Which area of the north american continent would have the greatest risk of earthquake damage?

The area is California.

There are 500,000 seismic tremors occurring out of which most of them are in the California zone. Over 80% of seismic tremors happen in a territory known as the Pacific Ring of Fire, a 25,000-mile horseshoe shape along the north side of the Pacific Ocean.  

The principle purpose behind the distinction is that the California coast is directly over the limit of two of the structural plates that make up the Earth's covering.  

Earth's covering, the lithosphere, is separated into in excess of twelve strong plates that buoy over a progressively gooey layer of hot shake.  

In California, plates are granulating against one another. Envision striking two blocks against each other, often as possible reason them to split, perhaps severing lumps. As increasingly more weight is included, the block is probably going to break someplace in the center.