Sicily and Mount Etna (by European Space Agency)
Europe’s largest active volcano, the 3350 metre-high Mount Etna in Sicily, Italy, resumed eruptions in September 2006. It became highly active in November and its ash clouds forced local authorities to close nearby Fontanarossa airport. This image was taken on 25 November 2006 by Envisat’s Medium Resolution Imaging Spectrometer (MERIS) instrument, and shows smoke from the volcano.
Satellite data can be used to detect the signs of change that may foretell volcanic eruptions. Once an eruption begins, optical and radar instruments see the various phenomena associated with it, including lava flows, mud slides, ground fissures and earthquakes. Atmospheric sensors on satellites can also identify the gases released by the eruption, as well as quantify their wider environmental impact.