2023–2024 Sundhnúkur eruptions

The 2023–2024 Sundhnúkur eruptions are an ongoing series of volcanic eruptions in the Reykjanes peninsula, near the town of Grindavík, Iceland. As of 16 March 2024, there have been four eruptions between December 2023 and March 2024, following an intense series of earthquakes. Although localised, the seismic and volcanic activity have caused significant disruption across the western part of the peninsula.

The eruptions were preceded by an intense earthquake swarm in the Eldvörp–Svartsengi volcanic system that began on 24 October 2023, caused by a magmatic intrusion underneath the area. The frequency and intensity of the earthquakes dramatically increased on 10 November 2023, with 20,000 tremors recorded by that time, the largest of which exceeded magnitude 5.3. An evacuation was ordered in Grindavík, and large-scale subsidence in and around the town caused significant damage.

The first eruption started on the evening of 18 December 2023, at the Sundhnúkur crater row north of Grindavík, with lava spewing from fissures in the ground. The intensity of the eruption and accompanying seismic activity decreased early on 19 December, with lava seen spreading laterally from both sides of the newly opened fissures. The eruption was described as the largest in the Reykjanes Peninsula since the beginning of eruptive activity in 2021, with lava fountains, up to 100 metres (330 ft) high, and was visible as far away as the capital Reykjavík, 42 kilometres (26 mi) away. The eruption ended on 21 December, after the Icelandic Meteorological Office (IMO) said no lava was erupting after a flight over the volcano, but clarified that it was "too early to declare the eruption over".

On 14 January 2024, a second fissure erupted north of Grindavík with most of its lava steered away from the town by newly constructed protective barriers. A few hours later, a smaller third fissure opened less than 100 metres (330 ft) from the town inside the protection barriers, with its lava reaching and burning down three residential houses.

A third eruption began on 8 February 2024 about a kilometre (half a mile) north of Grindavík, in the same area as the December eruption, with a fissure about 3 kilometres (1.9 mi) long effusively erupting lava on top of earlier flows. It caused significant damage to infrastructure, leading to the declaration of a state of emergency.

A fourth eruption commenced on 16 March 2024, originating from a fissure approximately 3–4 kilometres (1.9–2.5 mi) in length. This event is considered more powerful than any preceding eruption on the peninsula since 2021, establishing it as the most significant in recent years. A magma intrusion previously occurred on 2 March but did not breach the surface, potentially delaying the onset of the current eruption. Given the timing between the last three eruptions, an eruption had been anticipated at the beginning of March. This eruption is still ongoing after more than a week and has proven to be longer-lasting than any observed since December.

One individual was reported missing after falling into a crevice resulting from seismic activity. The missing person report was filed by a work colleague who, upon returning to the site, discovered the individual's absence without any witnesses to the event. Despite extensive search efforts, no trace of the person was found before the search was officially called off two days later, due to the hazardous conditions faced by rescue workers.