So let's say there is an earthquake and your house is a total loss. You owe 350,000. The cost to rebuild is 300,000 (you pay some for the land, often times what you are insured for is less than what the house and the land are worth). Your deductible is 100,000. So you have no house, a mortgage for 350,000, a check from the insurance company for 200,000 that usually goes to the mortgage company, not you, and it will cost 100,000 to rebuild. Some people could get a loan for the 100k, but most people couldn't. So you paid all those years several extra thousand dollars a year for your insurance company to send 200k to your mortgage company. And that's IF they do cover it, because like I said, if the pipes burst, they won't consider that earthquake damage, it's flood and so on. There's a ton of loopholes so they can get out of it. They're like Insuracare in The Incredibles.
It's the exact same thing with flood insurance, except you can buy in to a government flood insurance program. I don't believe there is anything like that for earthquakes. You're really better off spending that money putting in structural supports in your home that will withstand an earthquake because earthquake insurance is a scam.