Don't let it get in the way of your deal if the house is nice otherwise....property is in California and will need Sesmic retrofit for earthquakes.

If not a typical earthquake or flood area then insurance likely cover that provision nor does tenant reimburses for that. 

Does the building code in regards to earthquakes have any bearing?

Here in California we see foundation issues all the time, especially because of earthquakes and soil movement.

This leads to a slow or stagnant increase in property prices and rents in established areas as people move further out and rent or buy newer homes.Natural disaster risk - Natural disasters such as tornadoes, hurricanes, and earthquakes destroy communities.

If you think it’s difficult in a landlord friendly state with low property tax, low insurance costs, no state income tax, no earthquakes, no tornadoes, no snow, no hurricanes, stucco siding and tile roofs, a very “young” property inventory, below average housing costs, and renters who make good money. 

Or, a charging order may be granted.If you're going the umbrella insurance route, perhaps see if it will cover you for several things including just the routine slip and fall (like mold or earthquake).

In California where I'm at, because of earthquakes, retaining walls that are on a steep grade, have structures within a certain distance, higher than 36" (or 42 maybe, can't remember) all require a permit.   

Account ClosedIn light of recent earthquakes, and the fact that experts predict the "big one" is coming to the Hayward Fault Line, would you consider seismic retrofitting a necessary capital expenditure? 

Earth quakes in CA, Tsunami in Thai land, Hurricanes in Gulf coast.