The Forecast: Each year, about 60 of the world’s 1,500 potentially active volcanoes blow. Most produce only a weak sputter, but occasionally a peak goes big: Iceland’s Eyjafjallajökull halted air travel in Europe for six days last year with its six-mile-high ash plume. Domestically, scientists fear that magma movements below Mount Rainier could unleash mudslides on Seattle’s suburbs.
Stats: 169—the number of active U.S. volcanoes.
Worst-Case Scenario: Being anywhere near an eruption is obviously bad, but the extended zone of the ashfall can be just as deadly. Goggles, masks, and long sleeves are a must. Ash also needs to be cleared off structures as soon as it’s safe—roof collapse caused by saturated ash is the most common killer in eruptions.
The Smart Play: Going hiking near a volcano? Listen to your guide. In much of the world, experts aren’t equipped to predict volcanic activity, so researchers like Robert Buchwaldt from MIT are teaching locals to identify natural eruption cues. Examples? “Swelling in certain portions of the volcano, big cracks forming, and plants around the volcano drying up.”