800 years of quiet
Prior to 2021, it had been almost 800 years since a volcanic eruption had occurred on the Reykjanes peninsula in Southwest Iceland. Between 1211 and 1240, a series of eruptions, referred to as the Reykjanes Fires, took place during a heightened period of volcanic activity that began around 950.
2021 Fagradalsfjall eruption
At the end of February 2021, however, something was stirring on the Reykjanes peninsula. A swarm of earthquakes shook the region for approximately three weeks, culminating in an eruption that began on March 19, 2021.
The eruption turned out to be a long one, Iceland’s fourth-longest eruption in the 20th and 21st centuries. Fortunately, it was neither especially powerful nor threatening to infrastructure.
Like the eruption in Eyjafjallajökull in 2010, which has been widely credited with starting Iceland’s tourism boom, the Fagradalsfjall eruption (also known as the Geldingadalir eruption) attracted thousands of visitors, local and foreign alike.
It lasted from March 19 to September 18, just under six months.
Experts held that it likely marked the beginning of an active volcanic period on Reykjanes; geologic activity on the peninsula is characterised by volcanic periods lasting around 300 years alternating with seismic periods lasting 600-800 years.
2022 Meradalir eruption
Less than a year later, on August 3, 2022, another eruption began on the Reykjanes peninsula when a fissure, approximately 300 metres [982 feet] long, opened in the northern part of Meradalir valley, not far from Fagradalsfjall.
Like the 2021 eruption, the Meradalir eruption was preceded by weeks of earthquakes. The eruption lasted approximately 18 days, with the amount of resulting lava totalling ca. 8% of the volume and a quarter of the area of the Fagradalsfjall eruption in 2021.
2023 Litli-Hrútur eruption
The third eruption on the Reykjanes peninsula in the modern era began on the afternoon of July 10, 2023, at Mt. Litli-Hrútur, situated between the mountains Keilir and Fagradalsfjall.
The eruption at Litli-Hrútur involved significant gas pollution, which led to the authorities closing access to the eruption site. Lava from the eruption also caused major wildfires – the most extensive moss fires on record in Iceland – and the area was closed once again. The volcanic ash cloud from the eruption reached all the way to the Westfjords.
By early August, lava production had significantly decreased, and geologists concluded that the end of the eruption was near. By August 5, activity in the crater had ceased.
2023-2024: The fires of Sundhnúkagígar
Starting at midnight, October 25, 2023, the Reykjanes peninsula experienced a swarm of relatively minor earthquakes, concentrated in the area around the town of Grindavík, a small fishing town on the southern coast of the peninsula home to approximately 3,600 people. Land uplift, an indicator of magma intrusion, had begun again – not three months after the conclusion of the eruption at Litli-Hrútur.
Following days of continued tremors and land uplift, a 4.2 magnitude earthquake struck the area just west of the Blue Lagoon. The Department of Civil Protection and Emergency Management declared an Uncertainty Phase; magma intrusion was occurring worryingly close to the Blue Lagoon and the Svartsengi Geothermal Power Plant, which supplies Reykjanes residents with water and electricity.
On November 10, following a day of intense seismic activity, the authorities put a mandatory evacuation notice into effect for Grindavík and emergency relief centres were opened in the capital area to temporarily accommodate residents. It was the first time that an Icelandic town had been fully evacuated due to a volcanic threat since an eruption in the Westman Islands in 1973. The seismic activity on November 10 caused significant damage to infrastructure and homes in Grindavík, and many crevasses opened in and around the town.
As geological activity died down, residents were slowly allowed back into town to retrieve valuables. The evacuation order was extended and the government scrambled to find temporary housing for Grindavík residents elsewhere.
Three houses destroyed by the lava
By December, with no signs of an imminent eruption, many Grindavík residents had grown impatient and expressed the desire to return to their homes; the Blue Lagoon had been reopened, and businesses had been allowed to operate in Grindavík during the daytime.
On December 18, however, without much notice, an eruption began near Mt. Sýlingarfell, 3 km [1.9 mi] away from Grindavík. It began much more powerfully than the previous three eruptions in the same area and produced more lava in its first seven hours than all of the lava produced by the Litli-Hrútur eruption. It lasted only three days.
Not long after that eruption had concluded, land uplift had begun again. On January 10, a man fell into a crevasse in Grindavík, which he had been working to fill; despite extensive search efforts, his body has not been recovered. The accident prompted the authorities to reevaluate the hazard levels in Grindavík. Another mandatory evacuation was imposed for January 15. Following intense seismic activity, Grindavík was evacuated two days ahead of schedule, on January 13.
On the morning of January 14, another eruption occurred, much closer to Grindavík than the previous eruption. A fissure opened on both sides of a recently erected protective barrier on the north side of the town. Four hours after the eruption began, a second fissure opened even closer to town, and lava from that fissure eventually destroyed three houses on the edge of Grindavík.
Not even four weeks after the last eruption, the third volcanic eruption on the Reykjanes peninsula within the last three months began. In the early morning of February 8, a fissure opened near Sundhnúk, in close proximity to the location of the December eruption. After just a day, the eruption subsided and has ended for now. Experts are predicting more eruptions to follow, anticipating cyclical patterns of intense but brief activity, potentially altering if magma gathers in the Eldvörp craters. In the event that magma would begin accumulating in Eldvörp — a series of craters approximately ten kilometres long, where lava flowed during the Reykjanes Fires between 1210 and 1240 — this pattern would, however, likely change; the eruptions would become larger and last longer.
Uncertainty for Grindavík residents
Since the eruption on January 14, land uplift has been ongoing. At the time of writing, Grindavík residents, most of whom had been living in temporary housing outside the town, partly subsidised by the government, have faced increased uncertainty. During an emotional town hall in January, many residents called on the government to buy out their properties in Grindavík so that residents who wish to settle elsewhere have the financial means to do so.
The government is currently drafting legislation on long-term support measures for Grindavík residents, to be introduced in early February. The Reykjanes peninsula will likely see more eruptions in the coming years and it is unclear how they might impact the town of Grindavík or the surrounding area.
