My understanding is there is always “massive” activity on the ring of fire, that just goes with the subduction. The plates that form the two sides of the San Andreas fault are moving lateral to each other, not one under the other like most of the ring of fire. The San Andreas blows off a big quake every 150 years or so. The last big one along the SA fault in Northern California was the 06 San Francisco quake, and in Southern California it was the 1857 Fort Tejon quake.
California is due for a big one on the SA, regardless of what is going on around the Pacific.
It seems that the scale(richter) scale of these earthquakes is huge. Quite a few 7s or higher. Seems unusual, but I could be wrong.
Very interesting about 1857 Fort Tejon quake.