Must have been a slow news day. The scenario analysis for a Cascadia quake was updated last year:[www.crew.org]. It triggered a bunch of articles at the time. Keeping the interest up is good, though, so people don't get too complacent.

Reading between the scenario lines, it's clear that effects of a big quake would extend well beyond the immediate shaking damage zone and tsunami. A big quake like that triggers other quakes, and smaller faults could pop that are closer to major populated areas. A smaller (but still 5-6ish) aftershock near you can cause more damage than the larger quake farther away - ask Bakersfield in 1952. And the shaking is likely to be felt, if not damaging, far beyond the Pacific NW - probably well into Central California and parts of Nevada. Then, as was touched on in the scenario, there's the economic and social effect: many areas will have supply lines cut off when the ports and refineries are wrecked, the financial system will take a whack, and emergency support will be needed from a wide area. I wouldn't count on much from FEMA, though - regional mutual aid would be more reliable.

Much the same effect would occur with a Big One in California, which historically is more likely to have one - recurrence intervals in the 100-200 year range rather than 300. Typical CA big quakes would be smaller (subduction quakes produce more energy than strike-slip) but something in the 7's near SF or LA would produce several billion$ damage too.

What's the worst case? Hmmm ... Cascadia quake triggers a San Andreas system quake in BA or LA, which soaks up California resources when they're also needed to the north? Could happen - both systems are in their respective windows for another large quake.