Findings presented at the International Forum on Satellite Earth Observation for Geohazard Risk Management taking place in Santorini this week indicate that the archipelago’s Nea Kameni volcano has experienced some unrest recently.
Santorini is a circular archipelago in the Aegean Sea, with the uninhabited island of Nea Kameni at its centre. The remnants of a caldera which was formerly one single island, it remains the most active volcanic area in the South Aegean Volcanic Arc.
Although the volcano has been dormant for more than half a century, data from the Envisat satellite shows that there has been some seismic activity since January 2011, resulting in deformation of the ground. One of the largest eruptions in history occurred on Santorini almost 3600 years ago, but the last eruption was recorded in 1950.
Ground deformation is detected by a technique known as Differential Interferometric Synthetic Aperture Radar (DInSAR), whereby the differences in signal reflection between two or more radar images are compared.
"Monitoring to detect any change of the status of the volcano presents a further step towards the understanding of physical processes related to volcanic eruptions that can lead to natural disasters," commented Professor Issaak Parcharidis from the Department of Geography at the Harokopio University of Athens.
Despite loss of contact with Envisat on the 8th
April this year, scientists continue to use the data provided by the satellite over the last decade to monitor volcanic activity, as well as for many other applications.
The data illustrates a 5 cm rise in the northeastern region of Nea Kameni and a 3 to 4 cm rise elsewhere on the island in 2011. Satellites can measure such small changes even from an orbit 800 km above the Earth’s surface.
In early 2012, however, the rate of deformation was observed to slow down considerably, allaying concerns for the safety of island inhabitants.
"After evaluation of local seismic activity, deformation and physicochemical changes, [we] concluded that during the last months the volcano presents a very limited activity, much lower than that of 2011," clarified Professor Kosmas Stylianidis, Head of the Special Scientific Committee for the Monitoring of Santorini Volcano. "The committee, in its monthly report of April to the government, advises the application of no restrictive measure concerning the mobility of population."
The information relayed by Envisat - essential for prediction of geohazards in particular - will continue to be supplied by successive satellite missions such as the Sentinel family.