Which turned out not to be so serious, but it was a good jolt about 17:30. Same fault as the bad one a year and a half ago, off the Pacific coast. And we'd just had a good jolt at 5:30 this morning.
My train came to a stop in a station after everyone's cell phones had gone off with the warning, which I have long turned off: it never rings early enough to allow me any time, and it goes off far too often to be taken seriously. Gave the train and station on the elevated platform a good roughing up, but we eat quakes like this 'for breakfast and shit them out before lunch'. All I learned from the big one was to get a message home before the lines were swamped, and to start thinking about how I would walk home from where I was. Trains started again.
If you are new or coming to Japan, do not live near the coast or on landfill, or in a place more than thirty years old (new codes since). In Kobe '95 people died in collapsed buildings and fires from kerosene space heaters; in Tohoku '11 from the tsunami. Other than collapsible buildings or the sea side, your survival odds are high. You will face infrastructure fragility. Figure out your own food and water, and how you are going to get around in case of the worst. And never buy real estate here! Besides the fact it is already depreciating, and the bust is yet to come, Tokyo will get flattened yet. If you live, there is no good reason to still owe money to the bank.