The risk of a potential volcano eruption in the Svartsengi volcanic system in Iceland has captured widespread attention since 10 November 2023. In response, authorities escalated the alert level to orange and evacuated almost 4000 people near the town of Grindavik. However, the threat has subsided in the recent weeks. On 6 December, the Icelandic Met Office (IMO, Iceland) reported that the magma inflow to the dike that formed on 10 November has likely ceased, significantly decreasing the risk of an eruption along the dike. It is likely that this sequence of events will repeat given the geology of the area. However, accurately predicting when this might happen remains uncertain, ranging from days to several months. The prospect of a volcanic eruption raised concerns about the potential for a volcano-generated tsunami. The Intergovernmental Coordination Group for the North Eastern Atlantic Mediterranean and connected seas Tsunami Early Warning and Mitigation System (ICG/NEAMTWS) continues to monitor the situation through its Tsunami Service Providers (TSPs) and expert networks. Mr Halldór Björnsson, Coordinator of Atmospheric Research at the IMO, emphasized that “if there is an eruption, it is not likely to extend into the sea, and the bottom topography poses no risk of submarine landslides, therefore, the risk of a tsunami in that area is extremely low”.
The area has experienced over 4000 earthquakes since 25 October 2023, with many surpassing magnitude 4, and the most potent events reaching magnitude 5. The main driving force behind these events is the spreading of the North American and Eurasian tectonic plates. These forces literally tear the ground apart as the plates move in opposite directions. The empty space between the plates is usually filled with magma rising from the Earth’s mantle. The most likely eruption scenario is a large lava flow, potentially accompanied by eruption cones extending over a greater distance. There is a minimal chance that this eruption would also produce an ash cloud.
COSMO-Skymed interferogram spanning 24-hours between 18−19 November 2023 at 06:41. The broad uplift signal visible in orange/red around Svartsengi is indicative of a deep inflation (>5 km) taking place. Source: Icelandic Meteorological Office.
Over the past millennium, Iceland has experienced eruptions approximately every 3 to 4 years on average. Recent eruptions show no evidence of tsunami occurrences. However, there are historically tsunami records possibly resulting from massive volcanic eruptions in 1362 CE and 1721 CE. The event of 1362 was triggered by an explosive eruption, while the one of 1721 was a subglacial eruption that led to an outburst flood. Mr Halldór Björnsson underlined that “the current situation is nothing like those past cases, as Iceland is likely anticipating an onshore effusive eruption. The same could be mentioned about the ongoing seismic activity, which is likely not going to cause a tsunami”.
Addressing the potential for a volcano-generated tsunami, Ms Angela Hibbert from the National Oceanography Centre (NOC, United Kingdom), added that “the eruption can result in phreatic explosions as a result of lava and water interactions, however, the waves produced would likely be small.”. The Emergency Response Coordination Centre (ERCC) of the European Commission is also closely following the situation with support of the “All Risk Integrated System TOwards Trans-boundary hoListic Early-warning (ARISTOTLE) Pilot Project”.
While the magma inflow to the dike near the town of Grindavik, formed on 10 November 2023, appears to have subsided, the possibility of magma propagation persists. Should propagation occur, it is likely to move from Svartsengi into the previously formed dike, making it the most probable area for an eruption. Therefore, continuous monitoring of the situation in the area is essential.
For more information on the evolution of the volcanic activity in the Svartsengi system and the town of Grindavik, Iceland, please visit the following link.