Backgrounder: Assessing the West Coast volcano situation

According to Jackie Caplan-Auerbach, associate professor of geology at Western Washington University, there are about a dozen volcanoes between northern California and southern B.C.

The "Cascade Volcanic Arc," as they're collectively called, has been created by the Juan de Fuca plate sliding under the North American plate.

"That's why all of our volcanoes are sort of in a line at a certain distance from the coast," Caplan-Auerbach said.