Source and significance of pumices in tsunami deposits: examples from Tenerife (Canary Islands), Santorini (Greece) and Krakatau (Indonesia) volcanoes.

Abstract:

Volcanic eruptions are quite often associated with tsunamis, and particularly caldera-forming eruptions near the coasts (e.g. Santorini, Krakatau, Aniakchak, Kikai). The main tsunamigenic processes are the entrance of massive pyroclastic flows in water, and flank instability, even if other processes might be involved (e.g. explosions). Fresh tephras are often preserved in sedimentary deposits left inland by tsunamis associated with volcanic eruptions. We review the different sources and incorporation mechanisms of pumices in tsunami deposits, and their significance in terms of volcanic processes, hydrodynamic processes (tsunami inundation) and their possible interactions. Three examples are adressed: the Krakatau 1883 eruption, the Minoan Thera eruption, and the El Abrigo eruption / Teno tsunami in Tenerife.