Constraining the landscape of Late Bronze Age Santorini prior to the Minoan eruption: insights from volcanological, geomorphological and archaeological findings

One of the best known places on Earth where volcanology meets archaeology and history is the volcanic island of Santorini (Thíra), Greece. It is famous for the cataclysmic Late Bronze Age (Minoan) Plinian eruption which destroyed the Minoan culture that flourished on the island. Hosting a central, flooded caldera bay and, within that, the active islands of Palaea and Nea Kameni, Santorini volcano has been the focus of international research efforts for over one and a half centuries. In this paper, we summarize recent findings and related ideas about the Minoan physiography of the island, also known as Strongyli, from a volcanological, geomorphological and archaeological point of view. As proposed as early as the 1980s, a central caldera bay existed prior to the Late Bronze Age. Probably characterised by a smaller size and located in the northern part of the present-day caldera, this earlier caldera bay was formed during the previous Plinian eruption – called Cape Riva eruption – c. 22,000 years ago. Within the caldera bay, a central island, Pre-Kameni, existed, named after the present-day Kameni Islands. High-precision radioisotopic dating revealed that Pre-Kameni started to grow c. 20,000 years ago. Whereas volcanologists have accepted and refined the caldera concept, archaeologists have generally favoured the theory of an exploded central cone instead of a pre-existing central caldera. However, analysis of the Flotilla Fresco, one of the wall paintings found in the Bronze Age settlement of Akrotiri, reveals the interior of a Late Bronze Age caldera that may be interpreted as a realistic landscape. Approximately 3600 years ago, the island of Strongyli was destroyed during the explosive VEI = 7 Minoan eruption. Pre-Kameni was lost by this eruption, but its scattered fragments, together with other parts of Strongyli, can be recovered as lithic clasts from the Minoan tuffs. On the basis of photo-statistics and granulometry of the lithic clasts contained in the Minoan tuffs, complemented by volumetric assessment of the erupted tephra and digital elevation model (DEM) analysis of alternative models for the pre-eruptive topography, the volume of Pre-Kameni can be constrained between 1.6 and 3.0 km3, whereas the volume of the destroyed portion of the ring island of Strongyli between 9.1 and 17.1 km3. Of these, the larger values are considered more realistic, and imply that most of the destroyed part of Strongyli was incorporated as lithic components in the Minoan tuffs, whereas up to 3 km3 of Strongyli might have been downfaulted and sunken during caldera formation and is not accounted for in the lithics