| Updated: | Wednesday, 14 March, 2012 at 04:18 UTC |
| Description | |
| The volcanic caldera on the picturesque tourist island of Santorini is showing signs of unrest. But researchers detecting the caldera's movement say it doesn't necessarily mean an eruption is imminent. The Greek island was the site of one of the most massive volcanic eruptions in history 3,600 years ago. That eruption, which created tsunamis 40 feet (12 meters) tall, may have spawned the legend of the lost city of Atlantis. The volcano last erupted in 1950, albeit on a much smaller scale. Global positioning system (GPS) sensors placed on the caldera have detected renewed movement after decades of peace. The earth around the caldera (a depression at the top of a volcano) is deforming, or expanding outward, researchers report in an upcoming article in the journal Geophysical Research Letters. GPS instruments on the northern part of Santorini have moved between 1.9 and 3.5 inches (5 to 9 centimeters) since January 2011, said study researcher Andrew Newman, a geophysicist at Georgia Tech in Atlanta. "What we're seeing now is the first significant deformation and the first deformation that has any significant earthquake activity associated with it," Newman told LiveScience. In the same time period, the magma chamber under Santorini has swollen by almost 500 million cubic feet (14 million cubic meters). Newman and his colleagues say it's unlikely that the deforming caldera portends an eruption. Excavations of extinct volcanoes suggest that 90 percent of the time, below-ground magma movements don't end in eruption. A similar caldera system, the Long Valley Caldera in California, started deforming in 1980, Newman said. It then quieted again until 1989, repeating the cycle in 1997 and 2002, with nary an eruption. If a Santorini eruption did occur, Newman said, it would be nothing like the Minoan eruption of 1650 B.C. that birthed the myth of Atlantis. That eruption was a once-in-100,000-year event, and the expansion of the magma chamber happening now is only 1 percent of what would have gone on prior to the ancient blast. Geophysicists are keeping an eye on the caldera, however. An eruption could generate local tsunamis within the Santorini archipelago, Newman said, damaging ports and disrupting ship traffic. Even if the volcano doesn't erupt, the shifting caldera could increase earthquake risk, and the island cliffs are vulnerable. "We don't need an eruption to have earthquake-induced landslides," Newman said. There's no telling how long the deformation will continue, but it could stretch years or decades, perhaps cycling between activity and peace, Newman said. While there is no reason to be alarmed, the restless caldera is important for scientific study, he added. "It is one of very few of these really large caldera volcanoes," he said. "So any information we gather from ongoing activity adds significantly to our database of how these systems evolve." | |
| Updated: | Wednesday, 14 March, 2012 at 04:19 UTC |
| Description | |
| The Greek island of Santorini is showing increasing signs of volcanic activity, a U.S. researcher says. Monitoring stations on the island indicate the Santorini caldera is awake again and rapidly deforming, said Georgia Tech researcher Andrew Newman, who has studied Santorini since 2006 after placing more than 20 GPS stations on the popular tourist island. "After decades of little activity, a series of earthquakes and deformation began within the Santorini caldera in January of 2011," Newman said. "Since then our instruments on the northern part of the island have moved laterally between five and nine centimeters (2 inches to 3-1/2 inches). "The volcano's magma chamber is filling, and we are keeping a close eye on its activity." The chamber has expanded by nearly 500 million cubic feet since last January, Newman said. "That could be dangerous," he said. "If the caldera erupts underwater, it could cause local tsunamis and affect boat traffic, including cruise ships, in the caldera. Earthquakes could damage homes and produce landslides along the cliffs." Santorini has been relatively calm since its last eruption in 1950, a Georgia Tech release said Tuesday. | |
__._,_.___
No comments:
Post a Comment