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.

Glacial Outburst Flood Has Begun in Skaftá River

A glacial outburst flood has begun in Skaftá river in South Iceland, the Icelandic Met Office reports. The water level and flow rate in the river began to increase last night and increased electrical conductivity was also measured. Rangers in Hólaskjól also reported smelling sulphur in the area. The National Police Commissioner and Department of Civil Protection have issued an uncertainty phase due to the event.

The last glacial outburst flood in Skaftá occurred two years ago, in September 2021. Floods in Skaftá are sourced from two ice cauldrons beneath Vatnajökull glacier which usually burst one at a time, but it is possible that this flood is sourced by both the western and eastern cauldrons, according to the Met Office. The 2021 glacial outburst flood was sourced by both cauldrons.

Risk of floods and gas poisoning

There are several hazards associated with such natural events. Firstly, flood conditions are expected in Skaftá river over the next two to three days and some flooding of roads near the river is possible. Secondly, hydrogen sulphide is released from the floodwater as it drains from the Vatnajökull ice cap. The gas is particularly potent at the ice margin, where it can reach poisonous levels of concentration. Travellers are advised to stay away from the edges of Skaftárjökull, Tungnaárjökull, and Síðujökull, where floodwater could burst through the surface. Lastly, travellers on Vatnajökull should stay away from the region, as crevasses will develop rapidly around the ice cauldron.

The cauldrons that source the glacial outburst floods in Skaftá drain every two years on average, producing floods of up to 1,500 cubic metres per second.

Glacial Outburst Flood Will Likely Peak on Sunday

The glacial outburst flood, or jökulhlaup, which started when the ice sheet in the Grímsvötn volcano beneath Vatnajökull glacier began to melt 11 days ago, is predicted to reach its peak on Sunday. At time of writing, the Icelandic Road and Coastal Administration does not believe that the runoff will affect traffic on Route 1 in South Iceland, nor that roads will need to be closed.

As of Friday morning, the Met Office reported that Grímsvötn ice sheet had sunk over 27m [89 ft] and was flooding the Gígjukvísl river at a rate of 1600 m3/s [56503 f3/s]. The electrical conductivity of the river, which is an indicator of how much geothermal meltwater it has taken on, has also been increasing and was measured above 464 µS/cm on Friday. The gas concentrations along the perimeter of the glacier have been measured at higher than normal levels, but do not currently pose a danger.

In the past, eruptions at Grímsvötn have begun following a glacial outburst flood. Per the Met Office, “[t]he loss of the water from Grímsvötn lake reduces the pressure on top of the volcano and this can allow an eruption to begin.” This happened in 1922, 1934, and later, in 2004, when an eruption beginning three days after a flood began. In that instance, there were a series of earthquakes before the eruption. But no earthquakes have been measured around the volcano at present.

Skaftá Glacial Outburst Flood to Reach its Peak on Wednesday

A second glacial outburst flood began in the eastern Skaftá ice cauldron under Vatnajökull glacier late Saturday evening, RÚV reports. This flood follows a smaller one that originated in the western Skaftá ice cauldron and is expected to do as much damage to local communities and farmland as the last glacial outburst flood on the Skaftá river in 2018. The Department of Civil Protection is strongly advising that travelers stay away from the area and has raised their emergency response level to Alert Phase.

Floods in Skaftá are sourced from two ice cauldrons, formed due to persistent geothermal activity beneath Vatnajökull. On average, the cauldrons drain every two years, producing floods of up to 1,500 cubic metres per second. When the interval between floods is short, the flood tends to be smaller. The eastern cauldron is responsible for the largest floods. The river has flooded at least 58 times since 1955, with each cauldron usually draining at a two-year interval.

 

Image courtesy of Þuríður Hallgrímsdóttir. Route 1 west of the village of Kirkjubæjarklaustur flooded during the Skaftá glacial outburst flood in 2018

Smaller Flood, Same Damage
Owing to the speed at which the glacial flood began and water level increases in the first twelve hours of the flood, experts believed that the current outburst flood would be as big as the one in 2015, which is the largest such flood on record.

Happily, flood waters have been steadily abating since late Monday evening, leading experts to revise their original predictions. Nevertheless, major and widespread flooding is still a risk in the area. At time of writing, the flow at Eldvatn lake on the Skaftá river was just over 520 m3/s [18,363 ft3/s]. Flooding is expected to reach its peak tomorrow, Wednesday September 8, and waters are expected to continue to flood the region for another day or so after that.

Unfortunately, although the flood itself is expected to be smaller than it was in previous years, experts anticipate that it will do the same level of damage to surrounding settlements and farmland. This is, in part, because recent rains and runoff from the western ice cauldron, which flooded days before, have saturated the ground. As such, flood waters are more likely to spread further than they normally would.

