Two days ago we stocked up on goods from Costco, and we have 120 liters of drinking water ready. Our grandparents in Chiba lost power in the last big typhoon and likely again today.
I hope the damages are not super severe, but with wind slamming our house like this no chance Tokyo is not going to have fallout.
JMA has it as two earthquakes about ten minutes apart. Link to the first one: http://www.jma.go.jp/en/quake/20191012092552393-12182205.htm...
"This earthquake poses no tsunami risk."
Also nothing here: https://ptwc.weather.gov/
A 5.0 in that area in the world is somewhat routine.
This time the only thing I prepared was not going out today and following the news closer. I prepared for the last typhoon and just left my stash in the same place permanently. I've got enough to live for 1 week with no problem (long-lived food, water, money, battery, etc).
Some exceptions/differences: 1st floor needs extra flood protection, for earthquakes make sure you know where the fire extinguisher is because fires are common, etc.
Same preparation: stay away of the big glass windows, follow the news closely, have enough to live for few days, check on friends and family, be ready to get out of the building ASAP if needed, know where shelters and safe areas are, etc.