That guy erupts a LOT, as in a few hundred times a year. Some say that it's really been in continuous eruption since the mid 50's but usually it's just gas that gets shot out. The ash "burps" can be interesting at times; it's fun to watch live!
I better get in here quick. The People of Japan are some of toughest People on earth. They have encountered many things that would have turned most countries upside down. No Volcano or tsunami will knock them down.