Glossop, 10 miles east of Manchester, an insomniac HuwG was violently shoved in the back while watching a video. To and fro movements continued for about 10 seconds, maximum amplitude about 2.5 inches.

Somewhere inside me a geology graduate reasoned that, even if I hadn't felt or paid attention to any preceding p-wave event (which is like a single sharp tap with a hammer) this was an earthquake. Also, I realised the direction of movement was N-S, with no vertical component, making it G_s (or "Ground Shake") waves. (Any vertical component means G_r or "Ground Roll".)

Once I'd checked that the scaffolding around the terrace house next to mine (they are fixing the roof and gutters) wasn't likely to totter into the street, I went back inside and listened to the news. The motion of G_s waves is perpendicular to the direction of travel so either Manchester had been very comprehensively feng shui'd or the epicentre was due east of me - which of course was the case.

10km is quite deep for an earthquake focus. I'm prepared to bet that it will be movement within Jurassic sediments on older Hercynian (Devonian and Carboniferous) structures.

Having royally annoyed all 'Catters with my smug demonstration of the "in" terms, I will say I was concerned, though not panic-stricken. Hanging lights swung and car alarms went off but no serious damage.