Here’s Joha. Here’s an online Hazardmap provided by Kumamoto prefecture. To be prepared for a network breakdown an offline one would make more sense, yet, I thought this one might be better than nothing. https://portal.bousai.pref.kumamoto.jp/?p=hazard&ll=32.637061996573436%2C130.77850341796875&z=9 As an advise it might be good to know the exact locations of evacuation shelters (multiple is better) in your surroundings and possible safe routes to get there. Such shelters can have different purposes (tsunami, fire etc.) so make sure to choose the right ones. Last but not least, in case of evacuation keep your stuff at a minimum (ID card etc.) to maintain mobility. It’s also good to prepare a Rucksack or similar handy carry bag in advance. There are numerous sites for foreigners providing infos on disaster preparedness. A good choice is the Tokyo Fire Department. https://tokyo-resilience.metro.tokyo.lg.jp/assets/pdf/DisasterPreparednessTokyo.pdf Stay safe folks!