Ontakesan, the second-tallest mountain in Japan, is clearing its throat.
This is possibly the most frightening video I’ve ever seen. If there had been fresh hot lava erupted, the ash cloud would have instantly incinerated the videographer and everyone with him.
A less-terrifying video of the mountain:
There’s a webcam here.
Update: vulcanologist Erik Klemetti comments.
They’re saying that a lot of hikers were on the mountain when it erupted, and at least 30 of them are dead.
http://www.cnn.com/2014/09/28/world/asia/japan-volcano-ontake/index.html