It was actually 23km deep. The thing is, it was a 6.4 on the richter scale and 300km away. On the Japanese
Shindo scale, which measures the strength at the point it is felt, it would probably be a 3 or 4 close to the epicenter and maybe 1 or 2 in Vancouver. The Tohoku quake was a 7 in most of Tohoku and 5 in Tokyo. Even the aftershocks were rated as 6.
That's the problem with the Richter scale. It only measures the epicenter. So, if you felt it, you automatically feel like you survived a 6.4 magnitude quake... even though you were 300km away.
I experienced a 4.5 a few months ago in Japan, and it wasn't the kind that rolls, but the kind that goes BANG! and wakes you up in the middle of the night. Quite freaky, but it was more of a "wow, I feel really small and powerless" feeling to be honest.
To put that in perspective, that's about 100x smaller than the 6.4.
That's not to say we shouldn't care. If anything, it should motivate some to think about what kind of emergency preparedness they have ready when a large quake hits the region.