Santorini's Unsettling Seismic Saga: A Tale of 21,000 Quakes and No Eruption
In a gripping presentation at the National Observatory of Athens, Greek scientists unveiled their findings on the 2025 Santorini-Amorgos seismo-volcanic crisis, leaving us with more questions than answers. With Climate Crisis and Civil Protection Minister Giannis Kefalogiannis in attendance, the event titled "The Seismo-Volcanic Crisis of Santorini: One Year After - Results and Conclusions" shed light on the conclusions of Greece's permanent scientific committees on seismic risk and the monitoring of the Hellenic Volcanic Arc.
Dr. Vassilis Karastathis, director of the Athens Geodynamic Institute, described the 2025 activity as an extraordinary earthquake swarm, an extremely rare occurrence due to the sheer number of quakes and the short timeframe. He revealed that while most events had a tectonic origin, a significant portion indicated the intrusion of magmatic fluids, creating a unique "tectono-magmatic" sequence.
The statistics are staggering: scientists recorded over 21,000 earthquakes between January 26 and June 30, 2025, with an astonishing 19,523 of them occurring in the first quarter alone. Karastathis highlighted that the island experienced 216 earthquakes above magnitude 4 between February 2 and 12 - a figure that dwarfs comparable national records from 2023 and 2024.
Experts linked this crisis to a period of volcanic unrest between August 2024 and January 2025, although they emphasized that this earlier phase was significantly weaker than the 2011-2012 episode. Karastathis explained that the crisis produced an immense workload due to the exceptionally high frequency of earthquakes, with automated epicentre systems struggling to keep up due to overlapping signals. Analysts had to apply stricter criteria and conduct enhanced manual checks, resulting in a comprehensive analysis completed in the summer of 2025 and presented at a global conference in Lisbon.
The final processing produced updated epicentre maps utilizing new seismic velocity models and data from a distributed acoustic sensing (DAS) system. The analysis revealed seismicity depths ranging from 5 to 15 kilometres, with no evidence of magma rising close to the surface. Scientists linked the epicentres to known tectonic structures, suggesting that magmatic fluids had penetrated existing faults.
Karastathis further clarified that 70 to 76 per cent of the earthquake mechanisms were tectonic in nature, while the remaining showed magmatic characteristics. Importantly, researchers detected no seismic signals or background "noise" associated with an imminent eruption or the formation of a new volcano. This led scientists to conclude that the 2025 crisis involved deep magmatic intrusion without any immediate volcanic danger.
Efthymis Lekkas, president of the Earthquake Planning and Protection Organisation (OASP), described the response as a real-time crisis exercise, praising the cooperation between scientists and Civil Protection. He emphasized the global uniqueness of the Santorini phenomenon and the importance of managing landslide risks within the caldera.
Kostas Papazachos, seismology professor and president of IMBIS, highlighted the long-term monitoring of the volcano and the active role of scientific observation in supporting decision-making during crises. He noted that authorities had strengthened monitoring infrastructure with permanent stations on Santorini, Thirasia, and Nea Kameni.
Assistant professor Vassilis Sakkas presented geodetic measurements revealing intense ground deformation within the caldera. He reported uplift of up to 60 millimetres and horizontal displacement of 70 millimetres. During January and February 2025, scientists observed seismicity migrating towards the Anydros area at a rapid pace of 4 to 5 kilometres per day, while Imerovigli experienced subsidence of up to 80 centimetres per year.
Sakkas noted that while deformation rates decreased from March 2025, Santorini continued to show uplift. He emphasized the need for continuous geodetic, seismological, and geophysical monitoring to enhance our understanding and forecasting capabilities.
In his closing remarks, Dr Sp. Vasilakos, director and board president of the National Observatory of Athens, declared that this meeting marked a new era for the Observatory and the Geodynamic Institute. He expressed the hope that the dialogue would strengthen public services and improve Greece's preparedness for future crises.
But here's where it gets controversial: with all these seismic events, why hasn't there been an eruption? And what does this mean for the future of Santorini? These are questions that scientists and experts are still grappling with, leaving us with a sense of intrigue and a desire to learn more. What are your thoughts on this seismic saga? Feel free to share your insights and opinions in the comments below!
