Geodetic GPS measurements in south Iceland

Strain accumulation and partitioning in a propagating ridge system

Peter Christopher Lafemina, T. H. Dixon, R. Malservisi, T. Árnadóttir, E. Sturkell, F. Sigmundsson, P. Einarsson

Research output: Contribution to journalArticle

84 Citations (Scopus)

Abstract

GPS observations in south Iceland between 1994 and 2003 are compared with two-dimensional elastic half-space and viscoelastic coupling models for two parallel rift zones, representing the Western and Eastern volcanic zones (WVZ, EVZ). GPS data from the Hreppar block, between the WVZ and EVZ, fit a rigid block model within uncertainties. Spreading rates across the WVZ increase from 2.6 ± 0.9 mm/yr in the northeast to 7.0 ± 0.4 mm/yr in the southwest. Conversely, spreading rates in the EVZ decrease from 19.0 ± 2.0 mm/yr in the northeast to 11.0 ± 0.8 mm/yr in the southwest, the direction of ridge propagation. Summed extension rates across the two rift zones are approximately constant and equal to the total plate rate, ∼18-20 mm /yr, consistent with a simple propagating ridge model whereby the WVZ is deactivating in the direction of EVZ propagation. The coupling model confirms results from the simple elastic half-space model, including relatively shallow locking depths (<5 km) beneath the rift zones, and allows for an estimate of mean viscosity (∼1019-1020 Pa s) beneath the elastic layer. The location of maximum surface velocity gradient in the EVZ, presumably the locus of subsurface magma accumulation and future rifting, does not coincide with the 1783-1784 Lakagígar fissure eruption but is 20 km to the west, on the Bároabunga-Veidivötn fissure swarm. This had a small volume eruption in 1862-1864 but a major eruption in 1477 A.D.

Original languageEnglish (US)
Article numberB11405
Pages (from-to)1-21
Number of pages21
JournalJournal of Geophysical Research: Solid Earth
Volume110
Issue number11
DOIs
StatePublished - Nov 4 2005

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Iceland
Global positioning system
ridges
GPS
partitioning
rift zone
volcanic eruptions
volcanic eruption
half space
half spaces
fissure
propagation
loci
magma
locking
rifting
volcanology
viscosity
Viscosity
gradients

All Science Journal Classification (ASJC) codes

  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Atmospheric Science
  • Astronomy and Astrophysics
  • Oceanography

Cite this

Lafemina, Peter Christopher ; Dixon, T. H. ; Malservisi, R. ; Árnadóttir, T. ; Sturkell, E. ; Sigmundsson, F. ; Einarsson, P. / Geodetic GPS measurements in south Iceland : Strain accumulation and partitioning in a propagating ridge system. In: Journal of Geophysical Research: Solid Earth. 2005 ; Vol. 110, No. 11. pp. 1-21.
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Lafemina, PC, Dixon, TH, Malservisi, R, Árnadóttir, T, Sturkell, E, Sigmundsson, F & Einarsson, P 2005, 'Geodetic GPS measurements in south Iceland: Strain accumulation and partitioning in a propagating ridge system', Journal of Geophysical Research: Solid Earth, vol. 110, no. 11, B11405, pp. 1-21. https://doi.org/10.1029/2005JB003675

Geodetic GPS measurements in south Iceland : Strain accumulation and partitioning in a propagating ridge system. / Lafemina, Peter Christopher; Dixon, T. H.; Malservisi, R.; Árnadóttir, T.; Sturkell, E.; Sigmundsson, F.; Einarsson, P.

In: Journal of Geophysical Research: Solid Earth, Vol. 110, No. 11, B11405, 04.11.2005, p. 1-21.

Research output: Contribution to journalArticle

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T2 - Strain accumulation and partitioning in a propagating ridge system

AU - Lafemina, Peter Christopher

AU - Dixon, T. H.

AU - Malservisi, R.

AU - Árnadóttir, T.

AU - Sturkell, E.

AU - Sigmundsson, F.

AU - Einarsson, P.

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N2 - GPS observations in south Iceland between 1994 and 2003 are compared with two-dimensional elastic half-space and viscoelastic coupling models for two parallel rift zones, representing the Western and Eastern volcanic zones (WVZ, EVZ). GPS data from the Hreppar block, between the WVZ and EVZ, fit a rigid block model within uncertainties. Spreading rates across the WVZ increase from 2.6 ± 0.9 mm/yr in the northeast to 7.0 ± 0.4 mm/yr in the southwest. Conversely, spreading rates in the EVZ decrease from 19.0 ± 2.0 mm/yr in the northeast to 11.0 ± 0.8 mm/yr in the southwest, the direction of ridge propagation. Summed extension rates across the two rift zones are approximately constant and equal to the total plate rate, ∼18-20 mm /yr, consistent with a simple propagating ridge model whereby the WVZ is deactivating in the direction of EVZ propagation. The coupling model confirms results from the simple elastic half-space model, including relatively shallow locking depths (<5 km) beneath the rift zones, and allows for an estimate of mean viscosity (∼1019-1020 Pa s) beneath the elastic layer. The location of maximum surface velocity gradient in the EVZ, presumably the locus of subsurface magma accumulation and future rifting, does not coincide with the 1783-1784 Lakagígar fissure eruption but is 20 km to the west, on the Bároabunga-Veidivötn fissure swarm. This had a small volume eruption in 1862-1864 but a major eruption in 1477 A.D.

AB - GPS observations in south Iceland between 1994 and 2003 are compared with two-dimensional elastic half-space and viscoelastic coupling models for two parallel rift zones, representing the Western and Eastern volcanic zones (WVZ, EVZ). GPS data from the Hreppar block, between the WVZ and EVZ, fit a rigid block model within uncertainties. Spreading rates across the WVZ increase from 2.6 ± 0.9 mm/yr in the northeast to 7.0 ± 0.4 mm/yr in the southwest. Conversely, spreading rates in the EVZ decrease from 19.0 ± 2.0 mm/yr in the northeast to 11.0 ± 0.8 mm/yr in the southwest, the direction of ridge propagation. Summed extension rates across the two rift zones are approximately constant and equal to the total plate rate, ∼18-20 mm /yr, consistent with a simple propagating ridge model whereby the WVZ is deactivating in the direction of EVZ propagation. The coupling model confirms results from the simple elastic half-space model, including relatively shallow locking depths (<5 km) beneath the rift zones, and allows for an estimate of mean viscosity (∼1019-1020 Pa s) beneath the elastic layer. The location of maximum surface velocity gradient in the EVZ, presumably the locus of subsurface magma accumulation and future rifting, does not coincide with the 1783-1784 Lakagígar fissure eruption but is 20 km to the west, on the Bároabunga-Veidivötn fissure swarm. This had a small volume eruption in 1862-1864 but a major eruption in 1477 A.D.

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