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Gravity and elevation changes at Askja, Iceland

Rymer, Hazel and Tryggvason, Eysteinn (1993). Gravity and elevation changes at Askja, Iceland. Bulletin of Volcanology, 55(5) pp. 362–371.

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Ground tilt measurements demonstrate that Askja is in a state of unrest, and that in the period 1988 - 1991 a maximum 48 +/- 3 µrad tilt occurred down towards the centre of the caldera. This is consistent with 126 mm of deflation at the centre of the caldera with a 2.5 - 3.0 km depth to the source of deformation. The volume of the subsidence bowl is 6.2 x 106 m3. When combined with high precision microgravity measurements, the overall change in sub-surface mass may be quantified. After correction for the observed elevation change using the free air gradient of gravity measured for each station, the total change in mass is estimated to be less than 109 kg. A small residual ground inflation and net gravity increase in the eastern part of the caldera may be caused by dyke intrusion in this region. The minimum dimensions of such an intrusion or complex of intrusions are 1m width, up to 100m deep and up to several hundred metres thick.

Item Type: Journal Article
ISSN: 0258-8900
Extra Information: The original publication is available at
Keywords: volcanoes; intrusions;
Academic Unit/Department: Other Departments > Learning and Teaching
Other Departments
Interdisciplinary Research Centre: Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)
Item ID: 66
Depositing User: Users 12 not found.
Date Deposited: 30 May 2006
Last Modified: 05 Oct 2016 01:46
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