The use of surveillance cameras for the rapid mapping of lava flows. An application to mount Etna volcano

In order to improve the observation capability in one of the most active volcanic areas in the world, Mt. Etna, we developed a processing method to use the surveillance cameras for a quasi real-time mapping of syn-eruptive processes. Following an evaluation of the current performance of the Etna permanent ground NEtwork of Thermal and Visible Sensors (Etna_NETVIS), its possible implementation and optimization was investigated to determine the locations of additional observation sites to be rapidly set up during emergencies. A tool was then devised to process time series of ground-acquired images and extract a coherent multi-temporal dataset of georeferenced map. The processed datasets can be used to extract 2D features such as evolution maps of active lava flows. The tool was validated on ad-hoc test fields and then adopted to map the evolution of two recent lava flows. The achievable accuracy (about three times the original pixel size) and the short processing time makes the tool suitable for rapidly assessing lava flow evolutions, especially in the case of recurrent eruptions, such as those of the 2011-2015 Etna activity. The tool can be used both in standard monitoring activities and during emergency phases (eventually improving the present network with additional mobile stations) when it is mandatory to carry out a quasi-real-time mapping to support civil protection actions. The developed tool could be integrated in the control room of the Osservatorio Etneo, thus enabling the Etna_NETVIS for mapping purposes and not only for video surveillance lava flows. The tool was validated on ad-­‐‑hoc test fields and then adopted to map the evolution of two recent lava flows. The achievable accuracy (about 3 times the original pixel size) and the short processing time makes the tool suitable to rapidly assess lava flow evolutions, especially in case of recurrent eruptions like those of the 2011-­‐‑2015 Etna activity. The tool can be used both in standard monitoring activities and during-­‐‑emergency phases (eventually improving the present network with additional mobile stations) when it is mandatory to carry out a quasi-­‐‑real-­‐‑time mapping to support civil protection actions. The developed tool could be integrated in the control room of the Osservatorio Etneo