The Eyjafjallajökull volcanic system, Iceland: insights from electromagnetic measurements
Marion P. Miensopust, Alan G. Jones, Gylfi Páll Hersir and Arnar M. Vilhjálmsson
Electromagnetic measurements were performed one year after the most recent eruption of the Eyjafjallajökull volcano (March -May 2010),
southern Iceland, to investigate the geometries of structures of the volcano system through imaging lateral and vertical electrical resistivity
High quality magnetotelluric and transient electromagnetic data were acquired at 26 sites around Eyjafjallajökull and the southern part
of Mýrdalsjökull (the glacier covering the Katla volcano).
For some locations the steep topography has influence on the magnetotelluric responses, but this can be compensated by
static shift correction using the transient electromagnetic data and/or including topography in the modelling mesh.
As expected, qualitative indicators, such as phase tensor ellipses and induction arrows, infer a concentration of conductive
material beneath Eyjafjallajökull.
Two-dimensional resistivity models are presented from data along three profiles: Along the river valley of Markarfljót in the north,
along the coast to the south of Eyjafjallajökull and across the mountain ridge Fimmvörðuháls between Eyjafjallajökull and Katla.
In numerous previous studies elsewhere in Iceland a conductive layer at about 10 - 30 km depth was identified.
From our data, such a conductor is also present in the north eastern part of the investigated area.
Additionally, all profiles show a conductive, near-surface layer at about 1 - 2 km depth, as seen previously for example
at the Hengill geothermal region.
A connection between those two conductive layers is indicated by the resistivity models, and the dyke (flank eruption) and the
conduit (summit eruption) appear as vertical conductive structures.
It is uncertain if the vertical connection is permanent or a transient feature as consequence of the eruptive sequences.
Subsequent measurements are required when the volcano system is quiescent.
Geophysical Journal International, 199, 1187-1204, doi: 10.1093/gji/ggu322. [PDF]
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Alan G Jones / 29 September 2014 /