Dig into the black sand of Deception Island, off the coast of the Antarctic Peninsula, and hot water percolates up, heated by geothermal activity. The horseshoe-shaped spit of land is itself the flooded caldera of an active volcano and home to more than 50 volcanic craters—markers of past eruptions. Now, scientists have shown that ash lofted by a hypothetical eruption on Deception Island would potentially disrupt air traffic as far away as South America, Australia, and Africa.
The findings show that Antarctica’s volcanoes can have an effect across the world, says Charles Connor, a geoscientist at the University of South Florida in Tampa not involved in the research. “We have to reassess the potential hazards for global transportation networks posed by even these remote volcanoes.”
Adelina Geyer, a geologist at the Institute of Earth Sciences Jaume Almera in Barcelona, Spain, and colleagues focused on Deception Island because of its history of eruptions—30 or so in the past 10,000 years, and one as recently as 1970. It is also a popular destination: Both Argentina and Spain manage scientific research bases on the island, and tourists come to admire the world’s largest colony of chinstrap penguins and the rusted boilers and tanks that are relics of the early 20th century whaling industry there.
Airborne ash is a serious problem for aircraft because it melts inside of engines and gums up fuel lines. And it doesn’t show up on radar. There have been hundreds of reported incidents of aircraft encountering volcanic ash, including the 1989 case of KLM flight 867, which lost power in all four engines and fell more than 13,000 feet after flying through an ash cloud from Alaska’s Redoubt Volcano. (The pilots managed to restart the engines, and the plane landed safely in Anchorage.) When Iceland’s Eyjafjallajökull erupted in 2010, its ash clouds prompted officials to close airspace across Europe, resulting in economic losses estimated to be billions of dollars.
For large eruptions on Deception Island, ash would be prevalent on global scales, the team concludes this week in Scientific Reports. Ash spewed high up into the stratosphere would encounter strong winds whipping around the South Pole. These circular winds—known as the polar vortex—move at speeds up to 60 meters per second and can send ash swirling far from its source. The team found that dangerous levels of airborne ash—exceeding flight safety thresholds of 2 milligrams per cubic meter—persisted thousands of kilometers from Deception Island, rendering routes toward major airports such as Buenos Aires unsafe for flying.
But even ash that wasn’t lofted as high still tended to disperse widely, the team found. That’s because ash injected into a lower layer of the atmosphere known as a troposphere encountered chaotic, meandering atmospheric waves that carried it as far away as South America, Australia, and Africa.
The researchers also tested moving the site of the eruption to Mount Erebus, another active Antarctic volcano located at a latitude of –77° near McMurdo Station, the largest research base in Antarctica. They found that higher plumes still resulted in transcontinental ash dispersal, but ash from lower plumes—generally less than 10 kilometers—tended to remain confined near the South Pole because of the less-intense, low-elevation winds at high latitudes.
In February 2018, part of Geyer’s team will embark on a roughly weeklong journey to Deception Island via air and sea to gather data that could help calibrate their model. She says she and her colleagues will be studying recent eruptions “to determine what kind of eruptions we can expect in the future.”
Source of news : Sciencemag