Svartsengi

In December 2023, a new sequence of eruptions began on the Reykjanes Peninsula in southwestern Iceland. Svartsengi, a volcanic system dormant for 783 years, returned to activity on December 18, 2023 with a short-lived but powerful effusive eruption. That event marked the start of multiple episodes that threatened nearby infrastructure: the Svartsengi geothermal power plant, the Blue Lagoon spa and resort, and the town of Grindavík. Grindavík was first evacuated on November 10, 2023 after an intense seismic swarm. In late November, authorities began building earthen barriers to protect the power-plant area; after the first eruption, additional barriers were raised around Grindavík to reduce the risk of lava entering the town. These measures have so far proved effective. At the same time, lava repeatedly overran roads in the area, which were rebuilt within days after each event. By August 2025, the volcano had produced nine separate eruptive episodes from the Sundhnúkagígar crater row, following broadly similar patterns. Activity typically begins abruptly along a 2–6 km fissure with very high effusion rates, estimated between 1,000 and 2,500 cubic meters of lava per second (as observed in August 2024). This initial phase lasts a few hours before dropping markedly. The first three episodes (December 2023, and January and February 2024) lasted one to three days; the next six continued at lower rates for at least several weeks, the longest lasting nearly two months, from March 16 to May 9. This sequence will likely continue. Monitoring data indicate a steady inflow of magma into a small reservoir located roughly 5 km beneath the area. The eruptions have drawn significant international attention, both in the media and the scientific community. The lava-diversion works may help mitigate future impacts on populated areas. Meanwhile, the setting, straddling the boundary between the North American and Eurasian Plates, offers invaluable data for understanding volcanism in this type of tectonic environment.