2025/08/13
Reykjanes: A Rift Between Two Worlds
The Reykjanes Peninsula in southwest Iceland looks quiet from a distance. Low hills roll toward the ocean. Small fishing towns cling to the coast. But beneath the surface, two of the Earth’s great plates, the North American and the Eurasian, are pulling apart. This slow stretch opens cracks in the crust, letting molten rock rise from deep below. When it reaches the surface, it pours out in long sheets rather than exploding in tall ash plumes.
For almost 800 years, this part of Iceland was quiet. Then, in 2021, the ground split open again, and what followed was not one isolated eruption but a sequence of events that continues into 2025. Scientists believe this is the start of a new active period that could last for decades.
Why Reykjanes Woke Up in Bursts
Reykjanes sits on the Mid-Atlantic Ridge, a giant underwater mountain range that runs through the Atlantic Ocean. Here, magma rises to form new crust as the plates pull apart. Most of this ridge is deep underwater, but in Iceland, it surfaces, cutting straight through the island.
Eruptions in Iceland usually happen in bursts separated by centuries of calm. When an eruption cycle starts, it can repeat over several decades. These events are called “fissure eruptions” because they tend to open as long cracks, sometimes stretching for miles. Lava flows can be fast-moving but generally low in explosive ash.
An aerial perspective of an active volcanic crater on Iceland’s Reykjanes Peninsula, where molten lava seeps from the vent and winds through the stark, blackened landscape.
A New Timeline of Eruptions: 2021 to 2025
The current cycle began in March 2021, following weeks of earthquakes that shook the region. From that point, the Reykjanes Peninsula experienced multiple eruptions, each with its own distinct character. Here’s a clear look at the eruptions so far:
March 19–September 18, 2021: Fagradalsfjall Awakens
In March 2021, after over a month of constant tremors, the first fissure opened in the Geldingadalir valley, part of the Fagradalsfjall volcanic system. The eruption began slowly, with lava bubbling from a small vent. Over time, it built towering cones and lava spread into nearby valleys. This eruption was unusual in its length for Reykjanes, lasting about six months. It gave scientists a rare, prolonged look at how magma moves in this slice of Iceland.
The eruption was gentle enough to pose no danger to people or infrastructure, luring geologists and adventurous hikers. Visitors could stand safely within sight of glowing lava flows, watching the valley floor transform day by day until the eruption ended in September.
August 3-22, 2022: Meradalir Erupts
Less than a year later, another eruption began, this time in Meradalir, just east of the 2021 site. This event lasted around three weeks after the fissure opened in a barren lava field, and lava poured into the Meradalir valley. Local scientists noted that magma appeared to come from the same deep source as the previous eruption, suggesting the system was still primed.
The eruption was spectacular but brief, lasting just under three weeks. Its intense flows and towering lava fountains carved a new landscape.
July 10–August 5, 2023: Litli-Hrútur’s Summer of Fire
By 2023, it was clear the activity was not over. In July, a fissure opened near Litli-Hrútur, north of the earlier sites. The eruption produced tall lava fountains and fast flows. For scientists, it was another sign that magma was finding new pathways under the peninsula. For visitors, it served as a reminder that conditions could change quickly, as this eruption began with little warning and ended after less than a month.
Thousands of visitors braved the long trek and came to witness the molten spectacle. For geologists, Litli-Hrútur was proof that eruptions in the region could quickly escalate in size and power.
Video: Lava engulfs houses in the town of Grindavík
December 18-21, 2023: Sundhnukagigar Spews
In late 2023, seismic swarms and ground deformation indicated that something significant was brewing near Grindavík, a small coastal town. On December 18, a fissure opened north of town and lava flows threatened roads and infrastructure.
It was the most powerful eruption in recent years, with lava flows ten times stronger than earlier events. Fortunately, the molten rock flowed away from the town, but not before covering 3.7 square kilometers of land.
Lava from a Reykjanes Peninsula eruption engulfs the edge of Grindavík, destroying several homes and leaving a stark black scar across the Icelandic landscape.
January 14 –15, 2024: The Hagafell Eruption
The Sundhnukagigar eruption in December paused after only a few days, but in January 2024, another fissure eruption began in the same area. This time, lava reached the edge of Grindavík, damaging homes and forcing evacuations. These events marked a dangerous turn as eruptions were now breaking out closer to populated areas.
