Satellite images for studying the surface temperatures of volcanoes around the world. A team of researchers from INGV has developed a new system that has made it possible to follow the recent eruption of Etna
Through the images provided by the satellites of the Copernicus Sentinel2A system, the National Institute of Geophysics and Volcanology (INGV), has followed the recent eruption of Etna thanks to a system that estimates, through infrared optical sensors, the presence of high temperature (hot spot) in volcanic regions. Developed within the activities of the ESA-GEP (Geohazard Exploitation Platform) project and funded by the European Space Agency (ESA), the INGV system, currently in the operational test phase on a selected number of active volcanoes, has allowed for the first time to be able to follow the recent eruption of Etna, using images with a spatial resolution of 20 metres.
“The ESA_GEP project”, explains Malvina Silvestri, INGV technologist, “generated information on the geometry of the lava flows related to the eruption of Etna, processing the images acquired at 10.45 (local time) on 16 March, at 10.50 (local local time) on 19 March and at 11.45 (local time) on 26 March. The images show the lava emitted by the volcano (figure 1, figure 2 and figure 3) and, in particular, clearly highlight the presence of flows emitted at successive times and located in two different areas. The longer one passes west of the Barbagallo Mountains, while the lava flow that passes east is less fed and, therefore, proceeds more slowly".
The Sentinel-2A mission, launched in June 2015, transmitted multi-spectral optical images, thanks to the 13 high spatial resolution bands that monitor changes in the soil and vegetation. Sentinel-2A with its twin satellite, Sentinel-2B, in orbit since March 7, ensure, in fact, a passage over the same area every 2-3 days at medium latitudes. The data is distributed free of charge to all users.
With the aim of increasing the number of observations, images acquired by the Landsat-8 satellite mission, launched in February 2013 and distributed free of charge by the United States Geological Survey (USGS), were also analysed. Through an INGV-USGS agreement, Landsat-8 acquisitions were also activated during night passes over Etna, Vesuvius and Campi Flegrei to increase observations on active Italian volcanoes. Landsat-8, which acquires 11 visible-infrared bands with a resolution on the ground of 30 meters and 100 meters (2 bands in the thermal infrared), makes it possible to integrate the data from the Sentinel-2A/2B satellite and provides the the surface temperature and the trend of the lava flows (figure 4).
Figures 5-9 show the lava flow progression in the days between 16 and 26 March.
“The study shows, once again, how space remote sensing is an important support for volcanic monitoring and surveillance activities. It not only provides a synoptic view of safety against on-site surveys, but also a valuable tool for monitoring volcanoes in remote, not easily accessible areas. All thanks to the new data policy of the Space Agencies oriented towards the free distribution of satellite data to Institutional Bodies", concludes Silvestri.
Figure 1 False-color image using Sentinel-4,8A bands 12 and 2 (March 16, 2017). The lava flow is highlighted in red
Figure 2 False-color image using Sentinel-4,8A bands 12 and 2 (March 19, 2017). The lava flow is highlighted in red
Figure 3 False-color image using Sentinel-4,8A bands 12 and 2 (March 26, 2017). The lava flow is highlighted in red
Figure 4 False color image using Landsat4,5 bands 7 and 8 (March 18, 2017). The lava flow is highlighted in red
Figure 5 Map of the lava flow obtained by processing the Sentinel-2A datum of March 16, 2017. The flow at the satellite acquisition date is highlighted in orange
Figure 6 Map of the lava flow obtained by processing the Landsat8 datum of 18 March 2017. The lava flow at the satellite acquisition date is highlighted in red
Figure 7 Map of the lava flow obtained by processing the Sentinel-2A datum of March 19, 2017. The flow at the satellite acquisition date is highlighted in green
Figure 8 Map of the lava flow obtained by processing the Sentinel-2A datum of March 26, 2017. The lava flow at the satellite acquisition date is highlighted in purple
Figure 9 Overlay of the lava flows erupted in the period 16 to 26 March 2017
LINK:
http://www.esa.int/Our_Activities/Observing_the_Earth/Earth_s_most_active_volcanoes_on_satellite_watch
http://www.esa.int/ita/ESA_in_your_country/Italy/L_eruzione_dell_Etna_ripresa_dal_satellite