An intense swarm of earthquakes around Greece’s Santorini Island in January has revealed a fiery underground link between two neighboring and historically explosive volcanoes.

Analyses of seismic activity from June 2024 through February 2025, along with changes in the island’s surface elevation, suggest that the same well of magma feeding the Santorini volcano may also supply the submerged Kolumbo volcano, just seven kilometers away, researchers report September 24 in Nature.