Volcano generated tsunami recorded in the near source

Abstract

Volcano sector collapse and pyroclastic density currents are common phenomena on active volcanoes and potentially a fatal source of tsunami waves which constitute a serious hazard for local as well as distant coastal population. Several examples in recent history, warn us on the urgent need to improve our mitigation counter-actions when tsunamis have volcanic origin. However, instrumental record of tsunami generated by mass movement along a volcano flank are still rare and not well understood yet. Small tsunamis (≤1 m) induced by pyroclastic density currents associated to violent explosions of Stromboli volcano were recorded in near-source conditions (<1.6 km). We show how tsunami waveform remains unaltered regardless of the two orders of variability in the landslide volume and dynamics. This unprecedented record is also providing the lesson to develop unconventional warning strategies necessary when the tsunamigenic source is expected to be very close (<10 minutes) to densely populated coasts and with a limited time to issue an alert based on simulation of wave propagation and inundation.