Magma is flowing in a 15-kilometer-long fissure 800 meters underground just outside the coastal town of Grindavik, according to the authorities’ latest models.
“It must be noted that the data on which the models are based is 12 hours old and therefore it must be assumed that the magma has risen closer to the surface,” the Icelandic civil protection agency wrote on Saturday evening.
Grindavik, home to around 4,000 people, was evacuated during the night of Saturday.
Exactly where an eruption may occur is still unclear, but based on where the magma has penetrated, the probability of an eruption in the sea just outside the city has increased.
“Because the seismic activity is so great in the area, we cannot expect to see the small earthquakes that signal the beginning of an eruption,” writes the civil protection authority.
Grindavik is located about four miles southwest of Reykjavik, and close to the Svartsengi geothermal plant, the main supplier of electricity and water to 30,000 inhabitants on the Reykjanes Peninsula.
Iceland, and Reykjanes in particular, lies directly over the “Mid-Atlantic Ridge”, where the Eurasian and North American continental plates meet. This means that volcanic eruptions are very common. But most of the time they are so discreet, or happen so remotely, that they do not pose any major acute danger.
Reykjanes in particular has suffered three eruptions in as many years: in March 2021, August 2022 and July this year.