Presentation by Dr. Jonas Preine, Woods Hole Oceanographic Institution.
Title: Towards an understanding of volcano-tectonic interactions at Santorini-Kolumbo
Abstract:
The Santorini–Kolumbo volcanic field is one of the most hazardous volcanic centers in Europe, as evidenced by its VEI-5 explosive eruptions of 726 CE and 1650 CE and repeated bradyseismic crises, most recently in 2011–2012 and 2025. To investigate the interplay between volcanism and tectonics in this system, International Ocean Discovery Program (IODP) Expedition 398 recovered 12 deep drill cores from volcano-sedimentary infill of marine rift basins and the Santorini caldera. Integrated volcanic records from four sites northeast of Santorini reveal more than 200 Santorini tephras and 19 Kolumbo tephras intercalated within marine sediments. Tephra stratigraphies were correlated chemically between sites, either as products of individual eruptions or as composite packages of tephra layers, providing a high-resolution eruptive timeline. By integrating these ground-truthed stratigraphies with an extensive seismic dataset from eight expeditions, we refine previous seismo-stratigraphic frameworks and directly link basin-fill architecture to volcanic events.
Our combined stratigraphic and structural analysis reveals a previously unrecognized neotectonic graben that hosts the Kolumbo volcanic field and extends toward Santorini. We show that this graben developed through accelerated rifting prior to the onset of highly explosive volcanism at Santorini and the emergence of Kolumbo Volcano. Subsequent eruptions generated widespread volcanic megaturbidites that buried the graben structure, concealing it from the present-day seafloor. Within this tectonic depression, volcanism at both Santorini and Kolumbo localized along internal deformation zones that acted as preferred magma pathways. The co-location of both volcanoes within the same graben indicates that their activity is synchronized by regional tectonic stresses. Notably, no volcanic center is known to have evolved outside this structure, underscoring the fundamental spatial control of crustal extension on volcano emplacement in the central Aegean arc.
Zoom Link:
https://columbiauniversity.zoom.us/j/99190371015?pwd=XjhGnamRyYsrPxxkw4NeCcbTswBDMn.1
Meeting ID: 991 9037 1015
Passcode: 654464
