Temporal linkages of explosive activity of Kolumbo and Santorini Volcanoes (Greece)

Abstract The histories of submarine explosive volcanoes are commonly poorly known due to inaccessibility of their eruptive archives. This raises uncertainties in the eruption frequencies of these highly hazardous systems, and in their interactions with neighboring volcanoes. The submarine Kolumbo Volcanic Chain (KVC) northeast of Santorini is made up of the polygenetic Kolumbo Volcano and a linear zone of more than 20 smaller volcanic cones and is one of the most active eruptive centers on the South Aegean Volcanic Arc. However, despite the destructive eruption of Kolumbo in 1650 CE, and unrest in 2024–2025, the eruptive history of the KVC is poorly known. International Ocean Discovery Program (IODP) Expedition 398 deep-drilled the seafloor at two sites on the western flank of Kolumbo. Here, we use tephrostratigraphy to identify 19 explosive eruptions of the KVC (probably mostly Kolumbo itself) ranging from basaltic andesite to rhyolite in composition and beginning at ca. 265 ka. The lifespan-averaged recurrence time of explosive activity along the KVC is ~6 k.y. (but as low as ~1 k.y. between 178 ka and 164 ka), although many of these eruptions were smaller than that of 1650 CE. The birth of Kolumbo coincided with the transition of Santorini to highly explosive activity, possibly due to joint interactions with regional lithospheric stresses. Moreover, the three main phases of edifice construction at Kolumbo (ca. 265–193 ka, 24 ka, and 0.4 ka) broadly correspond to periods of caldera-forming eruptions at Santorini, reflecting additional couplings between the two volcanic systems on shorter time scales.