Reykjavík Grapevine - 16.06.2016, Blaðsíða 60

Reykjavík Grapevine - 16.06.2016, Blaðsíða 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. SHARE: gpv.is/rut 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. SHARE: gpv.is/at8
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