sort |
changes in jökulhlaup sizes in grímsvötn, vatnajökull, iceland, 1934-91, deduced from in-situ measurements of subglacial lake volume |
publisher |
Cambridge University Press (CUP) |
publishDate |
1995 |
url |
http://dx.doi.org/10.1017/s0022143000016166 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000016166 |
long_lat |
ENVELOPE(-16.823,-16.823,64.420,64.420) |
geographic |
Vatnajökull |
geographic_facet |
Vatnajökull |
genre |
Ice Shelf Iceland Journal of Glaciology Vatnajökull |
genre_facet |
Ice Shelf Iceland Journal of Glaciology Vatnajökull |
op_source |
Journal of Glaciology volume 41, issue 138, page 263-272 ISSN 0022-1430 1727-5652 |
op_doi |
https://doi.org/10.1017/s0022143000016166 |
container_title |
Journal of Glaciology |
container_volume |
41 |
container_issue |
138 |
container_start_page |
263 |
op_container_end_page |
272 |
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1792501048311545856 |