Reconstructing Kolumbo’s explosive history: insights from 3D seismic data (Santorini)

Shallow marine volcanism can produce violent phreatomagmatic eruptions that pose a significant hazard to surrounding coastal communities. Kolumbo volcano, located 7 km northeast of Santorini, is one of the most hazardous volcanic centers in the Aegean Sea. Kolumbo last erupted explosively in 1650, causing over 70 casualties and forming the 2500 m wide and 500 m deep present-day crater. While 2D seismic reflection data have provided a general overview of its the temporal evolution, the full complexity of Kolumbo’s internal structure can only be reconstructed using three-dimensional (3D) data. Here, we use high-resolution 3D seismic reflection data covering most of Kolumbo’s edifice, and present a detailed reconstruction of its internal architecture and the processes that have controlled its evolution. We show that Kolumbo’s edifice was formed by more than the previously assumed five major explosive eruption.  Furthermore, we present evidence for at least one additional explosive eruption that formed a crater larger than the present-day crater from the 1650 eruption. Together, the increased explosive potential of past eruptions and the higher eruption frequency indicate a greater than was previously appreciated. Considering its proximity to Santorini, one of the most visited islands in the eastern Mediterranean, our results emphasise the need for more comprehensive natural hazard monitoring strategies at the central Aegean Sea.