The Hidden Giant: How a rift pulse triggered a cascade of sector collapses and voluminous secondary mass‐transport events in the early evolution of Santorini

Abstract

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.

Volcano‐Tectonic Evolution of the Christiana‐Santorini‐Kolumbo Rift Zone

“…The internal reflections of Unit 6 are mostly sub‐parallel to the seafloor while the deeper reflections (h6‐h2) show a pronounced dip towards the Santorini‐Anafi Fault (Figure 2b). Unit 5 thickens towards the foot of the Santorini‐Anafi Fault, where we identify a confined area with irregular reflections interpreted as a slump deposit originated from the Santorini‐Anafi Fault (Figure 2b) (Nomikou, Hübscher, et al., 2018; Preine, Karstens, Hübscher, Crutchley, et al., 2022). Unit 4 is only present at the foot of the Santorini‐Anafi Fault and pinches out towards the SE onlapping the underlying unconformity h4 (Figure 2b).…”

“…Both centers produced volcanoclastic deposits that are intercalated within the sedimentary strata of the hosting Christiana and Anhydros Basins. A distinct change in the volcanic behavior occurred at ∼0.7 Ma after the Santorini mass‐wasting cascade occurred that transported up to 125 km³ of sediments from Christiana and Santorini into the surrounding basins (Figure 1b) (Preine, Karstens, Hübscher, Crutchley, et al., 2022). Afterward, in the third phase, volcanism occurred throughout the entire CSK field forming a series of volcanic cones, as well as the onshore exposed Akrotiri rhyolitic centers, the Peristeria stratovolcano, and the Akrotiri cinder cones (Figure 1b) (Preine, Karstens, Hübscher, Nomikou, et al., 2022).…”

“…Modified from Preine, Karstens, Hübscher, Nomikou, et al. (2022). TPF: Thera Pyroclastic Formation; K1‐K5: Kolumbo eruptions.…”

“…(2019) and Preine, Karstens, Hübscher, Crutchley, et al. (2022). Bathymetry from Nomikou, Hübscher, et al.…”

Heralds of Future Volcanism: Swarms of Microseismicity Beneath the Submarine Kolumbo Volcano Indicate Opening of Near‐Vertical Fractures Exploited by Ascending Melts

“…Precise dating is only available for the latest eruption of Kolumbo. However, a recently established regional stratigraphic framework of the entire Christiana‐Santorini‐Kolumbo region estimates that the deposits of older eruptions have approximate ages of 0.35 Ma, 0.45 Ma, 0.9 Ma and older than 1.0 Ma (Preine, Karstens, Hübscher, Crutchley, et al.,2022, Preine, Karstens, Hübscher, Nomikou, et al., 2022).…”