REYKJAVIK - An Icelandic volcano that erupted and spewed lava into the sky overnight near a power plant was less active on Tuesday, after weeks of intense seismic activity southwest of Reykjavik.
The eruption, only three kilometres from the evacuated fishing port of Grindavik on the Reykjanes peninsula, began Monday at around 10:17 pm (2217 GMT) after a "swarm" of small tremors, the Icelandic Meteorological Office (IMO) said.
The volcano opened a fissure in the ground about four kilometres long, with the southern end just three kilometres from Grindavik.
In an update on Tuesday at 1430 GMT, the IMO said the lava flow was "estimated to be about one-quarter of what it was at the beginning of the eruption on 18 December, and a third of the original fissure is active."
"The lava fountains are also lower than at the start of the eruption, reaching about 30 meters (98 feet) at their highest."
Amid weeks of warnings from scientists, the authorities built reinforcements around the Svartsengi geothermal plant, which is just two kilometres from the eruption.
It supplies electricity and water to 30,000 people on the peninsula.
Live-streamed footage of the eruption showed glowing orange jets of lava spewing from a gash in the ground, surrounded by billowing clouds of red smoke against the dark winter sky.
In December, the sun rises around 11:00 am in the area just south of the Arctic Circle, and sets around 3:00 pm.
For weeks, experts had been anticipating an eruption in the area some 40 kilometres from the capital Reykjavik, prompting the authorities to evacuate thousands of people.
The nearby Blue Lagoon geothermal spa, famed for its turquoise waters, is closed to visitors.
Vidir Reynisson, head of the Department of Civil Protection, urged people to stay away from the area, telling a local television station: "This is no tourist eruption."
The volcano, which has yet to be given a name, was located near the Sundhnukagigar crater row.
Unlike the major Icelandic eruption in 2010 that grounded thousands of flights across Europe and North America, this one did not create an ash plume. Reykjavik's international airport remained open Tuesday.
- New era -
Since October, thousands of earthquakes had been detected on the Reykjanes peninsula, a possible precursor to an impending volcanic eruption.
"Right now there is no immediate risk of infrastructure being threatened," Grindavik mayor Fannar Jonasson told the daily Morgunbladid on Tuesday.
Roughly 4,000 people were evacuated from Grindavik on November 11 after scientists said a tunnel of magma was shifting beneath them.
The series of small earthquakes -- sometimes hundreds per day -- had damaged roads and buildings, an AFP reporter in Grindavik said.
Authorities have organised occasional trips to the village since, allowing those with homes in the most perilous parts to rescue everything from cherished pets to photo albums, furniture and clothing.
Volcanic eruptions are not uncommon in Iceland, which is home to 33 active volcano systems, the highest number in Europe. But the Reykjanes peninsula had not experienced an eruption for eight centuries until 2021.
Since then, eruptions have struck in 2021, 2022 and earlier this year -- all in remote, uninhabited areas.
With no danger to infrastructure or lives, they drew large crowds of visitors.
Volcanologists say this could be the start of a new era of activity in the region.
Situated in the North Atlantic, Iceland straddles the Mid-Atlantic Ridge, a crack in the ocean floor separating the Eurasian and North American tectonic plates.
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By Jeremie Richard