The latest earthquake to strike the US is, like most of them, associated with the Juan de Fuca plate. This one is the biggest so far and was very near to Mt. Shasta, an active volcano of the Cascades system. There are no fault lines near where this latest shake occurred. But if we look at earthquake maps, we can see clearly over time that the quakes are growing rapidly in number and violence. The section of the San Andreas between LA and San Jose is nearly totally frozen and doesn't even have micro shakes: a very bad sign. The Juan de Fuca plate is directly responsible for volcanic activity as well as a springboard for great quakes to the south. Also, the hinge between North and South America has been hammered by significant but sub-7.0 mag quakes this past month. The chances of a major event rises.