Glacial flood considered likely

25.11.2021 - 10:34
Grímsvötn
 Mynd: Atlantsflug - Ljósmynd
The sinking of ice in the Vatnajökull glacier at Grímsvötn volcano indicates a flood of meltwater could soon occur. If it does, a volcanic eruption cannot be ruled out, according to geophysics professor Magnús Tumi Guðmundsson. Grímsvötn is one of Iceland’s most active volcanoes. The scientific council of the civil protection agency met yesterday to discuss the possible jökulhlaup flood.

According to information from the Met Office, the speed of sinking of the ice cave has been stable overnight and has sunk by 25 centimetres since yesterday morning, according to the Met Office GPS monitor. No change has been observed in Gígjukvísl river, however, where electrical conductivity, gas, and water levels remain stable. 

No dramatic start to flood 

Floods from Grímsvötn have regularly been followed by volcanic eruptions—most recently in 2004. 

“It is a realistic possibility and people are following it closely and are awake to the possibility that it could happen. It would be when it starts sagging during the last phase of a jökulhlaup. That would be the most likely,” Magnús Tumi told RÚV radio this morning. 

He adds that the start of jökulhlaup floods from Grímsvötn are not spectacular events like those from volcanic systems under some other glaciers in Iceland. 

“Water just starts trickling, then it rises slowly but surely. It's only the nose that decides [whether it’s a jökulhlaup], or monitoring equipment. There is no tidal wave. It’s not like that.” 

Lots more water than the Skaftá flood this summer 

It is believed the flood will peak at around 5,000 cubic metres per second, which would probably mean little or no impact on roads and bridges across Skeiðarársandur. Magnús Tumi says, though, that there is a lot more water in Grímsvötn now than there has been during the past 25 years. 

“In Grímsvötn today, there is maybe three-or-four-times more than there was in the eastern Skaftá cauldron which released this summer. If we look further back, there was often a lot more water in Grímsvötn. They have changed a lot. But this is a lot more than there has been for the past 25 years.” 

As mentioned above, Grímsvötn is one of Iceland’s most active volcanoes and last erupted in 2011, 2004, and 1998. 

The above photograph of Grímsvötn was taken in August 2020

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