Welcome to the Shaky State. 8.1 is absolutely brutal. Contrast that with the Loma Prieta quake in 1989 that shook San Francisco (7.1), or the Northridge quake that caused tremendous damage in the LA area in 1994(6.7). A quake of the magnitude under discussion here is equivalent to the 1906 San Francisco earthquake that essentially leveled the place.
Don't be standing nearby when it lets go.