Iceland declared a state of emergency on Friday after a series of powerful earthquakes rocked the country's southwestern Reykjanes peninsula, in what could be a precursor to a volcanic eruption.
"The National police chief ... declares a state of emergency for civil defence due to the intense earthquake (activity) at Sundhnjukagigar, north of Grindavik," the Department of Civil Protection and Emergency Management said in a statement.
"Earthquakes can become larger than those that have occurred and this series of events could lead to an eruption," the administration warned.
The Icelandic Met Office (IMO) said an eruption could take place "in several days".
The village of Grindavik, home to around 4,000 people, is located some three kilometres (1.86 miles) southwest of the area where Friday's earthquake swarm was registered.
It has evacuation plans in place in case of an eruption.
Around 1730 GMT, two strong earthquakes were felt as far away as the capital Reykjavik some 40 kilometres away, and along much of the country's southern coast, rattling windows and household objects.
According to preliminary IMO figures, the biggest tremor had a magnitude of 5.2, north of Grindavik.
Police closed a road running north-south to Grindavik on Friday after it was damaged by the tremors.
Some 24,000 tremors have been registered on the peninsula since late October, according to the IMO, with "a dense swarm" of nearly 800 quakes registered between midnight and 1400 GMT Friday.
The IMO noted an accumulation of magma underground at a depth of about five kilometres (3.1 miles). Should it start moving towards the surface it could lead to a volcanic eruption.
"The most likely scenario is that it will take several days rather than hours for magma to reach the surface," it said.
"If a fissure were to appear where the seismic activity is at its highest now, lava would flow to the southeast and to the west, but not towards Grindavik."
New active era
Nonetheless, the Department of Civil Protection said it was sending the patrol vessel Thor to Grindavik "for security purposes".
Emergency shelters and help centres were to open in Grindavik later Friday, as well as three other locations in southern Iceland, for information purposes and to assist people on the move.
On Thursday, the Blue Lagoon, a popular tourist destination located near Grindavik famed for its geothermal spas and luxury hotels, closed as a precaution following another earthquake swarm.
Also nearby is the Svartsengi geothermal plant, the main supplier of electricity and water to 30,000 residents on the Reykjanes peninsula.
It has contingency plans in place to protect the plant and its workers in the event of an eruption.
Since 2021, three eruptions have taken place on the Reykjanes peninsula, in March 2021, August 2022 and July 2023.
Those three were located far from any infrastructure or populated areas.
Iceland has 33 active volcanic systems, the highest number in Europe.
The North Atlantic island straddles the Mid-Atlantic Ridge, a crack in the ocean floor separating the Eurasian and North American tectonic plates.
Prior to the March 2021 eruption in an uninhabited area around Mount Fagradalsfjall, the Reykjanes volcanic system had remained dormant for eight centuries.
Volcanologists believe the new cycle of increased activity could last for several decades or centuries.
An April 2010 massive eruption at another Iceland volcano, the Eyjafjallajokull in the south of the island, forced the cancellation of some 100,000 flights, leaving more than 10 million travellers stranded.
