When an earthquake strikes you have two major things to worry about:
First, things may move or fall over. This could mean glasses falling out of cupboards, or electrical appliances crashing to the ground (fire hazard) or even the hot water tank tipping over (fire hazard again).
Second, the house itself may walk away from its foundation, or the second floor can slide sideways right off of the first.
To protect against the first danger, you can have cupboard doors with positive latches, any hardware that latches the doors closed. There are special straps to attach electronic equipment to their tables. You can strap the hot water tank and brace it to a post in the basement.
For the second danger, there are all kinds of attachments that can be used to structurally tie the house to the foundation, and the frame of one floor to the frame of another floor with far more strength than regular construction. These can even be put in an existing home to make it earthquake ready. In the Vancouver area, where a major quake is expected within the next 30 years, you will find specialized earthquake readiness contractors who can do all of this for you.
The products we showed were made by Simpson Strong Tie. The "earthquake preparedness contractors" we had on the show were from Terra Firm in Vancouver.