Here’s a Japanese page with information about where evacuations have been called for.
http://www.anshin.pref.kumamoto.jp/osirase/index.cgi?type=1001
I don’t have time to translate in detail but I can say that the major areas involved are: Yamato Reihoku (in Amakusa) Misato Kosa Uki-shi Amakusa-shi
Even though I can read Japanese, it took me a while to click through all of the links on this page. I really feel that the prefecture needs to improve the way it puts out disaster information.