We'd experienced the Sunday earthquake but I'd just thought it was the subway as the London subway can be felt rattling along underground when walking around the city. But a friend who is currently working in Tokyo and who had offered to show us round, pointed out that we were standing on a bridge across the river and there was no subway there. The news the next day confirmed it was a 5.1 quake. But on our last night it is no exageration in this article that the buildings in central Tokyo shook. We had chosen that night to have a meal and drink in the hotel bar on the 51st floor. There was a deep rumble and the building started to sway and shake. The fact that I'd already had a Martini and a glass of wine left me quite calm... that, and the fact that the majority of people in the bar were Japanese and seemed quite non-plussed about the whole thing... but us weedy westerners looked around at each other with raised eyebrows wondering whether we should be running. It seemed to go on for quite a time but in reality it was probably less than a minute. No doubt some of you have experienced far worse but for us Brits these natural threats are quite alien and pretty scary.
Update: I should say that we do get earthquakes in the UK and have had some at 5.5 ish. However they are very, very rare.