Glacial Outburst Flood Has Begun in Grímsvötn

Vatnajökull Grímsfjall Grímsvötn Bárðarbunga Kverkfjöll Jöklar Jökull Vísindi

A glacial outburst flood has begun in Grímsvötn beneath Vatnajökull glacier, experts have confirmed. An M4.3 earthquake at Grímsfjall this morning alerted experts to increased activity at the site. While such floods are known to increase the likelihood of volcanic eruptions, there are no indications an eruption is imminent at the site.

In an interview with RÚV, Professor of Geophysics Magnús Tumi Guðmundsson confirmed the glacial outburst flood began several days ago in the highland region. Elevated water levels have already reached inhabited areas further south, but they are not significant. “There is more water in Gígjukvísl river,” Magnús Tumi stated. “However, this is not a big event, it just looks like the summer water levels. It’s not a lot and it’s equivalent to a small or medium-sized glacial outburst flood in Skaftá river.”

Strongest earthquake in a long time

The M4.3 earthquake that occurred just before 7:00 AM this morning is “noteworthy,” according to Magnús Tumi. He says it’s “the biggest one we know of there for a very long time.” The earthquake hasn’t been followed by others of a similar magnitude, however, and appears to be a one-off event.

What is a glacial outburst flood?

Grímsvötn is an active volcano located beneath Vatnajökull, Iceland’s largest glacier. It has the highest eruption frequency of all the volcanoes in Iceland, but is located far from any inhabited areas. The geothermal and volcanic activity at Grímsvötn causes regular glacial outburst floods, known as jökulhlaup. Such outbursts are triggered by geothermal heating beneath the glacier which causes ice to melt, and eventually be abruptly released from beneath the glacier, into the surrounding water systems.

Magnús Tumi says Grímsvötn is now in a period of increased activity, which typically lasts between 60-80 years. It last erupted in 2011.

Geothermal Heat Exposes Glacial Cliffs

Fifty-metre [164 ft] high cliffs have emerged to the west of Grímsvötn volcano in southeast Iceland after having been covered by the Vatnajökull glacier for fifty years, RÚV reports. Geophysicist Magnús Tumi Guðmundsson says that increased volcanic activity and geothermal heat, not climate change, are responsible for the glacial melt that has recently uncovered the towering rock walls. The Icelandic Glaciological Society discovered the cliffs on a spring outing in the area.

Grímsvötn is located on the west side of Vatnajökull glacier and is the most active volcano in Iceland. Over the last few decades, its activity has increased, and the resultant heat has melted part of the glacier.

“If we’d talked about this twenty years ago,” Magnús Tumi continued, “I’d have said it meant that Grímsvötn would see [an increased accumulation of water]. What’s happened over the same time period, however, is that the geothermal heat has shifted such that water does not accumulate in Grímsvötn like it did up until 1996.” Magnús Tumi said this indicates that the melt that led to the cliffs being revealed was not triggered by global warming.

Researchers will better explore the cliffs once they’ve emerged more from the side of the glacier. “This is part of a caldera,” he continued. “These are steep cliffs. What you can see of the largest of them is at least 50-metres high. If this continues, they’ll be even bigger.”

Newly uncovered cliffs have been found in three spots around Grímsvötn, but Magnús Tumi says it may not be long before more show their faces. “There are cliffs that haven’t emerged yet that were named in the 50s, Depill and Mósar, which we’ll hopefully be seeing soon.”

Speculations on Imminent Katla Eruption Were Premature, Says Geophysicist

Reports that the formidable Katla volcano is gearing up for an imminent eruption were premature, says a leading geophysicist. RÚV reports that a recent publication co-authored by Cambridge-educated (and Iceland-raised) volcanologist Evgenia Ilyinskaya identifies Katla as a “a globally important source of atmospheric carbon dioxide (CO2).” Although some have concluded from this discovery that Katla is signaling an imminent eruption, however, Magnús Tumi Guðmundsson, a professor in geophysics at the University of Iceland, says that the only conclusion that can be drawn is that more research is needed in order to know what the carbon emissions actually signify.

There is no way to know if Katla’s significant CO2 emissions indicate that it’s about to erupt because there’s no existing data to show whether those emission levels are normal for the volcano, Magnús wrote in a post on Facebook, and nor is it known how long they’ve been going on. “Even more unclear is whether these massive emissions are directly connected to an underground magma chamber, or what [Katla’s] connection to the magma chamber in the volcano is. It’s possible that Katla works as a kind of vent or exhaust channel for gasses that are emitted from magma deep under the southern part of the volcano belt.”

It bears noting that the original article itself makes no claims that Katla is about to erupt. Rather, “Globally significant CO2 emissions from Katla, a subglacial volcano in Iceland,” which was published in the journal Geophysical Research Letters last week, states that although researchers understand volcanoes to be “a key natural source of atmospheric CO2,” the current “estimates of the total global amount of CO2 that volcanoes emit are based on only a small number of active volcanoes.” As such, Evgenia and her colleagues conducted “high‐precision airborne measurements and atmospheric dispersion modelling” and were thus able to show that “Katla, a highly hazardous subglacial volcano which last erupted 100 years ago, is one of the largest volcanic sources of CO2 on Earth, releasing up to 5% of total global volcanic emissions.”

The “remarkable measurements” in the article “show that there’s still a lot we don’t know about volcanic activity and the characteristics of specific volcanoes,” wrote Magnús. “As the authors of the article point out, the conclusions call for more thorough measurements. It is, for instance, important to know whether the emissions are constant, or connected to a particular time of year. It’s possible that more measurements will shed new light on Katla’s behavior and could in this way help us further improve monitoring and risk assessment. More measurements are the only way to make a reliable assessment of the volcano’s total emissions.”

Once those measurements are in hand, says Magnús, scientists will need to reassess “what the numbers tell us about the magma under Katla and what lessons can be learned from them.”

The original article—and a “plain language summary” of its findings—is available (in English) here.