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Tsunamis and pyroclastic flows over water during the 1815 eruption of Tambora

Raphaël Paris1, Bachtiar Mutaqin2, Olivier Roche1, Alizée Meilhaud1, François Nauret1, Simon Falvard1, Alexis Bougouin3

  • Affiliations: 1 Laboratoire Magmas et Volcans, Université Clermont Auvergne, CNRS, IRD, OPGC, Clermont-Ferrand, France 2 Faculty of Geography, Universitas Gadjah Mada, Yogyakarta, Indonesia. 3 Dipartimento di Ingegneria Informatica, Universita della Calabria, Rende, Italy

  • Presentation type: Poster

  • Presentation time: Thursday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 149

  • Programme No: 2.2.13

  • Theme 2 > Session 2

Abstract

The physical processes leading to tsunami during a volcanic eruption are often poorly documented and poorly constrained, thus seriously complicating hazard assesment and the implementation of early warning strategies. These difficulties apply in particular to major explosive eruptions, during which the sources of tsunami are multiple (underwater explosions, rapid ground subsidence, eruptive column collapse, pyroclastic density currents, and atmospheric waves). Among all these mechanisms, the generation of tsunamis by pyroclastic density currents involves complex physical processes that can be understood on a laboratory scale (channel experiments). But the lessons learned from these experiments need to be correlated with field data on natural events. We here take the example of the Tambora eruption in 1815 as a case study, with the aim of identifying tsunami deposits in the coastal stratigraphy of the Saleh Bay, 40-50 km West of the volcano. The volcano-sedimentary sequences studied provide information on the chronology of events (tephra falls, pyroclastic flows, tsunamis) and thus place constraints on the magnitude and source of tsunamis in the framework of the different stages of the eruption. We also document the propagation of pyroclastic flows over 20 km of water in the bay. These field data are then compared with empirical laws derived from experimental work, enabling tsunami wave heights to be related to pyroclastic flow parameters (flow density, front height, front velocity, mass flux) at the impact with water.