Calaveras Fault 6.5 that occurred in 1911 in the Morgan Hill area. The most recent of these was a magnitude 6.2 earthquake near Morgan Hill in 1984. A magnitude 5.6 earthquake occurred on the Calaveras Fault on October 30, 2007 at 20:04 PDT (October 31, at 03:04 UTC), near Alum Rock. Prior to the 2014 South Napa earthquake, it was the most powerful quake to hit the Bay Area since the Loma Prieta earthquake of 1989, and the largest on the Calaveras Fault since 1984. Although it has been known for some time that the Calaveras and Hayward faults merge in the
1989 Loma Prieta earthquake the normally crowded freeways contained unusually light traffic. If traffic had been normal for a Tuesday rush hour, injuries and deaths would certainly have been higher. The initial media reports failed to take into account the game's effect on traffic and initially estimated the death toll at 300, a number that was corrected to 63 in the days after the earthquake. After the 1989 Loma Prieta earthquake occurred, a group led by Antony C. Fraser-Smith of Stanford University reported that the event was preceded by disturbances in background magnetic field noise as measured by a sensor placed in Corralitos, California,