From Reuters:
Japanese volcano kills one, over 30 seriously injured
A Japanese volcano popular with hikers erupted on Saturday, killing one woman and seriously injuring more than 30 people, officials and media said.
The mountain draws walkers who come to admire the autumn colours on the trees.
"It was like thunder," a woman told public broadcaster NHK of the first eruption at the volcano in seven years. "I heard boom, boom, then everything went dark."
The Japan Meteorological Agency said the volcano, Mount Ontake, which straddles Nagano and Gifu prefectures 200 km (125 miles) west of Tokyo, erupted just before midday and sent ash pouring down the mountain's south slope for more than three km (two miles).
Reports of more than 250 people stranded on the peak. This was a very popular hike, especially now with the fall colors. Really surprised that there was no prior detected seismic activity.