The strike slip nature of the San Andreas Fault zone in California precludes really big earthquakes. USGS thinks a 8.2 or 8.3 is about as big as they could get.

The strike slip nature of the San Andreas Fault zone in California precludes really big earthquakes. USGS thinks a 8.2 or 8.3 is about as big as they could get. The biggest historical California earthquakes have reached 7.9 in magnitude. (http://www.conservation.ca.gov/index/Earthquakes/Pages/qh_earthquakes_calbigones.aspx http://www.conservation.ca.gov/index/Earthquakes/Pages/qh_ea...)