The Cascade volcanoes do not share a common magma chamber and there's no particular increase in the chance one volcano in the Cascades erupts if another is erupting.
And of course the San Andreas has nothing to do with Cascades at all.
"And of course the San Andreas has nothing to do with Cascades at all.
"
Keerect! But what's a little accurate information? Heck, we can scare everyone on the West Coast if we want to. Feh! I grow weary of people who know absolutely nothing about geology or earthquakes who come on these threads and say exceedingly stupid things.
It is not that far fetched to suggest that movement of either the North American Plate or the Pacific Plate could result in both increased earthquake along the San Andreas and movement of magma to the surface in the Cascades. Both volcanoes and earthquakes are a result of tectonic activity.