Post-eruptive flooding of Santorini caldera and implications for tsunami generation

• Published in: Nature communications Vol. 7; no. 1; p. 13332
• Main Authors: Nomikou, P., Druitt, T. H., Hübscher, C., Mather, T. A., Paulatto, M., Kalnins, L. M., Kelfoun, K., Papanikolaou, D., Bejelou, K., Lampridou, D., Pyle, D. M., Carey, S., Watts, A. B., Weiß, B., Parks, M. M.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 08.11.2016; Nature Publishing Group; Nature Portfolio
• Subjects: 704/2151/598; 704/4111; Bronze Age; Dams; Drainage; Earth science; Earth Sciences; Humanities and Social Sciences; Landslides & mudslides; Morphology; multidisciplinary; Science; Science (multidisciplinary); Sciences of the Universe; Sediments; Tsunamis; Volcanoes; Volcanology; United Kingdom > UK; France; Santorini
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms13332

Caldera-forming eruptions of island volcanoes generate tsunamis by the interaction of different eruptive phenomena with the sea. Such tsunamis are a major hazard, but forward models of their impacts are limited by poor understanding of source mechanisms. The caldera-forming eruption of Santorini in the Late Bronze Age is known to have been tsunamigenic, and caldera collapse has been proposed as a mechanism. Here, we present bathymetric and seismic evidence showing that the caldera was not open to the sea during the main phase of the eruption, but was flooded once the eruption had finished. Inflow of water and associated landsliding cut a deep, 2.0–2.5 km 3 , submarine channel, thus filling the caldera in less than a couple of days. If, as at most such volcanoes, caldera collapse occurred syn-eruptively, then it cannot have generated tsunamis. Entry of pyroclastic flows into the sea, combined with slumping of submarine pyroclastic accumulations, were the main mechanisms of tsunami production. The Bronze Age eruption of Santorini is known to have generated tsunamis with caldera collapse as the likely mechanism. However, new bathymetric and seismic data presented by Nomikou et al . show that the entry of pyroclastic flows into the sea is the most likely tsunami-generating mechanism at Santorini.