GRSG Conference 2022: Orbit to Outcrop

Poster Title: Remote sensing and numerical modelling to characterise tsunamigenic volcanic mass flows of the 3rd of July 2019 events at Stromboli volcano, Italy

Author: Irene Manzella


Tsunamis caused by landslides and pyroclastic denisity currents in volcanic environments could constitute lethal hazard. However data available are scarce and often poorly constrained.

Many tsunamigenic instabilities (sub-aerial and/or submarine) have taken places along the flanks of the Stromboli Volcano (Italy). After the 30 December 2002 landslide–induced tsunami which caused extensive damage, a series of buoys have been installed around the island to monitor and record tsunami wave heights around Stromboli at all time. Associated with the 3rd of July 2019 paroxysm two subaerial Pyroclastic Density Currents and one submarine landslide were triggered and a tsunami wave has been registered by 3 buoys in different locations and with different heights.

These events were back-analysed with the two fluids version of VolcFlow, a continuum mechanics model developed by the Laboratoire Magmas et Volcans (France). For this purpose, pre and post event characterisation were carried out using different remote sensing methodologies. Subareal topographic change detection was analysed by comparing DEMs generated from PLÉIADES-1 tri-stereo satellite imagery acquired on 13 June 2019 and 8 October 2019, whereas submarine changes were assessed with three bathymetric surveys obtained between 2018 and 2020.

With the best fitting input parameters found from the back-analysis, it has been then possible to assess threshold values of volume and discharge of mass flows which could trigger significant tsunami waves. This allows improving the early warning system on the Stromboli Island and ultimately increasing awareness and understanding of this complex and destructive phenomena.