Bulletin of Volcanology

, Volume 68, Issue 7–8, pp 727–735

1983–2003 decaying rate of deflation at Askja caldera: Pressure decrease in an extensive magma plumbing system at a spreading plate boundary

  • Erik Sturkell
  • Freysteinn Sigmundsson
  • Ragnar Slunga
Research Article

Abstract

New deformation data from the Askja volcano, Iceland, show that the volcano's caldera has been deflating continuously for over 20 years, and confirm that the rate of subsidence is slowing down. The decay in subsidence rate can be fitted with a function of the form et/τ, where τ is 39 years. Reanalysis of GPS data from 1993–1998 show that these data can be fitted with a model calling for two Mogi point sources, one shallow, and another one much deeper (16.2 km depth). Pressure decrease occurs in both sources. The deeper source is responsible for observed horizontal contraction towards Askja at distances that cannot be explained by the shallower source. Plate spreading of 19 mm/year distributed evenly over about 100-km-wide zone is also favoured by the data.

Keywords

Caldera Volcano deformation GPS Plate boundary 

References

  1. Bevington PR (1969) Data reduction and error analysis. McGraw-Hill, New YorkGoogle Scholar
  2. Camitz J, Sigmundsson F, Foulger G, Jahn C-H, Voelksen C, Einarsson P (1995) Plate boundary deformation and continuing deflation of the Askja volcano, North Iceland, determined with GPS, 1987–1993. Bull Volcanol 57:136–145ADSGoogle Scholar
  3. Delaney PT, McTigue DF (1994) Volume of magma accumulation and withdrawal estimated from surface uplift or subsidence, with application to the 1960 collapse of Kilauea volcano. Bull Volcanol 56:417–424CrossRefADSGoogle Scholar
  4. DeMets C, Gordon RG, Argus DF, Stein S (1994) Effect of recent revision to the geomagnetic reversal time scale on estimates of current plate motions. Geophys Res Lett 21:2191–2194CrossRefADSGoogle Scholar
  5. Heki K, Foulger GR, Julian BR, Jahn C-H (1993) Plate dynamics near divergent boundaries: Geophysical implications of postrifting crustal deformation in NE Iceland. J Geophys Res 98:14279–14297ADSCrossRefGoogle Scholar
  6. Johnson DJ, Sigmundsson F, Delaney PT (2000) Comment on “Volume of magma accumulation or withdrawal estimated from surface uplift or subsidence, with application to the 1960 collapse of Kilauea volcano” by Delaney PT and McTigue DF. Bull Volcanol 61:491–493CrossRefADSGoogle Scholar
  7. La Femina PC, Dixon TH, Malservisi R, Árnadóttir T, Sturkell E, Sigmundsson F, Einarsson P (2004) Geodetic GPS measurements in South Iceland: strain accumulation and partitioning in a propagating ridge system. J Geophys Res Vol. 110, No. B11,B11405, doi:10.1029/2005JB003675Google Scholar
  8. Mogi K (1958) Relations between the eruptions of various volcanoes and the deformation of the ground surface around them. Bull Earthq Res Inst 36:99–134Google Scholar
  9. Pagli C, Sigmundsson F, Arnadottir T, Einarsson P, Sturkell E (2006) Deflation of the Askja volcanic system: constraints on the deformation source from combined inversion of satellite radar interferometry and GPS measurements. J Volcanol Geotherm Res doi:10.1016/j.jvolgeores.2005.09.014 (in press)Google Scholar
  10. Rymer H, Tryggvason E (1993) Gravity and elevation changes at Askja, Iceland. Bull Volcanol 55:362–371CrossRefADSGoogle Scholar
  11. Sigvaldason GE (1979) Rifting, magmatic activity and interaction between acid and basic liquids. The 1875 Askja eruption in Iceland. Nordic Volcanological Institute (report) 7903, pp 1–54Google Scholar
  12. Sturkell E, Sigmundsson F (2000) Continuous deflation of the Askja Caldera, Iceland during the 1983–1998 non-eruptive period. J Geophys Res 105:25671–25684CrossRefADSGoogle Scholar
  13. Thorarinsson S (1968) On the rate of lava and tephra production and the upward migration of magma in four Icelandic eruptions. Geol Rundsch 57:705–718CrossRefADSGoogle Scholar
  14. Tryggvason E (1986) Multiple magma reservoirs in a rift zone volcano: Ground deformation and magma transport during the September 1984 eruption of Krafla, Iceland. J Volcanol Geotherm Res 28:1–44CrossRefADSGoogle Scholar
  15. Tryggvason E (1989) Ground deformation in Askja, Iceland: Its source and possible relation to flow of the mantle plume. J Volcanol Geotherm Res 39:61–71CrossRefADSGoogle Scholar
  16. de Zeeuw-van Dalfsen E, Rymer H, Sigmundsson F, Sturkell E (2004) Net gravity decrease at Askja volcano, Iceland: Constraints on processes responsible for continuous caldera deflation, 1988–2003. J Volcanol Geotherm Res 139/3-4:227–239 doi:10.1016/j.jvolgeores.2004.08.008ADSGoogle Scholar
  17. de Zeeuw-van Dalfsen E, Rymer H, Williams-Jones G, Sturkell E, Sigmundsson F (2006) The integration of micro-gravity and geodetic data at Krafla Volcano, N Iceland. Bull Volcanol doi:10.1007/s445-005-0018-5 (in press) Google Scholar

Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • Erik Sturkell
    • 1
    • 2
  • Freysteinn Sigmundsson
    • 2
  • Ragnar Slunga
    • 3
  1. 1.Icelandic Meteorological OfficeReykjavikReykjavik Iceland
  2. 2.Nordic Volcanological CenterInstitute of Earth Sciences, University of IcelandReykjavikReykjavik Iceland
  3. 3.University of UppsalaUppsalaSweden

Personalised recommendations