The south Aegean Sea islands of Santorini are showing signs of unrest for the first time in more than half a century. Satellite data confirm they've risen about 14 cm since January 2011.
To map the movement, the scientists used radar data from the European Space Agency's Envisat satellite from March to December 2011 and from the German TerraSAR-X mission from July 2011 to April 2012.
To ensure accurate measurement, the team also used Global Positioning System receivers and an island-wide network of triangulation stations. The study outlines that the total amount of vertical movement is now approaching 8“14 cm at some points on the Kameni islands, and the whole caldera is around 14 cm wider now than it was at the beginning of 2011.
The Santorini volcano's last major explosive eruption was about 3,600 years ago. This event formed a large crater, or caldera, which is now flooded by the sea. For the past 2,000 years, Santorini has shown different behaviour patterns, with small eruptions of lava every few tens or hundreds of years, slowly building a new volcanic edifice from the sea floor.
The Kameni islands, which lie in the middle of Santorini's large flooded crater, form the top of this youngest part of the volcano. The last eruption of the Kameni islands was in 1950. For the next 60 years, Santorini was quiet.
In January 2011, a series of small earthquakes began beneath the islands. Most were small enough that they could only be detected with sensitive seismometers, but several were felt by the local residents.
Image courtesy of M. Parks