video explanation here:
After watching Sakurajima Volcano erupt daily for months on end, I noticed a NEW spot erupting smoke/steam on the back side of the mountain… this has now progressed into a full blown large venting — possibly the formation of a new caldera, or a second smaller cone.
This does not happen every day on such a large scale.. worthy of note for sure.. and nothing on the net about it yet from the Japanese agency.
Screenshots — October 11, 2011
original video: