Grimsvotn: Iceland’s Most Active Volcano Wakes With a Roar
Grimsvotn, Iceland’s most active volcano, is up to its old tricks but unlike the ashy eruption of Eyjafjallajökull in 2010, air traffic is not expected to be affected. This will make it easier for photographers to travel to Iceland, where they can add to their already considerable portfolio of spectacularly smokey images of one of Earth’s most awe-inspiring geological events.
Land of Ice and Fire
Iceland is home to approximately 130 volcanoes, which over the past 500 years have pumped out about one third of the total global output of lava. Not bad for a country slightly smaller than Kentucky and about half the size of Great Britain… well, actually it IS bad, especially if you live there.
Since settlers first arrived in Iceland back in 874 AD, these hardy Vikings and their descendants have had to endure repeated and regular eruptions from 18 different volcanoes. Arguably the worst of these began in 1783 and continued for roughly 8 months; the so-called Skaftáreldar (fires of Skaftá) event centered on the Lakagígar (craters of Laki) in central Iceland.
It’s estimated that up to a quarter of Iceland’s population (and up to 6 million worldwide!) died from direct and indirect effects of the eruption and thousands more perished in Europe, which was subsumed by noxious clouds of ash and acidic vapor for months on end. Weather patterns around the globe were disrupted leading to crop failures, water shortages and famine as far away as Japan.
(image via: Vulkaner.no)
Rated by the total volume (an estimated 14 km3 or 3.4 cubic miles) of lava expelled, the eruption of Laki tops the list of the largest single volcanic eruptions in historic times. Ominously, the central volcano in the Laki group is Grimsvotn. Though the Laki craters appear lush with verdant vegetation today, one never can tell if the area will erupt again in the future. Grimsvotn, on the other hand, is very predictable due to the frequency of its eruptions.
What Lies Beneath
Grimsvotn erupted in 1922, 1933, 1934, 1938, 1945, 1954, 1983, 1998 and most recently in 2004… and those were just the MAJOR eruptions. The current phase is reckoned to be the most powerful since 1873. here’s a video of the 2011 eruption on its first day, taken from the air:
You’d think with so many eruptions, Grimsvotn would have built up a typical cone-shaped volcano profile by now but Grimsvotn, like many of Iceland’s volcanoes, is anything but typical.
Thanks to its far-northern latitude, Iceland really is an “icy land” – I guess Erik the Red could only get away with that “Green Land” shtick once. It’s also one of the most volcanic places on the planet, and one of the only places where a mid-ocean ridge is diverging above sea level.
(image via: Tushar Gupta)
This constant “pulling apart” results in a series of rift valleys being formed from which most of Iceland’s volcanic eruptions occur. Contrast this with volcanic zones in Japan, the South American Andes and along North America’s west coast where one tectonic plate is subducting beneath another, producing familiar volcanic cones and peaks.
(images via: Matthew J. Roberts, Global Volcanism Program)
Grimsvotn enjoys a double-whammy of being located in a rift valley that itself is covered by Iceland’s largest glacier: Vatnajökull. Can you imagine what happens when an erupting volcano meets a glacier? Here’s a hint – the volcano wins. Though blanketed by ice 150 to 200 m (490 to 655 ft) thick, it only took about an hour for Grimsvotn’s eruption to melt its way to the surface.
(images via: Icelandic Met Office)
Icelanders have learned to note certain signs that indicate Grimsvotn is heating up. Chief among them is the Jökulhlaup (glacial outburst flood) that emerges from the edge of the Skeiðarárjökull outlet glacier. The images above show the Jökulhlaup of October 2010. While in this instance the flood wasn’t immediately followed by an eruption, it broadly hinted at the one to come some 7 months later.
Computing the Cloud
(image via: Xinhuanet)
With the 2010 Eyjafjallajokull eruption’s widespread disruption of air traffic still in the minds of air travelers and airlines, word that Grimsvotn had erupted violently on May 21sst of 2011 immediately sparked worry that a similar situation would occur. Photos of Grimsvotn’s towering ash cloud – estimated to have reached a height of 20 km (12 miles) – graphically illustrated these fears.
(images via: Daily Mail UK)
Though the world may be thinking global, Grimsvotn acts local. According to Open University Volcano Dynamics Group expert David Rothery, “There is no reason to expect Grimsvotn’s current eruption to produce the volume of finely fragmented ash that caused such disruption during last year’s Eyjafjallajokull eruption.”
(images via: Daily Mail UK)
Rothery issued his statement on May 22nd; by the next morning it was being predicted the ash cloud from Grimsvotn could reach Scotland by the evening of May 23rd. Sure enough, by May 24th approximately 500 flights to Scotland, Northern Ireland land parts of Scandinavia had been cancelled as the ash cloud loomed ever closer, swept by strong prevailing winds.
Authorities base their predictions regarding the May 2011 ash cloud on several factors relating to time and type: Grimsvotn’s eruptions are usually short in duration and the particles it spews out are heavier than those expelled by Eyjafjallajokull. Thus, there’s less ash overall and it falls to earth faster & closer to the point of origin. Not good news if you’re flying in or out of Iceland… and driving’s no picnic either. Which reminds me: cancel that picnic!
Pardon the Int-Eruption
Grimsvotn’s current eruption may pale in significance with those of Eyjafjallajokull and other historic volcanic events in Iceland but don’t dismiss it too quickly. Check out the immense ash cloud produced on the eruption’s first day… it bears an uncanny resemblance to a thunderstorm’s supercell.
(images via: Freysteinn Sigmundsson)
Like thunderstorms, Grimsvotn’s clouds are both short in duration and at least somewhat predictable in nature. Photographers have taken advantage of these characteristics and it seems with every eruption a flood of high quality images are captured and released. The set above, by native Icelander Freysteinn Sigmundsson, beautifully documents Grimsvotn’s December 1998 eruption.
(image via: Mamatus)
Predictability is fine, but don’t take it as gospel even in Grimsvotn’s case. While we appreciate the magnificent photos intrepid cameramen (and camerawomen) have given us, flying a plane anywhere near any erupting volcano is like rolling the dice with Thor. Much better to be the photographer on the airplane who’s photographing the photographer on the plane that’s circling alarmingly close to Grimsvotn’s ash plume… you can say that again!