February 8-10, 2024: Sundhnukagigar Strikes Again
In February, a 3-kilometer fissure erupted further north at Sundhnukagigar. The lava destroyed a hot-water pipeline, cutting off heating for four days during the coldest part of the year. This eruption stood out for producing black ash and steam, a likely sign of groundwater interaction with magma.
March 16–May 9, 2024: Hagafell
By early 2024, pressure beneath the Sundhnúkur system was still high. In March, a fissure opened near Hagafell. Lava once again spread toward Grindavík, and scientists worked alongside civil protection teams to monitor gas emissions, which were high during this eruption. By late May, the activity had stopped, but the region remained unstable.
May 29 – June 22, 2024: Early Summer Lava
In late May, Sundhnukagigar erupted yet again, this time starting with a 1-kilometer fissure that expanded to 3.4 kilometers. Lava fountains reached 50 meters high, and the eruption persisted for nearly a month, painting yet another blackened swath across the peninsula.
Molten lava streams from an active crater on the Reykjanes Peninsula, carving a fiery path through the rugged volcanic landscape.
August 22 – September 5, 2024: The Military Training Ground Eruption
The August eruption began with a 4-kilometer fissure in an area once used as a United States military training ground, raising concerns about unexploded ordnance. While the lava initially advanced rapidly, it was contained without significant damage to infrastructure. The eruption ended in early September.
November 20 – December 8, 2024: The Surprise Eruption
This event defied predictions as no large earthquake swarm preceded it; only subtle shifts in pressure readings were detected at the Svartsengi power plant. Just before midnight on November 20, a 3-kilometer-long fissure opened and released lava for over two weeks.
April 1, 2025: April Fool’s Day Eruption
Short, sharp, and unexpected, this eruption lasted only seven hours. Its timing gave it a memorable nickname, but its brevity didn’t diminish the fact that Reykjanes remained in a hyperactive state.
Panoramic aerial view of the 2023 Litli-Hrútur eruption in Iceland, where fiery lava fountains and glowing rivers of molten rock transform the Reykjanes Peninsula’s rugged terrain.
July 16-August 5, 2025: The Litla Skógfell Event
On July 16, 2025, another eruption began in the Sundhnúkur area, producing long lava flows and strong gas emissions once again, until it ended on August 5. Each of these events added to the growing understanding that the Reykjanes cycle was now fully active.
What the Reykjanes Eruptions Show Us
Looking at the sequence of eruptions, several patterns stand out to observers. The eruptions have been relatively small in volume compared to major Icelandic events, but their frequency is high. Magma appears to be moving along interconnected fissure systems, shifting location from year to year. Some eruptions start within hours of intense earthquake swarms, giving little lead time.
For scientists, this is a valuable chance to study how rift-driven eruptions evolve in real time. GPS and satellite data track how the ground swells as magma pushes upward. Gas sensors reveal changes in emission levels before and after eruptions. Each event adds another piece to the puzzle.
How Reykjanes Compares to Other Rift Zones
Other rift zones around the world share some similarities. The East African Rift, for example, also produces fissure eruptions, though its volcanic systems are spread over a much wider area. The Red Sea Rift, like the Mid-Atlantic Ridge, is mostly underwater, but it has produced eruptions on land in places such as Eritrea in Africa. Iceland is unique because the ridge runs across a populated island, making its rift eruptions more visible and more hazardous to people.
Visiting Eruption Sites and Staying Safe
While the Reykjanes eruptions have drawn many visitors, they carry real risks. Fresh lava fields remain hot for months. Gas emissions, especially sulfur dioxide, can reach dangerous levels, even far from the vent. Cracks in the ground can open without warning. And eruptions can start quickly after only brief signs of unrest.
Iceland’s Civil Protection and the Icelandic Meteorological Office post updates on activity, hazards, and access restrictions. Visitors should follow those notices closely. Even from safe distances, the view can be impressive; there’s no need to get close to the vents to experience the power of the eruptions.
Reykjanes peninsula: Looking Ahead
The 2021–2025 eruptions are almost certainly not the end of the story. If past cycles are any indication, the Reykjanes Peninsula may continue to see eruptions for decades. These could happen in the same areas as recent events or shift to other volcanic systems along the peninsula. For scientists, it’s a rare chance to watch the start of a rift cycle unfold. For Icelanders, it’s a reminder of the island’s restless foundations. The Reykjanes Peninsula, sitting between two worlds, will likely keep making history for years to come.
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