A swarm of earthquakes that rattled the Salton Sea area earlier this week has increased the probability of a major quake hitting Southern California. The California Office of Emergency Services (OES) issued an earthquake advisory warning residents and officials in Ventura, San Diego, San Bernardino, Riverside, Orange, Los Angeles, Kern and Imperial counties that there was a greater possibility of a major earthquake through Oct. 4. ... The swarm occurred in a region known as the Brawley seismic zone, which is located near a fault network that connects the southernmost end of the San Andreas fault with the Imperial fault....