there are lots of earthquakes every day but these are so small. like literally undecectable by humans. the only reason we know they exist is because of extremely sensitive sensors. a small earthquake (about a 3 or 4) happens less than once a year. maybe once every two years. there hasnt been a big earthquake since 1989...
and tell her to move to south california because its the only part that gets any sun. people think San francisco is warm well it's not. average is 50 degrees.
I've lived in California for about 40 years, and I've been in two trimmers. The worst of it was when things rattled around enough that the noise woke me up in the middle of the night during the second one. That was about 30 years ago.
It all depends on where you live. For instance, don't live on or around the San Andreas fault line. If you live somewhere like Sacramento, you're pretty safe from Earth quakes.