2007 Alum Rock earthquake 2007 Alum Rock earthquake The 2007 Alum Rock earthquake occurred on in Alum Rock Park in San Jose, California. It measured 5.6 on the moment magnitude scale and had a maximum Mercalli intensity of VI ("Strong"). The event was then the largest in the San Francisco Bay Area since the 1989 Loma Prieta earthquake, which measured 6.9 on the moment magnitude scale, but was later surpassed by the 2014 South Napa earthquake. Ground shaking from the Alum Rock quake reached San Francisco and Oakland and other points further north. Sixty thousand felt reports existed far beyond Santa Rosa, as far
1989 Loma Prieta earthquake oblique reverse faults and were within of the M6.9 Loma Prieta mainshock epicenter, near the intersection of the San Andreas and Sargent faults. Total displacement for these shocks was relatively small (approximately of strike-slip and substantially less reverse-slip) and although they occurred on separate faults and well before the mainshock, a group of seismologists considered these to be foreshocks due to their location in space and time relative to the main event. Each event's aftershock sequence and effect on stress drop was closely examined, and their study indicated that the shocks affected the mainshock's rupture process. Following the August 8,