Volcanic Hazard Monitoring Using Multi-Source Satellite Imagery.

Satellite remote sensing is playing an increasing role in volcano monitoring, not only at little-known and remote volcanoes where in-situ data are often unavailable, but also at well-monitored volcanoes to complement ground-based measurements. The synoptic view captured by multi-source satellite imagery over volcanoes can benefit hazard monitoring efforts, both following the different phases and intensities of an eruption, as well as helping in nowcasting and eventually forecasting the areas potentially threatened by hazardous phenomena. Here we demonstrate how satellite data from different sources can be combined to refine the satellite-derived radiant heat flux and time-averaged discharge rates (TADRs) estimation, and to improve real-time monitoring and nowcasting of eruptive events. This is achieved by cross-referencing TADRs obtained from low spatial/high temporal resolution satellite data (e.g. MODIS, SEVIRI, VIIRS, SLSTR) with maps of volcanic deposits including the time-varying evolution of lava flow emplacement derived from medium spatial resolution multispectral satellite data (e.g. EO-ALI, Landsat, Sentinel-2, ASTER), and with detailed three-dimensional maps of volcanic deposits retrieved from the topographic monitoring by using stereo or tri-stereo optical data (e.g. Pleiades, PlanetScope, SkySat, ASTER). Finally, satellite-derived parameters are used as input and validation for the numerical modelling of lava flow scenarios. This strategy is here applied to recent eruptions occurred on Etna, Stromboli and Nabro volcanoes.