The snow-covered peak of the 2,402-foot (732-meter) Mount Usu erupted today, spewing black smoke and ash and forcing over 15,000 people from their homes. Historically one of Japan's most active volcanoes, Usu last erupted in 1978 after a number of earthquakes which formed a new and smaller volcano by its side. Mudslides triggered by that eruption killed three people in 1978, but so far no casualties have been reported from this eruption, which was predicted by experts. While volcanologists doubt that another major explosion will occur, they have not ruled out further activity. Another concern is mudslides, as the hot ash and smoke could quickly melt the mountain's thick carpet of snow.