Surprised about the construction especially since the earthquakes are frequent and can be bad.  

The recent earthquakes destroyed many multi-family complexes and will continue doing so.

Separate issue is only 13% of CA homeowners pay for earthquake insurance because it's so expensive and the deductible can be really high.What are your re-building costs in your area?

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).

The house had some signs of foundation settlement when he bought it which were chalked up to age, however it’s clear now that there has been more recent movement (some of this may have been due to an earthquake a few years ago) causing about 3 inches of settlement along this very small house.   

I have been in a 6.8 and 6.9 earthquake in WA and CA respectively.

Even though we live in earthquake country, this was a new experience for us.

Much of the country is at high risk between fires, hurricanes, tornados, tidal waves, earth quakes, rising tides, etc.  

For example, in California, we have earthquake and foundational issues.

Earthquake, is not offered if you are in a fault zone.e.