Iceland volcano: and you thought the last eruption was bad…

Large eruptions such as this occur only every few hundred years on Iceland,
but the potential for danger is significant. Even if deaths from famine are
less likely today, a recent study of the potential effects of the air
pollution caused by such an eruption estimates that it could lead to between
52,000 and 228,000 fatalities throughout Europe.

Meanwhile, nearby Hekla has erupted about once every 10 years in recent times,
with the last being in 2000. Similarly, volcanoes beneath the largest ice
cap, Vatnajökull, are entering a period of increased volcanic activity – the
peak of a 140‑year cycle.

This trend is being exacerbated by climate change. Vatnajökull has lost an
estimated 400  billion tonnes of ice since the end of the 19th century. This
has reduced the pressure on the hot mantle material beneath the crust,
leading to increased magma generation. At the end of the last ice age, this
same effect led to eruption rates some 30 times higher than at present. The
current rate of ice loss is much lower than then, but we can still expect
the formation of extra magma equivalent to that which erupted from
Eyjafjallajökull in 2010 every 10 years or so.

There is a question mark over whether and when all this extra magma will
erupt, however. Studies indicate that the timelag between generation and
eruption could be as much as a few hundred years. In the meantime, the
shrinking of the ice cap also causes stress changes in the crust that can
encourage, or discourage, capture of the magma on its way up, depending on
the path it takes.

The scale of the chaos that an eruption could cause is difficult to estimate.
Partly it would depend on which way the winds are blowing but also on the
style, size and duration of the eruption. Perhaps surprisingly, the
magnitude is less important than the type of eruption.

While the Eyjafjallajökull eruption was relatively small, it caused such havoc
because the materials ejected had the perfect make-up to ground flights:
fine ash was deposited high enough to remain airborne for days, affecting
the airspace of continental Europe. An eruption of Katla is likely to have a
similar explosive style, due to the interaction of the magma and the
overlying ice cap – the heat of the magma causes the transformation of ice
to steam, which expands and fragments the magma.

A key goal for scientists
and aviation authorities must be to develop predictive capability as to the
nature of forthcoming eruptions. We would then be able to construct better
plans for dealing with the impact, including the threat to agriculture and
air travel.

To this end, my group at Delft University of Technology is working with the
University of Iceland and others to develop more accurate models of volcanic
plumbing systems. Using GPS receivers, satellite-borne radar, and advanced
algorithms, we have been able to track the movement of magma and create maps
of magma storage.

Just as importantly, the risks associated with the largest Icelandic
eruptions, such as that which occurred in 1783-84, need to be thoroughly
assessed. Even though these events occur only every few hundred years, the
potential for widespread loss of life means we need to be properly prepared.

As we face continuing volcanic activity in Iceland and across the world, it is
vital we improve the science of eruption prediction and so guard against the
worst consequences.

Dr Andy Hooper is an assistant professor at Delft University of Technology

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