地質学：サントリーニ島で最近発生した地震は共通のマグマによって説明できるかもしれない

A more than 30-day earthquake episode that struck Greece in January 2025 could be explained by the volcanoes Santorini and Kolumbo sharing a magma chamber, according to a paper published in Nature. The findings are based on months of satellite observations measuring ground swelling, and could have implications for future natural disaster monitoring. After a swarm of earthquakes struck the island of Santorini in early 2025, Greek authorities declared a state of emergency. However, since then, there has been debate about whether this movement was related to volcanic activity.

Marius Isken, Jens Karstens and colleagues analysed this seismicity along with deformation data of Santorini and the surrounding area from months before and during the 2025 earthquake series. They found that Santorini and Kolumbo, located 7 kilometres away and underwater, likely share the same magma supply and could compete for it in times of high volcanic activity. More specifically, the deformation data revealed that when Santorini’s magma chamber filled, Kolumbo’s chamber deflated. Beginning in approximately July 2024 and through the months leading up to the earthquake episode, Santorini’s magma chamber was inflating at a depth of 3.8 kilometres, the authors estimated. After January 27, they observed the transfer of magma from 7.6 kilometres below Kolumbo to Santorini, which likely resulted in the earthquake swarm.

The authors note that such a shared magma mechanism has also been proposed in volcanoes in Hawaii, Iceland, and Kamchatka, and note that monitoring of these complex magma plumbing systems is crucial for anticipating future natural disasters.