Don't think you can get away with it

Your reasoning for claiming refund is 突发事件. And your consern over earthquake will not qualify.

In Nevada and California, earth quake happen everyday and buildings and cities are built to withstand the shake. So unless it is disastrous, the agent won't consider it as 突发事件 based on your fear.

You can still fight it in small claim court, but the chance of you winning it is very very small. When you think it is unsafe to travel, it is your call. Sometimes you are thinking too much, and some other times you may escape from big trouble. Nontheless, you should be paying for your personal decision.

Just my 2 cents