Reykjavík Grapevine - 29.08.2014, Blaðsíða 12

12
The Reykjavík Grapevine
Issue 13 — 2014
The situation at Bárðarbunga is quite
complex and, as such, presents a range of
possibilities. Most of these possibilities
are exciting; some of them are dangerous;
none of them are terrifying. Let’s take a
look at the first possibility: there is no
eruption. Yep, that’s right—it might not
even happen! As I write this, the magma
is currently making its way towards the
surface in what we call a dike (stop snig-
gering, you at the back)—rather than
coming straight up, the magma is follow-
ing a line of weakness in the crust some
35 or so kilometres long (and growing!).
Prior to the 2010 Eyjafjallajökull erup-
tion, there were several ‘false starts’ in
previous years, where dikes just petered
out before they hit the surface. There’s
nothing to say that couldn’t happen here.
The second possibility is that we see
something like the first part of the 2010
eruption. As the magma ascends, it ap-
pears to be moving slowly northwards,
away from Vatnajökull. If the dike were
to reach the surface away from thick ice
cover, it could result in a spectacular fire-
fountaining eruption similar to the one
that drew so many tourists in 2010. This
probably wouldn’t produce much ash, so
risks to aviation would be small, and it
would be unlikely to have effects much
beyond the immediate area. Marshmal-
lows, anyone?
Another possibility has the potential
to be somewhat more troublesome, al-
though it’s appearing somewhat less like-
ly as time goes on. If there is an eruption
beneath the ice, the hot magma coming
into contact with cold meltwater could
trigger production of an ash cloud. The
eruption at Eyjafjallajökull was excep-
tional for several reasons—the second
stage occurred both beneath the glacier
and was of a different, thicker, more gas-
rich magma type than the first. Both of
these combined created a situation in
which the ash produced was very fine
indeed, leading to it being carried a long
way into the atmosphere. Unlucky for
travellers, but a repeat performance is
not guaranteed, even in the case of an-
other sub-glacial eruption. Arguably the
biggest threat from a sub glacial eruption
is that of a jökulhlaup—a glacier outburst
flood—but authorities will be ready to
evacuate anyone at risk (locals only!)
from the area if there is any chance of
that.
The final possibility of note is a par-
ticularly interesting one, deserving of a
whole article on its own (and a whole lot
more research on my part!). The dike is
actually headed in the direction of the
really rather large Askja volcano. We
know there is magma built up beneath
the Askja caldera, so if this dike were to
hit that, it could trigger something much
larger than we could otherwise see.
However, saying much beyond that right
now would be speculation, bordering on
scaremongering, so I will refrain...
In summary: don’t worry about it.
Many different things could happen, only
a couple of them present any cause for
concern, and they are unlikely to affect
you anyway. Volcanoes are fickle beasts,
incredibly hard to predict, and The Daily
Mail are going to do a worse job of that
than the scientists on the ground. Leave
it to the volcanologists—we know what
we’re doing. Mostly.
Bárðarbunga: it’s going to explode, you’re going to be
trapped in Iceland for six months and you might die a hor-
rific, fiery death. Why? Because such grand claims make
good headlines and sell papers, that’s why. Personally, I’ve
always believed more in science than sensationalism, so if
you’ll permit me, I’d love to spread a little of that...
What Will
Become Of
Bárðarbunga?
A man of science
explores the options
Words by James Ashworth
Photo by Axel Sigurðarson
News | Media events
Our wonderful photographer friend Axel Sigurðarson spent
the weekend of the non-eruption eruption flying over the
alleged area of geological unrest. See more of those shots at
www.grapevine.is