Glacial Flood Expected in West Iceland

Hraunfossar Waterfalls

A relatively high water level in a glacier lagoon by Langjökull glacier, West Iceland, suggests that a flood can be expected from the lagoon in the near future. Such floods have occurred before and are known to cause a very rapid water level rise in the rivers Svartá and Hvítá in the Borgarfjörður area.

The Volcanology and Natural Hazard Group and the University of Iceland published satellite images of the lagoon and surrounding area yesterday, showing a high water level in the lagoon. At least three floods have occurred from the lagoon before in the last few years; in August 2020, August 2017, and September 2014.

Eldfjallafræði og náttúruvárhópur Háskóla Íslands / Facebook. 

Typically, the floodwater runs under the glacier toward the southwest, where it runs into Svartá and then from that river into Hvítá. The Icelandic Met Office is monitoring the situation, in part with water level measuring equipment in Hvítá, which will be able to detect the peak of the flood.

The flooding could be dangerous to those travelling on or near the two rivers.

Unusual Activity at Grímsvötn Volcano: Aviation Code Raised to Orange

Grímsvötn Gígjukvísl

The Icelandic Met Office has raised the elevation colour code at Grímsvötn volcano from yellow to orange due to elevated seismic activity at the site. The glacial flood from Grímsvötn reached its peak discharge yesterday morning. Seismic activity at the site has been increasing above the normal level for the past two days or so, and a magnitude 3.5 earthquake occurred at the volcano just after 6:00 AM this morning.

Despite strong earthquakes detected this morning, no volcanic tremor has been detected at Grímsvötn and no increases or changes in geochemical emissions at the volcano have been measured. According to a notice from the Met Office, the seismic activity “is possibly occurring due to the decreased pressure above the volcano, since the flood water left Grímsvötn sub-glacial lake. According to calculations from the Institute of Earth Sciences at the University of Iceland at least 0.8 km3 of water have drained from the sub-glacial lake.”

Grímsvötn volcano is located in the Icelandic highland, underneath Vatnajökull, the country’s largest glacier. It last erupted in 2011 and emitted about 0.8km3 of basaltic tephra. It erupts roughly once every ten years and the eruptions are accompanied by glacial floods such as the one that is currently winding down.

Read more about the glacial outburst flood at Grímsvötn.

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.

Glacial Flood at Grímsvötn Not Imminent, But Expected This Year

GPS measurements taken at Grímsvötn volcano in Southeast Iceland show that the land there is starting to rise again, RÚV reports. Scientists say this means that there will not be a glacial flood in the immediate future, as was thought a possibility only days ago.

See Also: Glacial Flood May Have Begun at Grímsvötn Volcano

Scientists and Civil Defense authorities have been closely monitoring the area around Grímsvötn all weekend. “Our data indicate that a glacial flood isn’t imminent right now, but the water level in Grímsvötn is very high, so we fully expect that there will be a flood this year,” explained Kristín Jónsdóttir, coordinator of the Icelandic Met Office’s Earthquake Hazards team. Glacial meltwater collects in a subglacial lake and caldera in Grímsvötn’s core, both of which are covered by an ice cap. The water level of the lake rises slowly but surely, until finally, it overflows in a glacial flood.

Grímsvötn, located under the Vatnajökull ice cap, is the most active volcano in Iceland and has erupted as many as 100 times since the time of Iceland’s settlement, and 13 times since 1902. It is part of a volcanic system that is over 100 km long and extends down to the Laki craters. Grímsvötn last erupted in 2011—the volcano’s largest eruption in 140 years.

A glacial flood at Grímsvötn can trigger a volcanic eruption. Although these eruptions can be strong, the primary side effect has usually been disruptions to air traffic. If there is an eruption of Grímsvötn in coming year, scientists say it is unlikely to be as big as the one in 2011.

Grímsvötn will continue to be closely monitored, with scientists travelling to the area on Sunday to conduct checks on the equipment there.

Glacial Flood May Have Begun at Grímsvötn Volcano

There are indications that a glacial flood may have begun at Grímsvötn volcano under the Vatnajökull ice cap in Southeast Iceland, RÚV reports. Chief Superintendent of South Iceland police Oddur Árnason confirmed that police have been advised about the likeliness that a jökulhlaup is underway, but currently, the only solid data to confirm this is that GPS devices are registering changes in land elevation surrounding the volcano.

