During the 70's, I worked for SCE as a design draftsman. I worked on the Mammoth Lakes Project back then. One of my best friends was in the Seismic Studies Group.
Mammoth Lakes area is not a big problem (sorry about that for all you California haters)
The big problem is a fault that lies 35 miles underneath Newport Harbor. When that one goes there will be major death and damage.
I also worked on SCE's nuclear generating plants; San Onofre and Diablo Canyon. The cooling radiators extend about a third of a mile off shore.
No amount af concrete and rebar is going to keep them intact if the quake hits 8.0 or higher.
Nuke plants have triple redundancy in their systems. But there will still be leakage, the current flows south along the California Coast and anything south will be in severe danger.
And if all three systems fail, the reactor core will "china out", and depending on which way the wind blows that day, an area the size of Pennsylvania will be affected.
Eventually, Los Angeles will be across from San Fransico, as everything on the westside of the San Andreas Fault slides north an shears off. There should be about a 50-70 mile channel between them.
IIRC the time frame for this is about 100,000 years.
California was a great place to grow up in. (I grew up in Burbank, right next to Lockheed, where my parents met on the P38 assembly line in 1943)
California has been ruined by idiot politicians and other "non compos mensits" who came from other parts of America.
So, don't sweat Mammoth.
LtngRydr