VolcanoA powerful swarm of nearly 4000 earthquakes in a 24-hour period on the Reykjanes Peninsula in Iceland has raised fears of an eruption, with a potentially severe impact on air traffic.

European weather monitoring site Severe Weather Europe reports that the current swarm is continuing “at a strong pace”, with tremor signals indicating the quakes are likely due to subterranean magma movement.

“This has prompted the officials to raise the alert level in the area,” the report added. “An eruption is likely, with the chance increasing steadily as the earthquake activity continues.”

Latest reports this morning say a fissure has opened and lava is flowing.

When the current earthquake swarm started rocking the peninsula on Saturday, Icelandic authorities declared an “uncertainty phase”, lifting the aviation alert colour code from green to yellow. The code was raised again last night to orange, defined as “Volcano is exhibiting heightened unrest with increased likelihood of eruption. or, Volcanic eruption is underway with no or minor ash emission”.

The next level up in the colour code is the maximum, red, signifying: “Eruption is forecast to be imminent with significant emission of ash into the atmosphere likely. or, Eruption is underway with significant emission of ash into the atmosphere.”

When Iceland’s Eyjafjallajokull volcano erupted in 2010, it produced a vast ash cloud that severely disrupted European airspace and led to passenger delays, with the effects feeding around the world.

Keflavík International Airport, the major point of entry for Iceland, is located on Reykjanes Peninsula, which only recently rattled into volcanic life. After nearly 800 years of inactivity, volcanic unrest began on the peninsula in 2020. When the Fagradalsfjall volcano on the peninsula began erupting on 19 March 2021, National Geographic’s experts predicted it “may mark the start of decades of volcanic activity”.

Iceland Review quoted Einar Hjörleifsson at the country’s meteorological office, an expert in natural hazards, saying that the first large earthquake in the locality occurred at a depth of 5-7 kilometres.

“He said the increasing magnitude of the eruptions may indicate that some significant seismic event is afoot; the activity may be a precursor to another volcanic eruption,” Icelandic Review said.

Iceland, one of the world’s most active volcanic regions, experiences frequent earthquake activity because it sits on the Mid-Atlantic Ridge – the boundary between the Eurasian and North American tectonic plates.

Reykjanes Peninsula’s large lava fields allow little vegetation. Numerous hot springs dot its southern half.

The country experiences a volcanic eruption of varying magnitude every four to six years on average.

Written by Peter Needham