“An eruption has started near Sundhnuksgigar, north of Grindavik,” the Icelandic Meteorological Office (IMO) said in a statement, almost three weeks after the end of a previous eruption that had been ongoing since March 16.

“The eruption plumes reach a height of at least 50m,” it added.

The nearby Blue Lagoon geothermal spa, Iceland’s biggest tourist attraction, said it had also evacuated its facilities today.

The eruption was the fifth to occur on the peninsula since December.

The IMO had reported “intense earthquake activity” prior to today’s eruption.

In addition, it had reported the accumulation of 20 million cubic metres of magma in the magma chamber below Svartsengi, where a power plant that supplies electricity and water to around 30,000 people on the peninsula is located.

The Svartsengi plant was evacuated and has largely been run remotely since the first eruption in the region in December, and barriers have been built to protect it.

Most of the 4,000 residents of the nearby town of Grindavik were permanently evacuated in November, prior to the eruptions in December, January, February and March.

Lava flowed into the streets of Grindavik during the January eruption, engulfing three homes.

But a few die-hard residents had returned to live in neighbourhoods less at risk from lava flow.

On Monday evening, the Met Office had said that “about 400 earthquakes” had been measured in the past seven days near the Sundhnuksgigar crater row.

Until March 2021, the Reykjanes peninsula had not experienced an eruption for eight centuries.

Volcanologists now believe a new era of seismic activity has begun in the region.