If you are ever around Memphis check out the bridges over the interstate (I-40). They have cable jumpers installed on all the bridge beams, apparently to prevent the bridges from collapsing in the event of an earthquake. I noticed it the last time I drove through there. It appears that a lot of money has already been spent on the earthquake that probably won't ever happen.....
I remember seeing some online reference material for that exercise; the expectation was that every river crossing between St. Louis and Natchez would be destroyed or suffer enough structural damage to close it for weeks, perhaps months. Casualties in Memphis were anticipated at 300K dead.