I told somebody to look this up in my past writings, but they couldn't find it. God knows I never look in the old bog attic! So, I thought I'd whip it up again, from scratch. First, a note on probability: The odds of a big earthquake hitting Toronto aren't any worse than an M6.3 hitting any other 'hotspot' in Eastern North America. It's just that I live here. And the odds for a major urban disaster are the same for any city, hovering at one in ten thousand per year. So, if you were rolling a ten thousand sided die every year, you would hope the red face didn't come up! There are probably a lot less sides for the Toronto Earthquake die.
Be aware of your surroundings! Nine tenths of your seismic hazard has to do with what's around you, and not the regional geology. There are huge amplifications with soft ground that negate the difference between Toronto and Los Angeles. Are you on hopeless soft ground? Do you have an old brick house with no mortar in the chimney?
The big hazard will be bricks falling on you. Be ready to stand in the doorways until everything falls. Do not have heavy things over your bed, like trophy cases. Be prepared to see all your Royal Dalton shattered.
If you feel industrious, you can fix things up beforehand, like getting mortar, but what the heck!
Be prepared for after the earthquake. Lots of aftershocks, stay away from the bricks. Life is not going to be happy for 3 to 5 days. Toronto doesn't have a clue what to do. Have a radio to find out what they are blaming everything on! Maybe there will be shelters, but expect the water, power, and gas to be off. Makes for a fun January! Help will rush in from surrounding areas, but you are going to have to camp for a few days, since I can't imagine the shelters will in good shape. No evacuating either, since there will be no place to go, and the bridges are going to be buggered. If you are on the 50th floor of a high-rise, you can watch all the fires below, and be prepared to walk a lot of stairs!
Even the worst scenario only has a few dozen killed, since most housing stock will ride it out. So keep your emergency kit ready!
Added note: As pointed out to me, the doorway bit is not the latest 'thang' from California. It's just that I don't expect 1 m/s motions in Toronto, and there really aren't good tables to duck under in every room. If you missed the P-wave and are being hit by swamp-waves, go to the floor right away and cover up.