1989 Loma Prieta earthquake
|Date||October 17, 1989|
|Origin time||5:04:15 PDT |
|Duration||8 – 15 seconds |
|Magnitude||6.9 Mw |
|Depth||19 km (12 mi) |
Central Coast (California)
San Francisco Bay Area
|Total damage||$5.6 – 6 billion |
|Max. intensity||IX (Violent) |
|Peak acceleration||.65g (at epicenter) |
|Landslides||1,000 – 4,000 |
5.3 ML June 27, 1988 
5.4 ML August 8, 1989 
|Casualties||63 killed, 3,757 injured |
The 1989 Loma Prieta earthquake occurred in northern California on October 17 at 5:04 p.m. local time. The shock was centered in a sparsely populated area approximately 10 mi (16 km) northeast of Santa Cruz on a section of the San Andreas Fault System and was named for the nearby Loma Prieta peak in the Santa Cruz Mountains. With a maximum Modified Mercalli intensity of IX (Violent), and a moment magnitude of 6.9, the shock was responsible for 63 deaths and 3,757 injuries in the affected areas. Damage was heavy in Santa Cruz County and less so to the south in Monterey County, but effects extended well to the north (and farther from the epicenter) into the San Francisco Bay Area, both on the San Francisco Peninsula and across the bay in Oakland.
The Loma Prieta (or southern Santa Cruz Mountains) segment of the San Andreas Fault System had been undergoing a long period of quiescence until several moderate foreshocks occurred in June 1988 and again in August 1989. The foreshocks were of significance because that segment of the San Andreas Fault System had been so quiet that it had been labeled a seismic gap. No large earthquake had occurred in that region since the 1906 San Francisco earthquake. No surface faulting occurred, though a large number of other ground failures and landslides occurred, especially in the Summit area of the Santa Cruz Mountains. Liquefaction was also a significant issue, especially in the heavily damaged Marina District of San Francisco, but its effects were also seen in the East Bay, and near the shore of Monterey Bay, where a non-destructive tsunami was also observed. Abundant strong motion records were captured due to a large number of seismometers that were operating in the region.
Due to the sports coverage of the 1989 World Series, it became the first major earthquake in the United States that was broadcast live on national television. Rush-hour traffic on the Bay Area freeways was lighter than normal due to nearly 62,000 people present at the game at Candlestick Park in San Francisco, and this may have prevented a larger loss of life, as several of the Bay Area's major transportation structures suffered catastrophic failures. The collapse of a section of the double-deck Nimitz Freeway in Oakland was the site of the single largest number of casualties for the event, but the collapse of man-made structures and other related accidents contributed to casualties occurring in San Francisco, Los Altos, and Santa Cruz.
- Forecasts 1.1
- Foreshocks 1.2
- Injuries and fatalities 2.1
- Magnetic disturbances 2.2
- Marina District 3.1
- Santa Cruz and Monterey counties 3.2
- San Francisco – Oakland Bay Bridge 3.3
- Oakland and Interstate 880/Cypress Viaduct 3.4
- Effects on transportation 3.5
- 1989 World Series 4
- In popular culture 5
- See also 6
- References 7
- External links 8
The history of earthquake investigations in California has been largely focused on the San Andreas Fault System, due to its strong influence in the state as the boundary between the Pacific Plate and the North American Plate; it is the most studied fault on earth. Andrew Lawson, a geologist from the University of California, Berkeley, had named the fault after the San Andreas Lake (prior to the occurrence of the 1906 San Francisco earthquake) and later led an investigation into that event. For more than fifty years before the theory of plate tectonics established its motion as strike-slip, Lawson became embroiled in a controversy due to his contention that the fault was primarily of the dip-slip type.
At the time of the 1906 San Francisco earthquake, the San Andreas Fault ruptured for a length of 290 mi (470 km), both to the north of San Francisco and to the south in the Santa Cruz Mountains region. 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 1989 Loma Prieta event originated on an undiscovered oblique slip reverse fault that is located adjacent to the San Andreas Fault.
