Temporal Gravity Variations near Shrinking Vatnajökull Ice Cap, Iceland
Repeated gravity measurements were carried out from 1991 until 1999 at sites SE of Vatnajökull, Iceland, to estimate the mass flow and deformation accompanying the shrinking of the ice cap. Published GPS data show an uplift of about 13 ± 5 mm/a near the ice margin. A gravity decrease of –2 ± 1 μGal/...
Published in: | Pure and Applied Geophysics |
---|---|
Main Authors: | , , , , , , , , , |
Other Authors: | |
Format: | Article in Journal/Newspaper |
Language: | unknown |
Published: |
2009
|
Subjects: | |
Online Access: | https://gfzpublic.gfz-potsdam.de/pubman/item/item_239307 |
id |
ftgfzpotsdam:oai:gfzpublic.gfz-potsdam.de:item_239307 |
---|---|
record_format |
openpolar |
spelling |
ftgfzpotsdam:oai:gfzpublic.gfz-potsdam.de:item_239307 2023-05-15T16:38:11+02:00 Temporal Gravity Variations near Shrinking Vatnajökull Ice Cap, Iceland Jacoby, W. Hartmann, O. Wallner, H. Smilde, P. Bürger, S. Sjöberg, L. Erlingsson, S. Wolf, D. Klemann, V. Sasgen, I. 1.3 Earth System Modelling, 1.0 Geodesy and Remote Sensing, Departments, GFZ Publication Database, Deutsches GeoForschungsZentrum 2009 https://gfzpublic.gfz-potsdam.de/pubman/item/item_239307 unknown info:eu-repo/semantics/altIdentifier/doi/10.1007/s00024-009-0499-9 https://gfzpublic.gfz-potsdam.de/pubman/item/item_239307 Pure and Applied Geophysics 550 - Earth sciences info:eu-repo/semantics/article 2009 ftgfzpotsdam https://doi.org/10.1007/s00024-009-0499-9 2022-09-14T05:55:22Z Repeated gravity measurements were carried out from 1991 until 1999 at sites SE of Vatnajökull, Iceland, to estimate the mass flow and deformation accompanying the shrinking of the ice cap. Published GPS data show an uplift of about 13 ± 5 mm/a near the ice margin. A gravity decrease of –2 ± 1 μGal/a relative to the Höfn base station, was observed for the same sites. Control measurements at the Höfn station showed a gravity decrease of –2 ± 0.5 µGal/a relative to the station RVIK 5473 at Reykjavík (about 250 km from Höfn). This is compatible, as a Bouguer effect, with a 10 ± 3 mm/a uplift rate of the IGS point at Höfn and an uplift rate of ~20 mm/a near the ice margin. Although the derived gravity change rates at individual sites have large uncertainties, the ensemble of the rates varies systematically and significantly with distance from the ice. The relationship between gravity and elevation changes and the shrinking ice mass is modelled as response to the loading history. The GPS data can be explained by 1-D modelling (i.e., an earth model with a 15-km thick elastic lithosphere and a 7·10^17 Pa·s asthenosphere viscosity), but not the gravity data. Based on 2-D modelling, the gravity data favour a low-viscosity plume in the form of a cylinder of 80 km radius and 10^17 to 10^18 Pa·s viscosity below a 6 km-thick elastic lid, embedded in a layered PREM-type earth, although the elevation data are less well explained by this model. Strain-porosity-hydrology effects are likely to enhance the magnitude of the gravity changes, but need verification by drilling. More accurate data may resolve the discrepancies or suggest improved models. Article in Journal/Newspaper Ice cap Iceland Reykjavík Reykjavík Vatnajökull GFZpublic (German Research Centre for Geosciences, Helmholtz-Zentrum Potsdam) Reykjavík Vatnajökull ENVELOPE(-16.823,-16.823,64.420,64.420) Höfn ENVELOPE(-22.500,-22.500,65.433,65.433) Pure and Applied Geophysics 166 8-9 1283 1302 |
institution |
Open Polar |
collection |
GFZpublic (German Research Centre for Geosciences, Helmholtz-Zentrum Potsdam) |
op_collection_id |
ftgfzpotsdam |
language |
unknown |
topic |
550 - Earth sciences |
spellingShingle |
