Ok, so the one good thing about living in a wooden construction, old school apt. building is that you feel the earthquakes like the one that just happened, early. Basically, if it feels like someone has a power buffer on oak flooring below you, an earthquake is about to hit. Sitting on the tatami you really get the early warning system. I was on my feet and on the way to the kitchen before it really started to shake. I enjoy the false sense of security which allows me to forget how overdue Tokyo is for a big one.