The volcanic activity in Mt. Aso caused a small earthquake in the area on the evening of May 3rd. It was the first such earthquake to be recorded in nearly 20 years.
Here’s a link to the TKU report from which the image was taken: http://www.tku.co.jp/web/news_article/阿蘇中岳%E3%80%80２０年ぶり火山性微動で震度１?iframe=true&width=560&height=420 or https://www.youtube.com/watch?v=JsWccZq99Ag
Here’s a link to another Japanese report with a video of a TV report: http://www.fnn-news.com/news/headlines/articles/CONN00291724.html