The recognition of geophysical precursors
to volcanic activity is a primary challenge
in volcano monitoring. That challenge was
successfully met by scientists at the Icelandic
Meteorological Offi ce (IMO) before the
1 November 2004 eruption of Grímsvötn, a
subglacial volcano beneath the Vatnajökull
ice cap, Iceland (Figure
1).
Seismic and geodetic precursors were prop-
erly recognized
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