Iceland is preparing to protect geothermal power plants from the threat of a volcanic eruption

GRINDAVIK, Iceland (Reuters) – Icelandic authorities on Tuesday prepared to build defensive walls around a geothermal power plant in the southwestern part of the country that they hope will protect it from lava flows amid fears of an imminent volcanic eruption.

Seismic activity and underground lava flows intensified on the Reykjanes Peninsula near the capital Reykjavik over the weekend, prompting authorities to evacuate nearly 4,000 people from the fishing town of Grindavik on Saturday.

The Icelandic Meteorological Institute said in a statement on Tuesday that the probability of an eruption remains high despite the decrease in seismic activity.

She added that nearly 800 earthquakes were recorded in the region between midnight and noon on Tuesday, which is fewer than the previous two days.

“Less seismic activity usually precedes an eruption, because you get so close to the surface that you can’t build up as much tension to cause large earthquakes,” said Ricky Pedersen, who heads the Nordic Volcanic Center and is based in Reykjavik.

“This should never be taken as a sign that an outbreak is not on the way,” she said.

Authorities said they were preparing to build a large dam designed to divert lava flows around the Svartsinje geothermal power plant, located just over 6 kilometers (4 miles) from Grindavik.

Justice Minister Gudrun Hafstinsdottir told state radio RUV that equipment and materials that could fill 20,000 trucks had been transported to the factory.

The construction of the protective dam around the power station was awaiting official approval from the government.

A spokesman for HS Orca, the power plant’s operator, said it was providing power to the entire country, although the outage would not affect power supplies to Reykjavik.

Almost all of Grindavik’s 3,800 residents were allowed to return home briefly on Monday and Tuesday to collect their belongings, Iceland’s Department of Civil Protection and Emergency Management said.

In Grindavik, long fissures occurred in the city centre, making the main street impassable, while steam could be seen rising from the ground.

Some houses still had their lights on, but the town was deserted behind the strange car and a handful of locals were there to collect their most important possessions before Grindavik was once again declared off limits.

Local resident Kristin Maria Birgisdottir, who works for the town’s municipality, told Reuters on Tuesday that she only had the clothes she wore to work on the day the town was evacuated.

“I am preparing in case I have the opportunity to visit my house and get some of my belongings,” said Birgisdottir, who moved to a summer house with her family.

Some residents had to be transported to Grindavik in emergency responders’ vehicles, while most residents were allowed to drive to Grindavik in their own vehicles accompanied by emergency personnel.

Most of the pets and farm animals had been rescued from Grindavík by Monday night, according to the Dervina charity.

During the afternoon, new meters installed near Grindavik by the Met Office detected elevated levels of sulfur dioxide, causing all of Grindavik to be evacuated again at short notice, just ahead of schedule.

The agency said in an update that although there are no other indications that the eruption has begun, this cannot be ruled out because gas does not appear unless magma is high in the Earth’s crust.

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