Reykjavík Grapevine - 16.06.2016, Side 60

On the southern Ring Road, near
Skógafoss, sits the curious site
of Rútshellir—a man-made cave
carved into a huge chunk of rock.
During the early 20th century
a stone barn was built onto the
entrance, making it look like a
ruined house, but the cave itself
dates back much farther. There’s
evidence inside that it was used as
a forge at some point, and before
that, a residence. And, this being
Iceland, there’s a legend attached
to it. The story goes that the cave
was once inhabited by Rútur—an
evil looter, or a troll (depending on
which version you’re hearing) who
kept slaves. Three of his slaves,
Sebbi, Högni and Guðni, attempt-
ed to murder Rútur with a spear.
They failed, and he chased them
down, killing all three. Guðni ap-
parently got farthest—he made it
all the way to the top of Eyjafjal-
lajökull before being slain, and
Guðnasteinn (“Guðni's Rock”)
marks where he died. But the story
of Rútshellir doesn’t end there—
in 1936, a wing of Himmler’s SS,
charged with investigating Nordic
history, surveyed the cave sus-
pecting it might be the site of a ru-
ined temple. And finally, last year,
the landowner rebuilt the barn
structure with a wooden roof, to
stop it from collapsing. Rútshellir
is listed as a heritage site, and is
open to the public.
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On The Road:
Rútshellir
Words JOHN ROGERS Photo ART BICNICK
60 The Reykjavík GrapevineIssue 8 — 2016TRAVEL
“No one can predict where, or with what
force, an eruption might commence.”
Slumbering
Volcanoes
Words ARI TRAUSTI
Photos CLÉMENCE FLORIS, ANNA ANDERSEN
Currently, some of the 30 volcanic
systems in Iceland, most of them
with a large central volcano, show
signs of unrest. It is ever thus, but
a greater or lesser number of dor-
mant volcanoes are potentially
active in any given decade or so.
In some cases, as with Hekla and
Grímsvötn, monitoring tells us
that swelling of the volcano, and
of the nearby crust (due to an influx
of magma), has reached the same
threshold as before the volcano’s
last eruption. This, however, is not
enough to permit a sound forecast.
In the subglacial Katla central
volcano, frequent earthquakes
(some at a depth of 15-25 km), in-
creased geothermal activity and
crustal uplift are telltale signs of
something brewing. This swell-
ing, however, is partly due to a
lessening ice load and partly due
to an influx of magma.
Currently, the glacier-covered
Bárðarbunga central volcano also
receives some magma, but it is im-
possible to predict what threshold
the increased magma pressure
and growing tensile stresses must
attain before fissures in the crust
become filled with magma (dyke
formation, in geological terms)
and, eventually, a volcanic erup-
tion starts. Nor can anyone pre-
dict where or with what force such
an eruption might commence. An
eruption in Bárðabunga proper
means interaction between mag-
ma and ice, producing ash and
pumice plus a large and powerful
flash flood. A more distant erup-
tion within the vast, elongated
Bárðarbunga volcanic system, and
in an ice-free area, would mean
a lava-producing event in the
fashion of the well-documented
Holuhraun event. That lasted six
months, basically from the end of
August 2014 to the end of February
2015, forming a lava flow with an area
of almost 90 square kilometres.
Not over, yet
Lessons from former episodes of
unrest in the large Bárðarbunga
volcanic system are clear. Most
episodes, with rifting and volcanic
activity, tend to stretch over many
years, even decades. Some of the
rifting and eruption events during
each episode have been powerful
and productive, with a lot of ash
and lava pouring out from fissures
in ice-free areas, as for example in
the late 15th century (the Veiðivötn
Fires).
Elaborate monitoring now re-
veals that the central region of
the volcanic system, including
the Bárðarbunga central volcano
with its ice-covered caldera, has
not come to a rest. Magma rises
into the deep plumbing system
below the volcano. This is evident
from GPS monitoring stations.
A recent data interpretation map
from the Icelandic Met Office and
the University of Iceland shows
horizontal movements that are a
combination of general tectonic
plate drift, and swelling due to
magma rising from depth. A GPS
station high up on the flanks of
Bárðarbunga moved over 6.5 cm to
the northwest between July 10th
and mid-December 2015, and si-
multaneously rose some 3 cm in
altitude. Earthquakes are being
registered in abundance and quite
many have attained magnitudes
between 3.0 and 3.8 on the Richter
Scale.
It remains to be seen what all of
this will bring us in the near fu-
ture. A renewed period of rifting
within the Bárðarbunga system,
possibly including a volcanic erup-
tion, can start any time. The moni-
toring system is, however, capable
of delivering a warning, hours or
days prior to such an event.
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