[dribnet]

"Elsewhere in northern California, a major earthquake along the subduction zone between Cape Mendocino and Vancouver Island—a region known to geologists and seismologists as Cascadia and which the Working Group gave a 10% chance of rupturing in the next 30 years—will almost certainly be followed within decades, perhaps even within hours, by a major earthquake along the northern segment of the San Andreas."

Notable that Sunday evening there was a 6.9 quake in that region which was the California's largest in the past 7 years. I believe a deformation (not a rupture) - but it was just south of Cascadia near where it meets with the San Andreas fault close to the Mendocino triple junction. [1]

[1] http://www.decodedscience.com/m6-9-california-earthquake-lar...

[cossatot]

Actually, all earthquakes are ruptures in the sense that they represent slip (displacement) on a surface. Oftentimes, though, geologists and geophysicists will refer to ruptures as the surface break of an earthquake (where the slip on a fault reaches the earth's surface), so some context is required to distinguish between the two.

The recent M 6.8-6.9 event occurred offshore, so it's not entirely clear whether it broke the surface. Most earthquakes below M 6 don't, and most M7 do (if they occur in the crust).

The focal mechanism of the earthquake [1] (see how to interpret them at [2]), which shows (among other things) the pattern of stress change during faulting, does (from my visual inspection) indicate that the Coulomb stress change on the subduction zone north of Mendocino. I'm not sure what the implications are for the northern San Andreas, which may not be optimally oriented to receive additional shear stress from this event, but I think the earthquake might have released some of the normal stress that keeps the fault from slipping there.

[1]: http://earthquake.usgs.gov/earthquakes/eventpage/nc72182046#...

[2]: http://earthquake.usgs.gov/learn/topics/beachball.php