Side note. We lived in San Francisco when this one 6.9 hit. NO Warnings at all. Most buildings and infrastructure had been built/upgraded for earthquakes yet the damage was pretty bad.
https://en.wikipedia.org/wiki/1989_Loma_Prieta_earthquake
I can't imagine what a 7. would do here.
https://en.wikipedia.org/wiki/1989_Loma_Prieta_earthquake
I can't imagine what a 7. would do here.