During a recent expedition, researchers at the Oxford University and the University of Bristol were able to discover the existence of a large bubble of magma under the Greek island of Santorini, where a devastating volcanic eruption occurred millennia ago.
Following the event, the small island chain was covered in pumice, which is volcanic rocks that contain a lot of air bubbles. The image to the left shows the former caldera of the volcano, as it appears today. The submerged area in the middle was once above the surface of the Aegean Sea.
During the latest expedition to study the former island, the team found that the molten rock chamber under Santorini expanded by as much as 10 to 20 million cubic meters (353 to 706 million cubic feet).
As a result, the surface of the island rose between 8 and 14 centimeters (3.1 to 5.5 inches), as demonstrated by data collected via the Global Positioning System (GPS) constellation. The spacecraft can measure land deformations with a high degree of precision.
The increase in magma chamber volume occurred between January 2011 and April 2012, the team explains. Details of the study were published in this week's issue of the top journal Nature Geoscience.
Geologists are worried about Santorini because the volcano last erupted around 3,600 years ago. At this point, any sign of increased activity could imply that it's getting ready to blow up again. Back in January 2011, special detectors on the island recorded small tremors deep underground.
“During my field visits to Santorini in 2011, it became apparent that many of the locals were aware of a change in the behavior of their volcano,” explains study author Michelle Parks, who is based at the Oxford Department of Earth Sciences.
“The tour guides, who visit the volcano several times a day, would update me on changes in the amount of strong smelling gas being released from the summit, or changes in the color of the water in some of the bays around the islands,” she adds.
Though the extra material in the magma chamber and the 2011 tremors could be very well interpreted as signifying that an eruption is imminent, researchers say that nothing is certain. Over the past few months, the number of small tremors has subsided somewhat, instead of increasing.