Iceland has been experiencing a historic series of volcanic eruptions on the Reykjanes Peninsula in the country’s southwest, beginning in December 2023 and continuing into 2025. The eruptions have forced the evacuation of an entire town, threatened critical energy infrastructure, and created ongoing hazards from lava flows and toxic gas. The most recent eruption occurred on April 1, 2025, near the Sundhnúkur crater row, though it lasted only about seven hours and produced the smallest lava volume of the entire series.
A Volcanic Series Unlike Anything in Modern Memory
The Reykjanes Peninsula had been volcanically quiet for roughly 800 years before activity resumed in 2021 near Fagradalsfjall. What followed was a dramatic escalation. Starting in December 2023, a rapid-fire sequence of eruptions began along the Sundhnúkur crater row, a fissure system located between two ridges called Stóra-Skógfell and Sýlingarfell. These eruptions have varied widely in size. The first event produced a dike (a wall of magma forced through rock) estimated at 15 kilometers long and containing up to 133 million cubic meters of material. By contrast, the April 2025 eruption produced just 0.4 million cubic meters of lava, roughly one-sixth the volume of the second-smallest eruption in the series.
What makes this sequence unusual is the repeating cycle of inflation and deflation. Magma accumulates in a reservoir near Svartsengi at about 4 to 5 kilometers depth, right around the boundary where rock transitions from brittle to ductile. Scientists measuring ground deformation with GPS and satellite radar have calculated that magma flows into this reservoir at rates between 2.4 and 9 cubic meters per second. The ground visibly rises as the chamber fills, then drops sharply when magma breaks through to the surface in an eruption. This cycle has repeated multiple times since late 2023, and there’s no indication it has stopped.
Grindavík: The Town That May Never Recover
The eruptions have hit the fishing town of Grindavík hardest. On November 10, 2023, Icelandic authorities ordered the evacuation of all approximately 3,800 residents after an alarming surge of earthquakes and evidence that magma was moving directly beneath the town. In January 2024, lava broke through two fissures and destroyed three homes outright. Several more were severely damaged by the seismic activity itself, with foundations cracked and structures destabilized.
Residents were scattered across the country with no return date. As of early 2024, authorities could not confirm whether Grindavík would ever be safe to inhabit again. The government erected protective barriers to try to redirect lava away from both the town and the nearby Svartsengi geothermal power plant, which supplies hot water and electricity to the region. The situation left thousands of people in limbo, owning homes they could not live in and facing deep uncertainty about their community’s future.
Air Quality and Gas Pollution
Volcanic eruptions release sulfur dioxide, a gas that irritates the lungs and can drift far from the eruption site. Icelandic health authorities set exposure limits at 350 micrograms per cubic meter for short periods (minutes to hours) and 125 micrograms per cubic meter for exposures lasting a day or more. When concentrations climb above 600 micrograms, vulnerable people and those with lung conditions can develop coughing. At levels above 2,600 micrograms, virtually everyone experiences respiratory irritation, coughing, and headaches.
Gas pollution advisories have been issued to the greater Reykjavík capital area during eruption events, particularly when wind patterns push volcanic plumes northwest toward populated zones. The eruptions also produce Pele’s hair, thin strands of volcanic glass that can travel many miles downwind. These fibers pose a hazard to both human lungs and aircraft engines. Authorities have noted that the prolonged seismic activity and air quality concerns have taken a psychological toll on residents across the region, with many reporting ongoing anxiety.
Impact on Flights and Travel
Unlike the 2010 Eyjafjallajökull eruption, which shut down European airspace for days, the Reykjanes eruptions have not caused widespread international flight cancellations. The eruptions occur relatively close to Keflavík International Airport, Iceland’s main hub, but they have been managed through localized restrictions rather than broad closures. A restricted airspace zone called BIR4 was established around the volcanic activity, with altitude limits between 1,500 and 2,500 feet. Above that zone sits Keflavík’s approach corridor, and below it, authorities have designated space for scientific drone operations.
Pilots flying near the area must carry transponders and monitor a specific radio frequency. They are warned about turbulence from the heat of lava fields, the possibility of volcanic ash and sulfur dioxide in the air, and the risk of Pele’s hair damaging engines. While individual flights have been rerouted and some temporary disruptions have occurred, the scenario feared after 2010, where ash clouds ground all European aviation, has not materialized from these eruptions.
Current Alert Status
The Icelandic Meteorological Office uses a four-tier color-coded system for volcanic alerts. Level 0 (green) means the system is at equilibrium. Level 1 and Level 2 (yellow) indicate conditions diverging from normal background levels, with Level 2 reflecting an acceleration in warning signs. Level 3 (red) signals an imminent or ongoing eruption. As of the latest available data, the Reykjanes system sits at a yellow alert condition, meaning activity remains above baseline even between eruptions.
Seismic monitoring captures thousands of earthquakes per month on the peninsula. In November 2024, around 1,900 earthquakes were detected, which was actually below the six-month average of 3,400 per month. That baseline gives a sense of how active the region has become. Each new inflation cycle at Svartsengi raises the question of when, not whether, the next eruption will occur. The pattern of repeated magma intrusions and eruptions along the Sundhnúkur crater row shows no signs of winding down, and scientists continue to monitor ground deformation in real time to provide warning before the next event.