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Large fissure opens up in Grímsfjall, Iceland

A large fissure opened up last week in the southern part of Grímsfjall, near Grímsvötn subglacial volcano in Iceland. Pictures show that there’s a lot of hydrothermal activity in this fissure, but there is no eruption at this moment.

The fissure opened between driving points that are often called A1 and A2, according to the descriptions of Andra Gunnarsson, who posted photos of the crack on his Facebook page. 

“It can be difficult to spot the crack [from the ground] as there is scraping on top of it. It would be advisable for travelers to drive a little south of the traditional route,” Gunnarsson added. 

“Based on recent history, this strongly suggests that this is the area where the next eruption is going to happen in Grímsfjall [Grímsvötn] volcano. When and how big such eruption is going to be is impossible to know,” Jón Frímann of Iceland Geology noted.1

The fissure is located around Lat: 64° 24′ 13,476″ N Lon: 17° 13′ 57,282″ W.

The fissure is possibly growing and has made holes in the glacier large enough to swallow large cars, Frímann said.

Gunnarsson also said he has noticed four smaller cracks along the way, which are brand new.2

The fissure formed less than two weeks after a new glacial flood started at Grímsvötn, prompting authorities to raise the Aviation Color Code to Yellow and announce the State of Uncertainty.3

Geological summary

Grímsvötn, Iceland’s most frequently active volcano in historical time, lies largely beneath the vast Vatnajökull icecap. The caldera lake is covered by a 200 m (650 feet) ice shelf, and only the southern rim of the 6 x 8 km (3.7 x 5 miles) caldera is exposed.

The geothermal area in the caldera causes frequent jökulhlaups (glacier outburst floods) when melting raises the water level high enough to lift its ice dam.

Long NE-SW-trending fissure systems extend from the central volcano. The most prominent of these is the noted Laki (Skaftar) fissure, which extends to the SW and produced the world’s largest known historical lava flow during an eruption in 1783.

The 15 km3 (3.6 mi3) basaltic Laki lavas erupted over a 7-month period from a 27 km (16.7 miles) long fissure system. Extensive crop damage and livestock losses caused a severe famine that resulted in the loss of one-fifth of the population of Iceland.4

References:

1 Fissure opens up in south Grímsfjall volcano (no eruption) – Iceland Geology – October 22, 2022

2 Sprunga á Grímsfjalli „sem étur bíla léttilega“ – mbl.is – October 22, 2022

3 Glacial flood in Grímsvötn, Aviation Color Code raised to Yellow, Iceland – The Watchers – October 12, 2022

4 Grímsvötn – Geological summary – GVP

Featured image credit: Andri Gunnarsson

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