I found this part of the article somewhat confusing:
In 2001, the two scientists discovered that the Juan de Fuca plate was slipping under the North American plate, which stretches down to California.

Was there ever any doubt that the Juan de Fuca was subducting under the North America plate? And... Doesn't the North America plate stretch down a bit further than California? Hmmm... What am I missing here?

Canie