Last night, the largest earthquake since 1984 struck Britain. There I was, sleeping, like any good scientist should be at that time of the day (unless they're writing a PhD) when I was woken by the bed shaking. Sometimes this is because of the enthusiastic couple who live in the flat upstairs, but this was different. The room shook for probably 20 to 30 seconds, accompanied by a low rumbling, and I realised it was probably an earthquake. I checked the time so I could look at the BGS website [pdf] this morning: it was 1am.
This morning I discovered that it was a magnitude 5.2 quake, with the epicentre near Market Rasen, Lincolnshire. 5.2 is a pretty hefty magnitude, and it's fortunate that the focus was 10 km deep; if it had been much shallower it could have caused a lot of damage. There was only one injury, a man in Wombwell, near Barnsley, who was hit by a falling chimney pot. As the man's father said 'of all the things to happen-an earthquake!'
If you felt the earthquake, the BGS have a questionaire to fill in. It only takes a few minutes, and they use the information to do science.
As far as the Earth's crust goes, the UK is pretty stable, but earthquakes are not that rare. They just tend to be small. The BGS has a list of earthquakes for the last 30 days here. You'll notice that there has been aftershock, magnitude 1.8, from the Market Rasen quake.
The BGS now reckon that the depth of the main earthquake was more than 18 km. There have now been three aftershocks, with the largest at a magnitude of 2.2.