I found this notable because it's the first time I've received a push notification in the U.S. about an earthquake, which I received about 10 seconds <i>before</i> the shaking started.
I’m in Nevada City, CA (~2.5hr northeast of SF) and saw the notification maybe 3-5 seconds prior. Everyone in my workplace stepped out of their offices and said they all saw the notification before the building started shaking.