Since many forecasts had been presented for the region near Loma Prieta, seismologists were not taken by surprise by the October 1989 event. Between 1910 and 1989 there were 20 widely-varying forecasts that were introduced, with some that were highly specific, covering multiple aspects of an event, while others were less complete and vague. With a M6.5 event on the San Juan Bautista segment, or an M7 event on the San Francisco Peninsula segment, United States Geological Survey (USGS) seismologist Allan Lindh's 1983 forecasted rupture length of 25 miles (40 km) (starting near Pajaro Gap, and continuing to the northwest) for the San Juan Bautista segment nearly matched the actual rupture length of the 1989 event. An updated forecast was presented in 1988, at which time Lindh took the opportunity to assign a new name to the San Juan Bautista segment – the Loma Prieta segment.
In early 1988, the Working Group for California Earthquake Probabilities (WGCEP) convened and made several statements regarding their forecasts for the Hayward Fault, the 360 mi (580 km) northern San Andreas Fault segment, the 56 mi (90 km) San Francisco Peninsula segment, and a 19–22 mi (31–35 km) portion of that segment which was referred to as the southern Santa Cruz Mountains segment. The thirty year probability for one or more M7 earthquakes in the study area was given as 50%, but because of a lack of information and low confidence, a 30% probability was assigned to the Southern Santa Cruz Mountains segment. Two moderate shocks, referred to as the Lake Elsman earthquakes by the USGS, occurred in the Santa Cruz Mountains region in June 1988 and again in August 1989. Following each event, the State office of Emergency Services issued (for the first time in Bay Area history) short term advisories for a possible large earthquake, which meant there was "a slightly increased likelihood of an M6.5 event on the Santa Cruz Mountains segment of the San Andreas fault". 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.
The M5.3 June 1988 and the M5.4 August 1989 events (local magnitude) also occurred on previously unknown oblique reverse faults and were within 3 mi (4.8 km) 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 4 in (100 mm) of strike-slip and substantially less reverse-slip) and although they occurred on separate faults and well before the mainshock, Perfettini et al. considered these to be foreshocks due to their location in space and time relative to the main event. Each event's aftershock sequence and impact on stress drop was closely examined, and the results of their study indicated that the shocks did have an impact on the mainshock's rupture process. Following the August 8, 1989 shock, in anticipation of an upcoming large earthquake, staff at the University of California, Santa Cruz deployed four accelerometers in the area, which were positioned at the UCSC campus, two residences in Santa Cruz, and a home in Los Gatos. 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.
The June 27, 1988 shock occurred with a maximum intensity of VI (Strong). Its effects included broken windows in Los Gatos, and other light damage in Holy City, where increased flow was observed at a water well. Farther away from the Santa Cruz Mountains, pieces of concrete fell from a parking structure at the Sunnyvale Town Center, a two-level shopping mall in Santa Clara County. 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. Other damage included cracked walls and foundations and broken underground pipes. At the office of the Los Gatos City Manager, a window that was cracked had also been broken in the earlier shock. Also in Los Gatos, one man died when he exited a building through a window and fell five stories. The event was followed hours later by a M4.5 aftershock that had a maximum intensity of V (Moderate).
The epicenter of the earthquake was in the Forest of Nisene Marks State Park in the Santa Cruz Mountains, approximately 2–3 miles (3–5 km) north of unincorporated Aptos and approximately 10 miles (16 km) northeast of Santa Cruz. Slip occurred along approximately 22 miles (35 km) of the fault at a depth of about 4.3–12.4 miles (7–20 km). The quake was named for the nearby Loma Prieta Peak which lies 5 mi (8 km) to the northeast in Santa Clara County.
Injuries and fatalities
Fifty-seven of the deaths were directly caused by the earthquake; six further fatalities were ruled to have been caused indirectly. In addition, there were 3,757 injuries as a result of the earthquake, 400 of which were serious. The highest number of fatalities, 42, occurred in Oakland because of the Cypress Street Viaduct collapse on the Nimitz Freeway (Interstate 880), where the upper level of a double-deck portion of the freeway collapsed, crushing the cars on the lower deck. One 50-foot (15 m) section of the San Francisco – Oakland Bay Bridge also collapsed, leading to a single fatality, a 23-year-old woman named Anamafi Moala. Three people were killed in the collapse of buildings along the Pacific Garden Mall in Santa Cruz, and five people were killed in the collapse of a brick wall on Bluxome Street in San Francisco.
