Four years after Iceland's Eyjafjallajokull volcano seriously disrupted aviation, another tongue-twister may be set to blow. Iceland's meteorological office says the area around the Bardarbunga volcano has experienced its strongest earthquake since 1996 and there is a chance the "current activity will result in an explosive subglacial eruption, leading to an outburst flood and ash emission," the BBC reports. The threat level for air traffic has been raised to orange, the second-highest level.
Iceland says "intense seismic activity" began in the glacier-covered area on the weekend, with a swarm of more than 1,000 earthquakes. Roads in the area have been closed as a precaution against the glacial outburst flood likely to occur if there was an eruption, reports Wired, which notes that the volcano has a long history of eruptions: Its last confirmed eruption was in 1794, but around 8,600 years ago, it was the source of the largest lava flow in the modern geological epoch.