‘We’ll just have to cross our fingers’

Glacial outburst floods are simply an unfortunate but unavoidable part of daily life for people in the area, remarked Skaftá district manager Sandra Brá Jóhannsdóttir in an interview on Tuesday before departing on a Coast Guard surveillance flight to determine what damage the flood has incurred thus far.

Authorities were particularly concerned about the wellbeing of the sheep grazing in the surrounding valleys. Local farmers spent the morning gathering their flocks and moving them to safer pastures in the event that the flood does continue to spread. Thankfully, no significant damage to structures or livestock had been reported at time of writing. “We’ll just have to cross our fingers,” said Sandra Brá. “It’s our hope, first and foremost, that the flooding is at least still at a consistent level and that hopefully, it will start to go down so that there will be less damage that occurred [in the area] in 2018 and 2015.”

The Skaftá glacial outburst flood in 2015 caused damage in the hundreds of millions of ISK (roughly $761,000; €708,000 at the time) and ten farms suffered damage to cultivated land and pasture. In 2018, flood waters covered Route 1, west of Kirkjubæjarklaustur.

See Also: Live Footage of the Skaftá Glacial Outburst Flood

In addition to warning that roadways in the area could quickly become impassable in the coming days, the Department of Civil Defense notes that glacial outburst floods can create hydrogen sulphide pollution, which can cause damage to the mucus membranes in the respitory tract and the eyes. Travelers are strongly advised to stay away from the area, which includes the Skaftárdalur valley near the southern coastal village of Kirkjubærjarklaustur, as well as around the Skaftárjökull, Tungnárjökull, and Síðjökull glaciers.

Glacial Outburst Flood Likely Begun in Skaftá

Electrical conductivity readings from the Skaftá river have increased and water levels by Sveinstindur have increased this morning, signifying that a glacial outburst flood is in progress. It is likely that the flood originated from the western Skaftá ice cauldron which last drained in 2019, although it is not impossible that a flood from the eastern cauldron might follow.

In addition to rising water levels and increased electrical conductivity, the Iceland Meteorological Office has also been notified of sulfuric smell in the area around Skaftá and Hverfisfljót. It is believed that the changes are not due to melting glaciers or rain, but rather that a glacial outburst flood has begun. Data suggests that the flood origin is in the western ice cauldron in the Vatnajökull glacier, which last flooded in September 2019. The western ice cauldron usually produces smaller floods than the eastern one.

The flow of Skaftá by Sveinstindur was around 290 m3/s at noon today but the Met Office doesn’t expect the maximum flow during this flood to surpass 750 m3/s. However, there is a possibility that water drains from the eastern ice cauldron on the heels of the current flood from the western one, as happened in August 2018.

It’s important that everyone who is travelling in the flood area is conscious of the situations that can arise and that travellers are well informed of the situations:

  • Flood conditions are expected in Skaftá over the next two to three days. Some flooding of unpaved roads close to Skaftá is possible.
  • Hydrogen sulphide is released from the floodwater as it drains from the Vatnajökull ice-cap. The gas is particularly potent at the ice margin, where concentrations will reach poisonous levels. Travellers must stay away from the edges of Skaftárjökull, Tungnaárjökull and Síðujökull while the flood occurs.
  • Crevasses will develop rapidly around the ice cauldron, so travellers on Vatnajökull should stay away from the region, including the lower part of Skaftárjökull and Tungnaárjökull, where floodwater could burst through the surface.

Floods in Skaftá are sourced from two ice cauldrons, formed due to persistent geothermal activity beneath Vatnajökull. On average, the cauldrons drain every two years, producing floods of up to 1,500 cubic metres per second. When the interval between floods is short, the flood tends to be smaller. The eastern cauldron is responsible for the largest floods. The river has flooded at least 58 times since 1955, with each cauldron usually draining at a two-year interval.

Glacial Outburst Flood Expected This Month

The Met Office continues to monitor Múlakvísl river closely, as a glacial outburst flood is expected in the river this month, RÚV reports. Conductivity is high in the South Iceland river, measuring around 170 microsiemens per centimetre, and water levels in the river are relatively high, says Sigurdís Björg Jónasdóttir, a specialist at the Met Office. Sigurdís says these conditions have been steady throughout July and it is difficult to say when the flood will begin.

In recent years, Múlakvísl river has experienced a glacial outburst flood annually, with the exception of last year. Experts are expecting a larger flood this year, however. Eyjólfur Magnússon, a glacial research specialist at the University of Iceland, told the news agency that the flood would likely occur this month.

Specialists expect the flood’s onset to be sudden. The river’s last glacial outburst flood was detected only 45 minutes before it began. Múlakvísl flows under Route 1 in South Iceland, so it is possible the flood could affect traffic in the area.

