Post-eruptive flooding of Santorini caldera and implications for tsunami generation.
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 km3, 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.
National and Kapodistrian University of Athens, Department of Geology and Geoenvironment, Panepistimioupoli Zografou, Athens 15784, Greece.
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Nomikou
Laboratoire Magmas et Volcans, Université Blaise Pascal-CNRS-IRD, Campus des Cézeaux, Aubière 63178, France.
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Druitt
Institute for Geophysics, University of Hamburg, Bundesstrasse 55, Hamburg 20146, Germany.
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Hübscher
Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK.
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Mather
Géoazur CNRS, Bât 4, 250 rue Albert Einstein, Sophia Antipolis, Valbonne 06560, France.
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Paulatto
Department of Earth Sciences, Durham University, Durham DH1 3LE, UK.
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Kalnins
Laboratoire Magmas et Volcans, Université Blaise Pascal-CNRS-IRD, Campus des Cézeaux, Aubière 63178, France.
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Kelfoun
National and Kapodistrian University of Athens, Department of Geology and Geoenvironment, Panepistimioupoli Zografou, Athens 15784, Greece.
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Papanikolaou
National and Kapodistrian University of Athens, Department of Geology and Geoenvironment, Panepistimioupoli Zografou, Athens 15784, Greece.
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Bejelou
National and Kapodistrian University of Athens, Department of Geology and Geoenvironment, Panepistimioupoli Zografou, Athens 15784, Greece.
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Lampridou
Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK.
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Pyle
Graduate School of Oceanography, University of Rhode Island, 215 S. Ferry Road, Narragansett, Narragansett, Rhode Island 02882, USA.
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Carey
Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK.
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Watts
Institute for Geophysics, University of Hamburg, Bundesstrasse 55, Hamburg 20146, Germany.
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Weiß
Nordic Volcanological Center, Institute of Earth Sciences, University of Iceland, Reykjavík IS-101, Iceland.
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Parks