Just released this morning, an epic USGS disaster scenario on a 200-mile rupture of the San Andreas Fault in southern California. This is regarded as the most likely next "Big One" in southern California. The report looks very comprehensive and I plan on reading it in the next week.

Summary (including shake map)
http://pubs.usgs.gov/of/2008/1150/

The full report (over 300 pages)
http://pubs.usgs.gov/of/2008/1150/of2007-1150.pdf

Press Release
http://www.usgs.gov/newsroom/article.asp?ID=1947&from=rss_home

USGS also today issued new materials on the Bay Area's Hayward Fault.
www.usgs.gov

Our goal in the ShakeOut Scenario is to identify the physical, social and economic consequences of a major earthquake in southern California and in so doing, enable the users of our results to identify what they can change now—before the earthquake—to avoid catastrophic impact after the inevitable earthquake occurs. To do so, we had to determine the physical damages (casualties and losses) caused by the earthquake and the impact of those damages on the region’s social and economic systems. To do this, we needed to know about the earthquake ground shaking and fault rupture. So we first constructed an earthquake, taking all available earthquake research information, from trenching and exposed evidence of prehistoric earthquakes, to analysis of instrumental recordings of large earthquakes and the latest theory in earthquake source physics. We modeled a magnitude (M) 7.8 earthquake on the southern San Andreas Fault, a plausible event on the fault most likely to produce a major earthquake. This information was then fed forward into the rest of the ShakeOut Scenario.

The damage impacts of the scenario earthquake were estimated using both HAZUS-MH and expert opinion through 13 special studies and 6 expert panels, and fall into four categories: building damages, non-structural damages, damage to lifelines and infrastructure, and fire losses. The magnitude 7.8 ShakeOut earthquake is modeled to cause about 1800 deaths and $213 billion of economic losses. These numbers are as low as they are because of aggressive retrofitting programs that have increased the seismic resistance of buildings, highways and lifelines, and economic resiliency. These numbers are as large as they are because much more retrofitting could still be done.