The volcanic eruption that recently occurred near the Icelandic port of Grindavik confirms the awakening of a long fault from which magma could erupt again in the coming years, almost without warning, a specialist in these phenomena tells AFP.
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According to Icelandic Civil Protection, volcanic activity appeared to have subsided on Monday, a day after an eruption that affected Grindavik on the Reykjanes peninsula southwest of Iceland.
This large island in the North Atlantic, the largest and most active volcanic region in Europe, lies on the Mid-Atlantic Ridge. This crack in the ocean floor that separates the Eurasian and North American tectonic plates is the subject of much attention.
The Grindavik eruption is the fifth in three years to affect the Reykjanes Peninsula.
“After eight centuries of relative pause and complete cessation of surface activity, we have entered a new episode of plate separation that may last several years, possibly a decade,” explains volcanologist Patrick Allard of the Paris Institute of Globe Physics.
Shortly before March 2021 and the first eruption of this series of five events, “we saw the ground deforming, magma rising from the depths and intruding into the fault,” the scientist continues.
The presence of this large amount of magma near the surface led to a series of eruptions. The last two (on December 18th and then on January 14th near Grindavik) were very short and preceded by little seismic activity, “testifying to the fact that the magma is very close to the surface and ready to erupt is”.
The Earth's thin crust will facilitate these “pressure releases,” with quantities of magma released into the open that are “not likely to be huge.”
However, locating the error is problematic. It threatens the Svartsengi geothermal power plant, located in the same area, which supplies around 30,000 residents, around a tenth of Iceland's population, with water and electricity.
And the uncertainty “raises the question of the existence of this port city” Grindavik, “built on the rivers 800 years ago,” adds Patrick Allard.
With a very short warning time before an outbreak. The last two were thus “preceded by just a few hours of a seismic crisis associated with the final rupture of this new rising magma.”
In addition to the risk of an eruption in the city itself, there is a risk of an underwater eruption with “explosive phenomena that release further volcanic ash and fragments.”
An economic but also social impact: the 4,000 inhabitants of Grindavik were evacuated in November, which on a French scale would be equivalent to emptying “a city of 700,000 inhabitants,” notes the volcanologist.