No Signs Yet of Imminent Múlakvísl Glacial Outburst Flood

So far, there have been no clear signs of the Múlakvísl jökulhlaup, or glacial outburst flood, which is expected to happen in the coming days or weeks. A GPS monitor has been put up in one of the calderas in Mýrdalsjökull glacier which will give more information on the timing of the flood. Salóme Jórunn Bernharðsdóttir, a natural hazard specialist at the Icelandic Meteorological Institute, states the institute is watching proceedings in Múlakvísl closely. So far, there have been no signs that the glacial outburst flood has started.

The newly installed GPS monitor is hoped to give clues about an imminent flood one to two days before the flood reaches the Múlakvísl river crossing at Route 1. Salóme stated that earthquake measurement devices should also display some disturbances around four to six hours before the flood reaches the bridge. Furthermore, electric conductivity should increase in Múlakvísl river before the flood happens. When water levels have risen at Léréftshöfuð, which is six kilometres north of the Múlakvísl river, the flood will reach the Route 1 crossing in half an hour to an hour.

The geothermal heat under the Mýrdalsjökull glacier causes water to collect in the calderas, causing regular glacial outburst floods in the area. Normally, the floods take place a little later in the summer when the mid-summer thaw at Mýrdalsjökull. The amount of water under Mýrdalsjökull glacier has led scientist to believe a glacial outburst flood is imminent. Last year, 2018, there was no flood so a considerable amount of water has collected under the glacier. The flood is expected to be the largest one in eight years, when the 2011 flood ruptured the Route 1 crossing the Múlakvísl river east of Vík í Mýrdal.

Information for travellers
At this point in time, it is believed that it is not necessary to close roads. That situation could change quickly, however, and authorities will step in if they believe a flood is about to occur.

What can happen, and how should travellers react?
Dangers which accompany a glacial outburst flood in Múlakvísl river:
– Floodwater can block the route from Route 1 towards Kötlujökull glacier west of Hafursey.
– Floodwater can flood over and block, or even rupture, Route 1 at the bridge crossing of Múlakvísl river.
– Floodwater can block the route into Þakgil.
– The gas hydrogen sulphide could be found in copious amounts close to Múlakvísl river. The gas can burn mucous membrane in the eyes and in the respiratory tract

Instructions:
– Respect road closures, as well as evacuations if they should occur.
– Keep away from the Múlakvísl river when a glacial outburst flood is occurring.
– Avoid places affected by gas pollution, such as along the river as well as in depressions nearby by it. Do not stop at the bridge crossing Múlakvísl or Skálm.

For those looking to keep a watchful eye on the proceedings when the flood occurs, this webcam of the Láguhvolar area should provide a view of the flood: http://brunnur.vedur.is/myndir/webcam/2019/07/04/webcam_laguhvolar.html

Travellers passing through the area are instructed to head to the website of the Icelandic Road and Coastal Administration, www.road.is, for further information on road conditions, or call 1777.

Glacial Outburst Flood in Múlakvísl Expected

Measurements from Mýrdalsjökull glacier indicate that a glacial outburst flood could occur in Múlakvísl river in the next days or weeks. A relatively large flood is expected, the largest in the last eight years. Authorities do not expect to have to enforce closures on roads at this point in time, but they will follow developments in the area closely. Closure of Route 1 might occur. The Department of Civil Protection and Emergency Management reported this yesterday, and will continue to monitor the situation.

The results from The Institute of Earth Sciences at the University of Iceland indicate that enough water has collected below geothermal heat calderas in the eastern part of Mýrdalsjökull glacier. The water flow during the height of the glacial flood could be significantly more than the flood which took place in 2017, but likely less than the severe flood of 2011. The flood in 2011 destroyed the bridge on Route 1 crossing the Múlakvísl river east of Vík í Mýrdal.

Regular flooding of Múlakvísl
Small glacial floods have occurred in Múlakvísl river almost yearly in the last couple of years, close to or right after mid-summer when the thaw in Mýrdalsjökull glacier is at a high point. Those floods have most often been small enough that the river does not flow out of the riverbed, and have therefore not caused any damages. There was no glacial outburst flood in 2018. The flood in 2017 was considered significant although it did not cause any damages. However, the flood in 2017 caused significant air pollution due to the release of hydrogen sulphide. In the last 100 years, there have been at least two severe glacial outburst floods in Múlakvísl, in 1955 and 2011. In both of those floods, the bridge crossing Múlakvísl river was ruptured. For scale, the flood in 2017 is estimated to have been to the tune of 200 cubic metres per second near the Route 1 crossing, which was 20% of the maximum water flow in the 2011 flood in the same site.

