I found the official English page with information about the various quakes. One interesting point is that, although 7 on the Japanese scale was registered in Mashiki, there are no reports of 6+. The next highest intensity rating is 6-. The part of Kumamoto where I live (near Oe) was 5+.
– Kirk
http://www.jma.go.jp/en/quake/6/20160414213615395-142126.html