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

Abstract

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.

Modeling tsunami propagation and the emplacement of thumbprint terrain in an early Mars ocean

“…For our analysis, we used the numerical model VolcFlow [ Kelfoun and Druitt , ] to compare the propagation of an ocean impact‐generated tsunami with the distribution of lobate deposits found along the dichotomy boundary. The VolcFlow model was initially developed to simulate volcanic flows such as dense pyroclastic flows and debris avalanches [ Kelfoun and Druitt , ] and was subsequently modified for the simulation of the dynamics of tsunamis generated by volcanic destabilizations [e.g., Kelfoun et al ., ; Giachetti et al ., ; Nomikou et al ., ].…”

“…The deposits are~3 billion years old (Late Hesperian/Early Amazonian transition). The two power laws [Hartmann, 2005] [Kelfoun and Druitt, 2005] and was subsequently modified for the simulation of the dynamics of tsunamis generated by volcanic destabilizations [e.g., Kelfoun et al, 2010;Giachetti et al, 2011;Nomikou et al, 2016].…”

An introduction to seismic diffraction

“…The region was found to be largely influenced structurally through prevailing volcanism (Hübscher et al, 2015;Nomikou et al, 2016b). One of the dominant features is a large submarine volcano -the Kolumbo seamountwhose activity sustainably shaped the tectonic landscape of the region and is even thought to have been involved in Tsunami generation (Nomikou et al, 2016a). As examples, Figure 17 and Figure 18 show two different sedimentary environments adjacent to the Kolumbo seamount.…”

Landslide Risk Assessment of the Santorini Volcanic Group

“…Druitt et al (1999) described the geological (Pyle & Elliott 2006;Nomikou et al 2014 and references therein). The LBA caldera is 10x7 km wide, comprises of three flat-floored basins around the Kameni edifices, and is connected to the sea by three straits (one to the NW and two to the SW) (Nomikou et al 2016). There are no officially recorded landslides from any local authority (i.e.…”