“We’ve performed measurements in the same calderas four times since 2017. We can expect that the flood will be the largest flood which has occurred in Múlakvísl in the last eight years. In all likelihood, it will be significantly smaller than the 2011 flood which ruptured the bridge, but nonetheless, it would be the largest flood since then. The main explanation is the fact that there was no outburst from these calderas last summer,” said Eyjólfur Magnússon, a glacial research expert at The Institute of Earth Sciences at the University of Iceland in an interview with RÚV. The warmth in Iceland this summer could be causing an earlier flood than usual, according to Eyjólfur. “It could be causing that this flood will happen sooner than usual. These calderas often have outbursts in July or the beginning of August. That has been the main rule. It seems to be so that the summer thaw is starting this flood. So it seems to be often that these calderas empty when the summer thaw is at high-point up on the glacier, or soon after that.

There is considerable geothermal heat under Mýrdalsjökull glacier which creates about 20 calderas on the surface of the glacier. The heat melts the glacial ice and the meltwater collects under the geothermal calderas. In addition to this, thaw water from the surface of the glacier seeps through the glacier and is added to meltwater collecting below the glacier. When enough water has collected, it breaks out from under the glacier and causes the glacial outburst flood.

Members of the travel industry in the nearby area have been informed of the danger. If a flood should occur, they will be informed of further proceedings right away. Scientists believe that the flood will come with some prior warning, and they are now working on putting up a GPS measurement device in one of the sub-glacial calderas to measure proceedings more accurately.

At this point in time, it is believed that it is not necessary to close roads. That situation could change quickly, however, and authorities will step in if they believe a flood is about to occur.

What can happen, and how should travellers react?
Dangers which accompany a glacial outburst flood in Múlakvísl river:
– Floodwater can block the route from Route 1 towards Kötlujökull glacier west of Hafursey.
– Floodwater can flood over and block, or even rupture, Route 1 at the bridge crossing of Múlakvísl river.
– Floodwater can block the route into Þakgil.
– The gas hydrogen sulphide could be found in copious amounts close to Múlakvísl river. The gas can burn mucous membrane in the eyes and in the respiratory tract

Instructions:
– Respect road closures, as well as evacuations if they should occur.
– Keep away from the Múlakvísl river when a glacial outburst flood is occurring.
– Avoid places affected by gas pollution, such as along the river as well as in depressions nearby by it. Do not stop at the bridge crossing Múlakvísl or Skálm.

Travellers passing through the area are instructed to head to the website of the Icelandic Road and Coastal Administration, www.road.is, for further information on road conditions, or call 1777.

Ring Road Closure Due to Flood Continues

Route 1, the Ring Road, remains closed at Kirkjubæjarklaustur due to a glacial outburst flood in Skaftá river, RÚV reports. Authorities are now evaluating whether to breach the road and build a channel to drain the area.

Though the road is closed to smaller vehicles, larger cars and jeeps have been permitted to pass through. Smaller vehicles can bypass the closure via Road 204 through Meðalland.

“There is just a large catchment area that has been formed there, I just have no idea when it will recede, that’s just how it is,” said Ágúst Bjartmarsson of the Icelandic Road and Coastal Administration. “This is over a kilometre long catchment area and lots of water behind it.”

Travellers are advised to check conditions at road.is before setting out.

Update August 9, 2018: The Ring Road has been opened to traffic at Kirkjubæjarklaustur.

Route 1 Partially Closed Due to Skaftá Glacial Flood

Route 1, west of Kirkjubæjarklaustur, has been closed due to flooding from the glacial outburst flood in Skaftá river, Vísir reports. The police in South Iceland have reported this, and the Icelandic Met Office issued a general travel advisory on June 3rd.

Ágúst Freyr Bjartmarsson, a foreman at the Icelandic Road and Coastal Administration, said the water is now too deep for cars to pass through, but that it cannot be said for sure when water levels will regress.

A bypass route through Meðallandsvegur is open, which is expected to slow down travellers by around 40 to 60 minutes in total.

The glacial outburst flood has already reached a high point, and it is expected that it will now slowly regress, according to the Icelandic Met Office. The effects of the flood will still be felt in the next days, and it is expected that Skaftá will not experience regular water flow until later in the week.

The fact that both cauldrons of the glacier Skaftárjökull have flooded at the same time is an historical event, as up to this point only one cauldron at a time has activated, Vísir reports.

A sulphur stench has been reported in the region, but the smell can be felt quite far away. The were reports of sulphur in the air in Norway the last time a glacial outburst flood in Skaftá happened, in 2015.

Travellers are advised to visit the website of the Icelandic Road and Coastal Administration for further information, www.road.is, or reach them by telephone in the number 1777.