Previous posters are all spot-on regarding surviving the quake itself.
Cover your head, with ANYTHING. being under a table or bed may keep a beam from breaking your back or shearing off a limb. Door jambs tend not to
pancake along with the rest of the floor, so you could avoid the free-fall drop, and then climb down on the debris. Most of the survivable injuries
are from falling flying small debris, not taking a girder up your nose or something.
The killer is the aftermath.
First comes fire.
Severed gas mains, downed electrical lines, food cooking that now spills all over a wall and floor and sets fire kitchens all across the city.
Next threat is dust.
Every particle of dust that has been settling in your building since it was erected is now airborne. The dust will get in your eyes, make you cough
and gasp for air, inhaling the particles deep into your lungs. Everyone in refugee centers will have the same problem, making respiratory outbreaks
inevitable as you all cough on each other.
Third is shifting debris fields.
Even without a single aftershock (almost impossible), the piles of ruble will be continuously settling over the next week or two. surfaces that you
assume are solid, like a roadway or a stairwell, could actually be a teetering, temporary bridge that is ready to collapse like it was in a
roadrunner-and-coyote cartoon. Most of the dead will actually have died of their injuries while trapped in debris, rather than from the blunt-force
traumas administered by the quake itself.
How do you prepare?
You need the same equipment you'd need after a tornado that topples buildings, or a hurricane, or a bomb blast.
Nuisance Level dust mask / N95
knee pads & work gloves, work boots
winter-weight clothing (protects the rest of your body from falling debris
a helmet (any will do, hard hat makes the most sense, and inexpensive, tho a bike helmet would work ok)
And then the stuff you need for "salvage" of necessities following civil unrest:
50'-200' ft of rope
small "bottle" hydraulic jack
basically, a kit like fire fighters would use. You'll probably be doing a fair amount of that as well.
edit on 24-11-2018 by Graysen because: I'm just so full of ideas!