What caused the volcanic area in Northern California?

Question

I know there are a lot of fualts in the bay area but what caused it to have so many eathquakes occur in northern california?

Answer 1

Tectonic movement. The Pacific plate is part of the "ring of fire" it is constantly moving north and south and eastward as it folds under California. that movement causes your earthquakes and leaves a seam for magma to leak to the surface forming volcanic eruptions, sea mounts, vents, and volcanos.