According to an article published on the Scientific American website last year, the increased volcanic activity we are seeing throughout Japan (and, of course, including Mt Aso) may be related to the 2011 quake:
“Japan’s massive 2011 earthquake may trigger more, and larger, volcanic eruptions over the next few decades, perhaps even that of Mount Fuji - but predicting them remains close to impossible, a volcano expert said on Friday.”
http://www.scientificamerican.com/article/japan-s-volcanoes-made-more-jittery-by-2011-quake/
