Iceland review - 2015, Side 34

32 ICELAND REVIEW
During the course of the Holuhraun erup-
tion and in consistency with seismic events
in the volcano, the Bárðarbunga caldera has
subsided 70 meters, creating a depression
in the glacier. Gradually, pressure will start
building again, lifting the caldera, but when
that will happen is unknown. GPS data
indicates that the caldera is already rising
again, but that isn’t necessarily the result
of magma accumulating. “It’s the ice lifting,
sliding in from the sides—it’s adapting to
the changes,” Víðir states. Haraldur objects:
“Such a development would take years, not
days.” But he isn’t convinced that magma is
building up either. “It could be meltwater
flowing into the caldera, floating the ice,”
he suggests. Haraldur explains that even
though magma is building up, it would take
years or decades for another eruption to
occur in Bárðarbunga. “The magma flows
one hundred or thousand times faster out
than in.”
Ármann Höskuldsson, volcanologist at
the University of Iceland’s Earth Sciences
Institute, believes we’re looking at a rift-
ing episode and that Holuhraun is just
the beginning of a series of eruptions.
He points out that it’s similar in nature
to Kröflueldar, a series of volcanic events
in Krafla in Northeast Iceland, produc-
ing ten eruptions in the nine-year period
1975-1984. “In the history of Bárðarbunga,
we have examples of both, a single erup-
tion and then nothing for a long time,
and a series of eruptions over a few
years,” Kristín says. She points out that
as a large part of the volcanic system lies
under Vatnajökull, there’s a high risk of a
sub-glacial eruption. This could lead to
the dreaded worst-case scenario of mas-
sive ash fall disrupting air traffic, and cat-
astrophic flooding in glacial rivers, poten-
tially damaging not only farms and farm-
land but also hydropower plants. “We will
know with some notice, I hope. We have
collected valuable data and have learned a
whole lot by how these events developed.
For now it appears as if the system has
ERUPTION