Petra:
1: To have a M9 you would have to break the entire Sam Andreas fault from Gulf of California to Mendocino....and because the San Andreas is steep to vertical and the part that would break only extends to about 15 km, and slip would only be 4 to 10 m, even then the magnitude might not make 9. Slip on San Andreas fault south of Palm Springs...if 300 years since last one and 20 mm/yr, would be about 6 m=20 feet. San Andreas in some areas can slip 10 m (33 feet), but 20 m is highly unlikely.

2: As for earthquakes last summer...that would be impossible/nonsense for obvious reasons.
Chris