Finnur Pálsson, an engineer at the University of Iceland’s Earth Sciences Institute, oversees the measurements taken at Grímsvötn. Glacial meltwater collects in a subglacial lake and caldera in Grímsvötn’s core, both of which are covered by an ice cap. The water level of the lake rises slowly but surely, until finally, it overflows in a glacial flood. Finnur said that measurements showed the water levels under the volcano shifting by several centimetres yesterday but they’ve been stable ever since. In June, the water level of the subglacial lake was rising three centimetres a day in June, indicating that a flood could be imminent in coming weeks or months. Glacial floodwaters from Grímsvötn tend to run into the Gígjukvísl river and usually reach their apex within two to five days.

See Also: Evidence that Grímsvötn Volcano is Preparing for Next Eruption

Finnur says that it’s currently uncertain whether there are some inaccuracies in the data, or if a glacial flood truly has begun. As such, the area will be closely monitored today and for the next 24 hours. If a glacial flood has begun, it would take a considerable amount of time for the floodwaters to reach settled areas.

At time of writing, the Icelandic Met Office was convening a meeting regarding the possible event and Civil Protection had also been in touch with local authorities. Police stations in the district have been informed, but no preparations had been undertaken yet.

See Also: Largest Volcanic Eruption in Grímsvötn in 100 Years

Grímsvötn is the most active volcano in Iceland and has erupted as many as 100 times since the time of Iceland’s settlement, and 13 times since 1902. It is part of a volcanic system that is over 100 km long and extends down to the Laki craters. Grímsvötn last erupted in 2011—the volcano’s largest eruption in 140 years.

A glacial flood at Grímsvötn can trigger a volcanic eruption. Although these eruptions can be strong, the primary side effect has usually been disruptions to air traffic. If there is an eruption of Grímsvötn in coming days or weeks, scientists say it is unlikely to be as big as the one in 2011.

Evidence that Grímsvötn Volcano is Preparing for Next Eruption

Vatnajökull Grímsfjall Grímsvötn Bárðarbunga Kverkfjöll Jöklar Jökull Vísindi

The Scientific Advisory Board of Iceland’s Civil Protection Department is meeting today to discuss the latest measurements done at Grímsvötn volcano. Recent gas measurements indicate there is magma near the surface of the volcano and the volcano may be preparing for an eruption. Grímsvötn last erupted in 2011 and erupts on average every 5-10 years during active periods.

Earlier this month, scientists from the Icelandic Met Office measured sulphur dioxide (SO2) in the southwest corner of the caldera in Grímsvötn, close to where the last eruptions in 2004 and 2011 took place.  “This is the first time that we measure so much SO2 at a volcano in Iceland that is not in an eruptive phase and its presence is indicative of magma at shallow level,” says Melissa Anne Pfeffer, a specialist at the Met Office who participated in the recent trip on Vatnajökull glacier. In addition to the high level of SO2, Melissa also reports that the area where geothermal activity can be detected at the surface of the volcano has notably increased.

Grímsvötn measurements June 2020
A specialist of Iceland Icelandic Met Office performs gas measurements in Grímsvötn, June 2020. Photo: IMO/Melissa Anne Pfeffer.

Experts say an eruption in Grímsvötn could be triggered by a glacial flood, as the removal of a large volume of water stored in the lake could facilitate the magma rising to the surface and trigger an eruption. “Therefore, the possibility of an eruption triggered by a glacial flood, which could occur in the coming weeks or months, has to be considered,” a notice from the Met Office states. “However, this may not be the case, and the next glacial flood may not lead to an eruption.”

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.

Skaftá Glacial Flood Ends

The glacial outburst flood that has been taking place along the Skaftá river in South Iceland has mostly ended reports the Icelandic Met Office.

According to an announcement on the Met’s website, “Water discharge in Skaftá is back to normal for this time of year. The Skaftá flood is therefore mostly over.” The announcement emphasizes, however, that both discharge and water height in both the Grenlækur and Tungulækur streams are still high. It’s estimated that these will return to normal levels in a little over a week.

The Icelandic Met Office issued a travel warning about the glacial flood a week ago, and since then, part of Route 1, the Ring Road, had to be closed at Kirkjubæjarklaustur due to rising water levels.

Travelers are reminded to check road conditions at road.is before setting out on their trips.