I'm going to partly deliberately not answer your questions (in case you sue me if I say something and it turns out to be bad advice). But, I don't see any reason why the southern San Andreas fault could not break in a quake approaching M8...all the way from Salton Sea up to the base of the S. B. Mountains where you are or even farther up to Wrightwood, where we are going on a field trip tomorrow. But, someone might want to link to Jim Brune and precarious rocks....there was a talk here today on that...where there are delicately balanced rocks located, for example, half way between the San Andreas and Sam Jacinto fault...showing that there had not been especially strong ground motion. Brune has a poster on shattered rock...which is located in the hanging-walls of thrust faults in certain places. It is possible....but this is not directly my field, that you could have stronger ground motion from a thrust earthquake uplifting the San Bernadino Mts...or from a local earthquake like Big Bear, than from a San Andreas, say, M7.7 or 8...you might want to get ahold of papers by Brune and see if there are any delicately balanced rocks in your area. As for insurance..this always depends on cost, deductible, risk, your ability to not be wiped out...no one can answer that question for you.

In case you do want to sue me, I am not the real "chris in suburbia" but am instead an imposter. or, maybe I am the real one. Or, maybe he or she does not exist.
Chris in Palm Springs