When the earthquake hit, the third game of the 1989 World Series baseball championship was just beginning. Because of the unusual circumstance that both of the World Series teams (the San Francisco Giants and Oakland Athletics) were based in the affected area, many people had left work early or were staying late to participate in after work group viewings and parties. As a consequence 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, about 4.5 miles (7 km) from the epicenter. From October 5, they reported a substantial increase in noise was measured in the frequency range 0.01–10 Hz. The measurement instrument was a single-axis search-coil magnetometer that was being used for low frequency research. Precursor increases of noise apparently started a few days before the earthquake, with noise in the range .01–.5 Hz rising to exceptionally high levels about three hours before the earthquake. Though this pattern gave scientists new ideas for research into potential precursors to earthquakes, and the Fraser-Smith et al. report remains one of the most frequently cited examples of a specific earthquake precursor, more recent studies have cast doubt on the connection, attributing the Corralitos signals to either unrelated magnetic disturbance or, even more simply, to sensor-system malfunction.
The earthquake caused severe damage in some very specific locations in the San Francisco Bay Area, most notably on unstable soil in San Francisco and Oakland. Oakland City Hall was evacuated after the earthquake until US$80M seismic retrofit and hazard abatement work was completed in 1995. Many other communities sustained severe damage throughout the region located in Alameda, San Mateo, Santa Clara, San Benito, Santa Cruz and Monterey counties. 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. Other effects included sand volcanoes, landslides and ground ruptures. Some 12,000 homes and 2,600 businesses were damaged.
In Santa Cruz, close to the epicenter, 40 buildings collapsed, killing six people. At the Santa Cruz Beach Boardwalk, the Plunge building was significantly damaged. Liquefaction also caused damage in the Watsonville area. For example, sand volcanoes formed in a field near Pajaro as well as in a strawberry field. The Ford's department store in Watsonville experienced significant damage, including a crack down the front of the building. Many homes were dislodged if they were not bolted to their foundations. There were structural failures of twin bridges across Struve Slough near Watsonville. In Moss Landing, the liquefaction destroyed the causeway that carried the Moss Beach access road across tidewater basin, damaged the approach and abutment of the bridge linking Moss Landing spit to the mainland and cracked the paved road on Paul's Island. In the Old Town historical district of the city of Salinas, unreinforced masonry buildings were partially destroyed.
An estimated 1.4 million people lost power following the quake, mainly due to damaged electrical substations. Many San Francisco radio and television stations were temporarily knocked off the air. KRON-TV was off the air for about half an hour, while KGO-AM was off the air for about 40 minutes. About an hour and 40 minutes after the quake, KTVU resumed broadcasting, with their news anchors reporting from the station's parking lot. KCBS-AM switched immediately to backup power and managed to stay on air despite a subsequent generator failure. KCBS later won a Peabody Award for their news coverage, as did KGO-TV. Power was restored to most of San Francisco by midnight, and all but 12,000 customers had their power restored within two days.
The quake caused an estimated $6 billion in property damage, becoming one of the most expensive natural disasters in U.S. history at the time. It was the largest earthquake to occur on the San Andreas Fault since the great
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The deadliest earthquake in the United States in more than 80 years kills close to 300 people...
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- After the Shock (TV 1990) at the Internet Movie Database
- Miracle on Interstate 880 (TV 1993) at the Internet Movie Database
- Journeyman (TV Series 2007) at the Internet Movie Database
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- Todd Kennedy Hitting the American Highway: The Ontology of the Hobo-hero - 2007 "...she also utilizes Dylan's rain imagery as blinding when she says, "Oh the weather and a blinding hail / We were riding high 'til the '89 quake / Hit the Santa Cruz garden mall / Like a Wrecking Ball... p.180"
- Top 10 Craziest Events Caught on Live TV
- Top 10 Craziest Events Caught on Live TV
- Top 10 Crazy Moments in Sports
- Top 10 Crazy Moments in Sports
- 1994 Northridge earthquake
- Earthquake engineering
- List of earthquakes in California
- List of earthquakes in the United States
- The events in the Full House episode, "Aftershocks" (December 8, 1989), took place following the Loma Prieta earthquake; it centered on Stephanie Tanner having a hard time telling her father Danny about how she fears another aftershock might happen and kill him, since he is a widowed single father, as well as other members of the family.
