earthquake

We experienced a nice little earthquake a little over two hours ago (here). Epicentred about 60km north of Ottawa, its estimated magnitude is 5.0.

Fittingly enough, I was sitting at my desk reviewing and tweaking some earthquake procedures when it happened. My home office being well above grade, the movement was considerable, so I scooped up the dog and headed for the basement. The shaking lasted at least 15 seconds.

I recall my only other earthquake experience (as far as I can remember). I was at work, sitting in the Langley BC office on the 2nd floor of a building of crappy construction. The place swayed like the dickens. To discourage us from running around or doing anything else untoward, our boss yelled at us to get underneath our desks. (I wonder how many people did that in Ottawa today?!)

The 2001 quake was 6.8 in magnitude, which on the logarithmic scale is 60 times greater than a 5.0. However, it was epicentred an hour south of Seattle WA, and at the distance from which we felt it, it was around a 5 for us. It felt worse than today's, but it definitely makes a difference what kind of building you're in and on what floor.

Ottawa is in the Western Quebec Seismic Zone, which actually has a quake every 5 days or so but they're not usually too big. Between 1980 and 2000, only 16 quakes were 4.0 or greater in magnitude. A 4.0 is 10 times less powerful than today's quake; it might be felt but is unlikely to cause any damage.