Detecting magma bodies in the Icelandic crust: Constraints from Volcano Geodesy and Joint Interpretation with Other Data
Abstract
Detailed geodetic observations have been carried on a number of volcanoes in Iceland, including both GPS-measurements and interferometric analysis of synthetic aperture radar images acquired by satellites (InSAR), with observed surface deformation interpreted in terms of magmatic processes. Volcanoes where data has been interpreted in terms of persistent magma reservoirs (magma storage areas) include Krafla, Askja, Bárdarbunga, Grímsvötn, Hekla, Katla and Eyjafjallajökull volcanoes. Magma storage is inferred beneath the centers of these volcanoes, at depth ranging from 2-25 km, when deformation data is interpreted in terms of point sources of pressure (Mogi models), or alternatively as sills or spheroids. The lateral dimensions and volume of the sources are difficult to constrain from geodesy alone, but the geodetic data suggests though in all cases localized reservoirs under the center of the volcanoes (beneath calderas or maxima in volcanic production). In some cases, external constraints applied on geodetic models are crucial, such as for the study of 2014-2015 caldera collapse (>60 m), dyking and major eruption within the Bárðarbunga volcanic system 2014-2015. Geobarometry from petrology and geochemistry provides independent constraints on depth of a magma reservoir, and together all data suggest a depth range of 10-12 km. Volume extracted from the reservoir was about 2 cubickilometers. For the case of caldera collapse, incorporation of slip on caldera into geodetic models is required to properly address the data. Geodetic data relating to a magma reservoir under Bárðarbunga and other volcanoes in Iceland will be reviewed and compared to other constraints from petrology, geochemistry and seismology, with joint models of interpretation presented, considering possibilities and resolution of each type of data. At one volcano (Krafla) inferred models of subsurface magma plumbing can be compared to results from drilling into a rhyolitic magma body at 2.1 km depth below a geothermal area. Because of the direct confirmation of magma in the area, there are ongoing international efforts to create a "Krafla Magma Testbed (KMT)". In future, magma underground could be studied through international cooperation merging geothermal and volcanological research and technological development.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.V41E..02S
- Keywords:
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- 1036 Magma chamber processes;
- GEOCHEMISTRYDE: 1037 Magma genesis and partial melting;
- GEOCHEMISTRYDE: 8439 Physics and chemistry of magma bodies;
- VOLCANOLOGYDE: 8486 Field relationships;
- VOLCANOLOGY