550 - Earth sciences Jacoby, W. Hartmann, O. Wallner, H. Smilde, P. Bürger, S. Sjöberg, L. Erlingsson, S. Wolf, D. Klemann, V. Sasgen, I. Temporal Gravity Variations near Shrinking Vatnajökull Ice Cap, Iceland |
topic_facet |
550 - Earth sciences |
description |
Repeated gravity measurements were carried out from 1991 until 1999 at sites SE of Vatnajökull, Iceland, to estimate the mass flow and deformation accompanying the shrinking of the ice cap. Published GPS data show an uplift of about 13 ± 5 mm/a near the ice margin. A gravity decrease of –2 ± 1 μGal/a relative to the Höfn base station, was observed for the same sites. Control measurements at the Höfn station showed a gravity decrease of –2 ± 0.5 µGal/a relative to the station RVIK 5473 at Reykjavík (about 250 km from Höfn). This is compatible, as a Bouguer effect, with a 10 ± 3 mm/a uplift rate of the IGS point at Höfn and an uplift rate of ~20 mm/a near the ice margin. Although the derived gravity change rates at individual sites have large uncertainties, the ensemble of the rates varies systematically and significantly with distance from the ice. The relationship between gravity and elevation changes and the shrinking ice mass is modelled as response to the loading history. The GPS data can be explained by 1-D modelling (i.e., an earth model with a 15-km thick elastic lithosphere and a 7·10^17 Pa·s asthenosphere viscosity), but not the gravity data. Based on 2-D modelling, the gravity data favour a low-viscosity plume in the form of a cylinder of 80 km radius and 10^17 to 10^18 Pa·s viscosity below a 6 km-thick elastic lid, embedded in a layered PREM-type earth, although the elevation data are less well explained by this model. Strain-porosity-hydrology effects are likely to enhance the magnitude of the gravity changes, but need verification by drilling. More accurate data may resolve the discrepancies or suggest improved models. |
author2 |
1.3 Earth System Modelling, 1.0 Geodesy and Remote Sensing, Departments, GFZ Publication Database, Deutsches GeoForschungsZentrum |
format |
Article in Journal/Newspaper |
author |
Jacoby, W. Hartmann, O. Wallner, H. Smilde, P. Bürger, S. Sjöberg, L. Erlingsson, S. Wolf, D. Klemann, V. Sasgen, I. |
author_facet |
Jacoby, W. Hartmann, O. Wallner, H. Smilde, P. Bürger, S. Sjöberg, L. Erlingsson, S. Wolf, D. Klemann, V. Sasgen, I. |
author_sort |
Jacoby, W. |
title |
Temporal Gravity Variations near Shrinking Vatnajökull Ice Cap, Iceland |
title_short |
Temporal Gravity Variations near Shrinking Vatnajökull Ice Cap, Iceland |
title_full |
Temporal Gravity Variations near Shrinking Vatnajökull Ice Cap, Iceland |
title_fullStr |
Temporal Gravity Variations near Shrinking Vatnajökull Ice Cap, Iceland |
title_full_unstemmed |
Temporal Gravity Variations near Shrinking Vatnajökull Ice Cap, Iceland |
title_sort |
temporal gravity variations near shrinking vatnajökull ice cap, iceland |
publishDate |
2009 |
url |
https://gfzpublic.gfz-potsdam.de/pubman/item/item_239307 |
long_lat |
ENVELOPE(-16.823,-16.823,64.420,64.420) ENVELOPE(-22.500,-22.500,65.433,65.433) |
geographic |
Reykjavík Vatnajökull Höfn |
geographic_facet |
Reykjavík Vatnajökull Höfn |
genre |
Ice cap Iceland Reykjavík Reykjavík Vatnajökull |
genre_facet |
Ice cap Iceland Reykjavík Reykjavík Vatnajökull |
op_source |
Pure and Applied Geophysics |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1007/s00024-009-0499-9 https://gfzpublic.gfz-potsdam.de/pubman/item/item_239307 |
op_doi |
https://doi.org/10.1007/s00024-009-0499-9 |
container_title |
Pure and Applied Geophysics |
container_volume |
166 |
container_issue |
8-9 |
container_start_page |
1283 |
op_container_end_page |
1302 |
_version_ |
1766028477606133760 |