I'm going to visit my son in California and I have two things on my mind - earthquakes and drought. Both are the result of high-energy processes in our good old Earth.
The first is drought. California has had a very long drought so far. However, looking at tree rings and such, 100 year droughts are common, and very long droughts have wiped out ancient civilizations. It is the natural state of California to be a dusty desert, exactly like the southern deserts of Chile, which are lucky to see rain every 7 years.
So what could have fooled Mankind so much as to want to settle there? Nobody lives in the deserts of Chile. It's just that during our short historical period, we have had the benefit of a regular El Nino event every 7 years. The last train didn't come in, and California's lawns have to be painted green.
-to be continued, I have to make some illustrations.