Icelandic authorities were on Tuesday preparing to build defence walls around a geothermal power plant in the southwestern part of the country that they hope will protect it from lava flows amid concerns of an imminent volcanic eruption.
Seismic activity and underground lava flows intensified on the Reykjanes peninsula near the capital Reykjavik over the weekend.
Concern molten rock would rise to the surface of the earth within days prompted authorities to evacuate almost 4,000 from the fishing town of Grindavik on Saturday.
Located between the Eurasian and the North American tectonic plates, among the largest on the planet, Iceland is a seismic and volcanic hot spot as the two plates move in opposite directions.
Iceland's Justice Minister Gudrun Hafsteinsdottir told state broadcaster RUV that a large dike has been designed to protect the Svartsengi geothermal power plant, located just over six kilometers from Grindavik.
Equipment and materials that could fill 20,000 trucks were being moved to the plant, she said.
Construction of the protective dike around the power station was awaiting formal approval from the government. The plant produces hot and cold water and electricity for the Reykjanes peninsula.
A spokesperson for HS Orka, operator of the power plant, told Reuters that the plant supplies power to the entire country although a disruption would not impact the power supply to the capital Reykjavik.
Seismic activity in southwestern Iceland decreased in size and intensity on Monday, but the risk of a volcanic eruption remained significant, the Icelandic Meteorological Office said in a statement.
As of late Monday evening, the volcanic hazard assessment in and around Grindavik was unchanged from Sunday.
Almost all of the town's 3,800 inhabitants were briefly allowed back into the town on Monday to collect valuables, pets and livestock, the Icelandic department of civil protection and emergency management said in a statement, citing local police.
Most pets and farm animals had been rescued from Grindavik by Monday night, according to rescue charity Dyrfinna.