Several long term forecasts for a large shock along the San Andreas Fault in that area had been made public prior to 1989 (the event and its aftershocks occurred within a recognized seismic gap) but the earthquake that transpired was not what had been anticipated.

The advisories following the two Lake Elsman events were issued in part because of the statements made by WGCEP and because they were two of the three largest shocks to occur along the 1906 earthquake's rupture zone since 1914.

Unlike other nearby (high gain) seismographs that were overwhelmed (driven off scale) by the large magnitude mainshock, the four accelerometers captured a useful record of the main event and more than half an hour of the early aftershock activity.

More moderate damage resulted from the August 8, 1989, shock (intensity VII, Very strong) when chimneys were toppled in Cupertino, Los Gatos, and Redwood Estates.

The significant amount of vertical displacement in 1989 was a key aspect to consider because a long-term sequence of 1989-type events (with an 80–100-year recurrence interval) normally result in regions with high topographic relief, which is not seen in the Santa Cruz Mountains.

[26][27] After the 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, about 4.5 miles (7 km) from the epicenter.

[28] The Fraser-Smith et al. report remains one of the most frequently cited claims of a specific earthquake precursor; more recent studies have cast doubt on the connection, attributing the Corralitos signals to either unrelated magnetic disturbance or,[29] even more simply, to sensor-system malfunction.

[30] The earthquake caused severe damage in some very specific locations in the Bay Area, most notably on unstable soil in San Francisco and Oakland.

Major property damage in San Francisco's Marina District 60 mi (97 km) from the epicenter resulted from liquefaction of soil used to create waterfront land.

[41] About an hour and 40 minutes after the quake, Fox affiliate KTVU resumed broadcasting, with their news anchors, Dennis Richmond and Elaine Corral reporting from the station's parking lot.

[43][44] KCBS-AM (CBS News Radio) switched immediately to backup power and managed to stay on air despite a subsequent generator failure.

[46] (All four network-affiliated TV stations (KRON, KGO, KTVU and CBS affiliate KPIX) would recover enough to broadcast continuous breaking news coverage of the aftermath of the quake for the next several hours, some of it picked up and broadcast nationally over their respective networks, as well as on CNN, in a manner anticipating later major catastrophes such as the 1994 Los Angeles earthquake and the 9/11 terror attacks).

[22] The Marina district was built on a landfill made of a mixture of sand, dirt, rubble, waste, and other materials containing a high percentage of groundwater.

At the intersection of Beach and Divisadero Streets in San Francisco, a natural gas main rupture caused a major structure fire.

[58] Immediately, a number of civilians began to free victims from the rubble of Ford's Department Store and the Santa Cruz Coffee Roasting Company – both buildings had collapsed inward on customers and employees alike.

[60] The civilians who were helpful initially, were soon viewed by police and fire officials as a hindrance to operations, with frantic coworkers and friends of a coffee house employee thought to be trapped under the rubble continuing their efforts in the dark.

[63] In other Santa Cruz and Monterey county locations such as Boulder Creek and Moss Landing, a number of structures were damaged, with some knocked off of their foundations.

A miscommunication made by emergency workers at Yerba Buena Island routed some drivers the wrong way; they were directed to the upper deck where they drove eastward toward the collapse site.

The added elements were longitudinal restraints at transverse expansion joints in the box girder spans, but no studies were made of possible failure modes specific to the Cypress Viaduct.

Nearby residents and factory workers came to the rescue, climbing onto the wreckage with ladders and forklifts[31] and pulling trapped people out of their cars from under a four-foot gap in some sections.

[69] Employees from Pacific Pipe drove heavy lift equipment to the scene and started using it to raise sections of fallen freeway enough to allow further rescue.

[74] Dubbed "Lucky Buck" by the local radio, Helm lived for another 29 days on life support, but then died of respiratory failure at the age of 58.

[80] San Francisco Municipal Railway (Muni) lost all power to electric transit systems when the quake hit, but otherwise suffered little damage and no injuries to operators or riders.

When the earthquake struck at approximately 5:04 PDT, sportscaster Tim McCarver was narrating taped highlights of Game 2, which had been played two days prior across the Bay Bridge in Oakland.

[95] The network put up a green ABC Sports "World Series" technical difficulties telop graphic while it scrambled to repair the video feed (the broadcast cameras and mics were powered by the local power supply), but audio from the stadium was restored after thirteen seconds via a telephone link: Al Michaels: Well, heh, I don't know if we're on the air... We are in commercial, I guess.

[98] KGO-TV, the local owned-and-operated ABC station in San Francisco, lost power for almost 15 minutes upon the start of the earthquake, before beginning its coverage with anchor Cheryl Jennings.

KTVU anchors Dennis Richmond and Elaine Corral began their coverage from the station's parking lot, as power had not yet been restored to that section of Oakland.

[101] Inside Candlestick Park, fewer than half of the more than 62,000 fans[22] had reached their seats by the time of the quake, and the load on the structure of the stadium was lower than maximum.

[102] There had also been a seismic-strengthening project previously completed on the upper deck concrete windscreen that may have prevented large numbers of injuries in the event of serious damage or even a catastrophic collapse.

Bryant Gumbel, Jane Pauley and Deborah Norville anchored from Chicago (where they had planned to originally do a special celebratory edition), with reports done by Bob Jamieson and Don Oliver in San Francisco, and George Lewis in Oakland.