- After The Shock (1990), a made-for-TV movie with stories of rescue after the disaster.
- Miracle on Interstate 880 (1993), a TV movie fictionalization and re-enactment of events at the collapsed Cypress Structure.
- Journeyman (2007), TV show on NBC in which the main character travels back in time to save a person who died during the earthquake. Occurs in third episode, "Game Three," in reference to the 1989 World Series.
- Midnight Caller (1990), TV show set in San Francisco in the aftermath of the earthquake. In the show, a caller jokes about Candlestick Park being renamed "Wiggly Field".
- Medium (2005), TV show on NBC in which a character uses her coincidental presence in Oakland during the earthquake as an opportunity to fake her own death and disappear. Occurs in the episode "Sweet Dreams".
- Fringe (2008), TV show on FOX in which a character's parents were killed in the Oakland Bay Bridge collapse, while the Observer was watching her and her parents. Occurs in the episode "August". In a later episode ("Amber 31422", November 4, 2010), the alternate Walter Bishop refers to October 17, 1989, as the first time he used his amber-based protocol to heal breaches between the two universes.
- The Grateful Dead performed the Rodney Crowell song "California Earthquake" at their concert in Philadelphia, Pennsylvania, on October 20, 1989, then again three nights later in Charlotte, North Carolina—the only times the band ever performed the song. On December 6, 1989, the band played an earthquake benefit concert at the Oakland-Alameda County Coliseum Arena.
- Gillian Welch in the song "Wrecking Ball" on her Soul Journey album.
- Grand Theft Auto: San Andreas (2004 video game by Rockstar Games) takes place in 1992, and the fictional city of San Fierro (based on San Francisco) has a few areas that have been destroyed by the earthquake that took place 3 years before the game took place.
- WatchMojo.com ranked this incident at #9 on Top 10 Craziest Events Caught on Live TV, and #10 on Top 10 Crazy Moments in Sports.
In popular culture
Inside Candlestick Park, fewer than half of the more than 62,000 fans had reached their seats by the time of the quake, and the load on the structure of the stadium was lower than maximum. There had also been a seismic-strengthening project previously completed on the upper deck concrete windscreen. Fans reported that the stadium moved in an articulated manner as the earthquake wave passed through it, that the light standards swayed by many feet, and that the concrete upper deck windscreen moved in a wave-like manner over a distance of several feet. Electrical power to the stadium was lost, forcing the game to be postponed. The series did not resume for 10 days. After the shaking subsided, many of the players on both teams immediately searched for and gathered family and friends from the stands before evacuating the facility.
The network put up a green ABC Sports graphic as the audio was switched to a telephone link. Michaels cracked, "Well, folks, that's the greatest open in the history of television, bar none!" accompanied by the excited screams of fans who had no idea of the devastation elsewhere. ABC then switched to an episode of Roseanne which was on standby for a rain delay situation, while attempting to restore electricity to its remote equipment. With anchorman Ted Koppel in position in Washington, D.C., ABC News began continuous coverage of the quake about 5:40 p.m. (Al Michaels, in the process, became a de facto on-site reporter for ABC), at the same time as CBS News. NBC News also began continuous coverage, with Tom Brokaw, about an hour later. ABC was able to use the Goodyear blimp to capture some images of the damage to the Bay Bridge.
Because it occurred minutes before the scheduled start of Game 3 of the 1989 World Series, the first moments of the earthquake were seen around the world as it happened. The World Series was being televised that year by U.S. network ABC. At the moment the quake struck, sportscaster Tim McCarver was narrating taped highlights of the previous Series game. Viewers saw the video signal begin to break up, heard McCarver repeat a sentence as the shaking distracted him, and heard McCarver's colleague Al Michaels exclaim, "I'll tell you what—we're having an earth—." At that moment, the feed from Candlestick Park was lost.
