The Christiana-Santorini-Kolumbo volcanic field (CSKVF) in the Aegean Sea is one of the most active volcano-tectonic lineaments in Europe. Santorini has been an iconic site in volcanology and archaeology since the 19th century, and the onshore volcanic products of Santorini are one of the best-studied volcanic sequences worldwide. However, little is known about the chronology of volcanic activity of the adjacent submarine Kolumbo volcano, and even less is known about the Christiana volcanic island. In this study, we exploit a dense array of high-resolution marine seismic reflection profiles to link the marine stratigraphy to onshore volcanic sequences and present the first consistent chronological framework for the CSKVF, enabling a detailed reconstruction of the evolution of the volcanic rift system in time and space. We identify four main phases of volcanic activity, which initiated in the Pliocene with the formation of the Christiana volcano (phase 1). The formation of the current southwest-northeast–trending rift system (phase 2) was associated with the evolution of two distinct volcanic centers, the newly discovered Poseidon center and the early Kolumbo volcano. Phase 3 saw a period of widespread volcanic activity throughout the entire rift. The ongoing phase 4 is confined to the Santorini caldera and Kolumbo volcano. Our study highlights the fundamental tectonic control on magma emplacement and shows that the CSKVF evolved from a volcanic field with local centers that matured only recently to form the vast Santorini edifice.

Volcanic island sector collapses have the potential to trigger devastating tsunamis and volcanic eruptions that threaten coastal communities and infrastructure.Considered one of the most hazardous volcano-tectonic regions in the world, the Christiana-Santorini-Kolumbo Volcanic Field (CSKVF) lies in the South Aegean Sea in an active rift zone. Previous studies identified an enigmatic voluminous mass-transport deposit west and east of Santorini emplaced during the early evolution of the edifice. However, the distribution and volume as well as the nature and emplacement dynamics of this deposit remained unknown up to now. In this study, we use an extensive dataset of high-resolution seismic profiles to unravel the distribution and internal architecture of this deposit. We show that it is located in all basins surrounding Santorini and has a bulk volume of up to 125 km 3 , thus representing the largest known volcanic island mass-transport de-EAGE PREINE et al.

The interplay of volcanism and tectonism has shaped many volcanic systems across the world (Acocella, 2021). Regional tectonics weakens the crust through increased faulting and fracturing creating pathways for magmatic fluids to ascend to the surface, although the controlling mechanisms remain elusive (e.g., Hill et al., 2002;Manga & Brodsky, 2006). Our current knowledge of volcano-tectonic feedback mechanisms is based mostly on the interplay of earthquakes and volcanic eruptions on time scales ranging from minutes to decades by direct observations or historic records (e.g., Manga & Brodsky, 2006;Watt et al., 2009). These studies revealed that tectonic movements can change stress levels in the crust and the underlying mantle, influencing production and ascent rates, as well as sizes and explosivities of eruptions. In turn, volcanism can alter the stress of the crust by accommodating extensional strain and inhibiting the formation of faults (Faulds & Varga, 1998) highlighting complex feedback