The Reykjaness volcano system is a geological curiosity, with no central volcano to speak of. Instead, it boasts a captivating landscape of sinkholes, lava fields, slag craters, and pyroclastic cones. Notably, the crater known as Karl emerges from the sea, a remnant of the volcanic activity that characterized the Reykjaneseld eruptions in the 13th century. This fascinating feature reminds us of the past tumult of nature. Photo: Oddur Sigurðsson/Meteorological Office of Iceland.
- Up to 600 earthquakes detected so far
- Multiple seismic swarms have occurred in the area since 2021
- Future activity may continue with sporadic intensity
- No clear evidence of ground deformation detected in the region
Yesterday, March 12, 2025, at approximately 14:30, an intense earthquake swarm commenced off the coast of Reykjanestá. The initial hours were particularly frenetic, with around 50 to 60 earthquakes recorded shortly after the swarm began. As the day unfolded, the activity ebbed, only to crescendo again just before midnight, leading to a significant earthquake measuring 3.5 on the Richter scale. Notably, as the seismic activity fluctuated in the evening, it shifted slightly westward, represented on the accompanying map, where blue circles mark the early swarm locations and yellow to red circles indicate the later quakes.
To date, almost 600 earthquakes have been registered, including six exceeding a magnitude of 3. Residents from nearby areas, such as Grindavík—situated about 12 kilometers east of the epicenter—reported feeling some tremors. The swarm’s unpredictable nature has been evident, with intermittent lulls followed by sudden surges of activity. Since the beginning of 2023, five earthquake swarms have struck this same area, building on the notable seismic activity recorded in 2021 and 2022. These tremors are likely related to shifts in the stress field on the Reykjanes Peninsula, likely compounded by recent magmatic activity. However, recent deformation data show no clear signs suggesting that the current seismic events are due to underground magma movement.
As always, scientists at the Icelandic Meteorological Office are diligently monitoring the situation. They are leveraging all available data from sensors and measurements in and around Reykjanesstá to better understand the underlying causes of this latest earthquake swarm.
Data from Skjálfta-Lísa, the Icelandic Met Office’s earthquake monitoring system. The map visualizes the locations of earthquakes since noon on March 12, highlighting two distinct clusters. The accompanying graph tracks the cumulative number of earthquakes since the swarm began, while the top right graph details the magnitudes of these quakes. Darker colors indicate reviewed magnitudes, while lighter shades represent automatic readings. The bar chart on the right depicts hourly earthquake counts since noon yesterday.
