Earthquake swarm rattles Iceland as possible volcanic eruption looms

The Fagradalsfjall volcano is in Iceland’s southern peninsula region, about 25 miles southwest of Reykjavik, the country’s capital. A number of tremors have shaken the city, and the famed Blue Lagoon geothermal spa in Grindavik has been closed. It was initially unclear if Fagradalsfjall was responsible for the increased seismic activity or if an eruption was brewing elsewhere within the Reykjanes volcanic system.

A Code Orange — or a level 3 out of 4 on the universal ground-based volcano alerting scale — has been declared, raising concerns at Keflavik International Airport, which sits just northwest of the seismically active region.

The Icelandic Met Office wrote that the earthquakes were located about two miles northeast of Grindavik, with the fault slips occurring about two to three miles below the ground.

“The signs that can be seen now … are similar to those seen on the eve of the first eruption at Fagradalsfjall in 2021, and are very similar to the seismic activity that was measured about a month before that eruption,” the Met Office wrote.

What are supervolcanoes and should we really be worried about them?

In the most likely scenario, the office said, it will take several days for magma to reach the surface and an eruption to begin.

Still, the quaking has already ruptured roadways. It appears that up to three inches of uplift, or vertical movement of the ground, has occurred near the volcano.

A total of 295 earthquakes of magnitude 3.0 or greater have been detected in the past 72 hours, with upward of 90 percent of those occurring in the past day.

While Iceland is tectonically and volcanically active, the region around the Fagradalsfjall volcano had lain dormant for over 6,300 years until December 2019. That’s when a flurry of earthquakes, including two that reached magnitude 5.6, rattled the peninsula. Then on Feb. 4, 2021, a magnitude-5.7 earthquake caused minor damage to homes. Six weeks later, on March 19, the volcano erupted as a roughly 2,000-foot-long fissure started spewing lava.

The fissure was later named Geldingadalsgos, representing a possible new shield volcano — a broad volcano with gently sloping sides — and it attracted widespread tourism. Several other fissures opened in April, but only one remained active in May 2021. Another eruption from a separate fissure of Fagradalsfjall took place on Aug. 3, 2022.

Then this past summer, in early July, a new eruption began near Litli-Hrutur, also part of the Fagradalsfjall volcano. It was about 10 times as big as the first two eruptions. It diminished by Aug. 5.

Another eruption of that scale is likely in the broader Fagradalsfjall region on the Reykjanes Peninsula. Residents and travelers do not need to worry about a repeat of 2010, when an explosive eruption occurred at Eyjafjallajokull, in south-central Iceland. It ejected 330 million cubic yards of material and produced an ash cloud that rose nearly five miles high. Most of Europe’s airspace was closed to aviation between April 15 and April 20, 2010.