Overview

• Researchers report more than 28,000 earthquakes struck from late January to March 2025, with the strongest exceeding magnitude 5.0.
• Roughly 300 million cubic meters of magma rose from the deep crust and settled about 4 kilometers beneath the seafloor, driving the swarm.
• Magma first intruded a shallow reservoir beneath Santorini in July 2024, lifting the island by a few centimeters before quakes migrated northeast in pulses from about 18 kilometers depth.
• GPS and InSAR data showed concurrent deflation at Santorini and Kolumbo, which the authors interpret as evidence of a hydraulic connection between the two volcanoes.
• The reconstruction combined an AI-based earthquake-location method with ocean-bottom sensors deployed at Kolumbo by the MULTI-MAREX project, and monitoring has since been intensified.