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Update on activity Grímsvötn


Grímsvötn volcano
Status Report: 16:00 GMT, 26 May 2011
Icelandic Meteorological Office and Institute of Earth Sciences, University of Iceland
Compiled by:
Sigurlaug Gunnlaugsdóttir, Gunnar B. Guðmundsson and Björn
Oddsson, with input from Gunnar Sigurðsson, Þórður Arason, Matthew
J. Roberts, Sigrún Hreinsdóttir and Sibylle von Löwis.
Based on:
IMO seismic monitoring; IES-IMO GPS monitoring; IMO
hydrological data; weather radar; ash-fall reports; scientific overflights;
UK Met Office ATDnet; MODIS and NOAA satellite images.
Eruption plume:
Height (a.s.l.):
Plume not detected on radar at 70 km distance from the eruption site..
Minor steam explosion observed in the crater.
Heading:
--
Colour:

--
Tephra fallout:
Only in the vicinity of the eruption site.
Lightning:
No lightning strikes detected.
Noise:
No noise.
Meltwater:
Visual observations of Grímsvötn show that little ice has melted during
the eruption, meaning that an outburst flood (jökulhlaup) is not to be
expected. Long-term conductivity measurements of Gígjukvísl suggest
that meltwater is draining freely from Grímsvötn following a
jökulhlaup from the lake last autumn.
Conditions at eruption site:
Ongoing gas-explosions in a crater towards the south in the volcano,
according to an overflight yesterday at 19 hrs.
Seismic tremor:
Seismic tremor at similar levels since yesterday but fluctuates
frequently. Tremor bursts recorded at seismic stations up to 200 km
distance from the volcano.

Earthquakes:
No earthquakes were recorded in the volcano.
GPS deformation:
No significant displacement observed at the GPS-station at Mt.
Grimsfjall yesterday.

Overall assessment: Very little changes since yesterday. Explosions continue, only affecting
the area around the crater.

Details in status report issued collectively by the Icelandic Meteorological Office and the Institute of Earth Sciences