Your job sounds like mine was around 1999-2000, flying to San Francisco every 4-6 weeks for either a one or two week stint.
I never used to stay in San Fran itself, I used to go south down 101 to the Palo Alto area. One night I was woken up at about 3am by a low rumbling sound and various bits shaking. I was so knackered that I didn't really wake up fully and thought that it was a goods train rumbling past (Tip: If you're going to stay in the Hyatt in Palo Alto, always ask for a garden side room because there's a CALTRAIN track just the other side of the car park on the other side).
Then I realised that trains don't run through the night on this track, and it's a passenger line not a goods line, and I WAS on the garden side of the hotel. I'd experienced my first earthquake.
Sure enough the next morning's breakfast time TV had it on the news as a 5.7 quake, but the epicentre was around 60 miles south of Palo Alto down past Gilroy. Makes you realise the power these things have when the earth moves for you from 60 miles away.