1989 World Series
- State Route 1: In Watsonville, the Struve Slough Bridge collapsed, with concrete/steel support columns punching through the bridge deck like toothpicks. The highway was closed for several months until it could be demolished and rebuilt. Another section of Highway 1 through Monterey suffered damage and had to be rebuilt as well. Additionally, the bridge carrying Highway 1 over the Salinas River near Fort Ord was damaged and subsequently rebuilt.
- Bay Area Rapid Transit: The BART rail system, which hauled commuters between the East Bay and San Francisco via the Transbay Tube, was virtually undamaged and only closed for post-earthquake inspection. With the Bay Bridge closed because of its damage, the Transbay Tube became the quickest way into San Francisco via Oakland for a month, and ridership increased in the three work weeks following the earthquake, going from 218,000 riders per average weekday to more than 330,000 post-quake, a 50 percent increase. BART instituted round-the-clock train service until December 3 when they returned to their normal schedule.
- Amtrak: Historic 16th Street Station in downtown Oakland suffered significant damage and was rendered structurally unsound. Amtrak would shift its Oakland operations to new station in Emeryville.
- Transbay Ferries: Ferry service between San Francisco and Oakland, which had ended decades before, was revived during the month-long closure of the Bay Bridge as an alternative to the overcrowded BART. A ferry terminal was put together in Alameda, and the U.S. Army Corps of Engineers dredged a suitable ferry dock at the Berkeley Marina. Additionally, the demolition of the quake-damaged Embarcadero Freeway led to the Ferry Building Terminal renovation, increasing the efficiency of ferry service to the peninsula. The passenger-only service proved popular and continues to expand its service.
- San Francisco – Oakland Bay Bridge, Interstate 80: The Bay Bridge was repaired and reopened to traffic in a month. However, the earthquake made it clear that the Bay Bridge, like many of California's toll bridges, required major repair or replacement for long-term viability and safety. Construction on a replacement for the eastern span began on January 29, 2002. The project was completed on September 2, 2013.
- Cypress Street Viaduct/Nimitz Freeway, Interstate 880: The double-decked Cypress Street Viaduct, Interstate 880 was demolished soon after the earthquake, and was not rebuilt until July 1997. The rebuilt highway was a single-deck rather than double-deck structure, and was re-routed around the outskirts of West Oakland, rather than bisecting it, as the Cypress Street Viaduct had done. The former route of the Cypress Street Viaduct was reopened as the ground-level Mandela Parkway.
- Embarcadero Freeway, State Route 480: Earthquake damage forced the closure and demolition of San Francisco's incomplete and controversial Embarcadero Freeway (State Route 480). This removal opened up San Francisco's Embarcadero area to new development. The elevated structure, which ran along San Francisco's waterfront, was later demolished and replaced with a ground-level boulevard.
- Southern Freeway, Interstate 280: Seismic damage also forced the long-term closure of Interstate 280 in San Francisco (north of US 101), another concrete freeway which had never been completed to its originally planned route. The uncompleted northernmost stub of I-280 was demolished during August–October 1995 while one connecting ramp between northbound I-280 and southbound US 101 was opened in December 1995. The full I-280 project was completed in late 1997.
- Central Freeway, U.S. Highway 101: San Francisco's Central Freeway (part of US 101 and a key link to the Bay Bridge flyover) was another concrete double-deck structure which faced demolition because of safety concerns. Originally terminating at Franklin Street and Golden Gate Avenue near San Francisco's Civic Center, the section past Fell Street was demolished first, then later the section between Mission and Fell Streets. The section from Mission Street to Market Street was rebuilt (completed September 2005) as a single-deck elevated freeway, touching down at Market Street and feeding into Octavia Boulevard, a ground-level urban parkway carrying traffic to and from the major San Francisco traffic arterials that the old elevated freeway used to connect to directly, including Fell and Oak Streets (which serve the city's western neighborhoods) and Franklin and Gough Streets (which serve northern neighborhoods and the Golden Gate Bridge).
- State Route 17: The mountain highway was closed for about one month because of a landslide. The route crosses the San Andreas Fault in the Santa Cruz Mountains, near the earthquake's epicenter.
The earthquake changed the Bay Area's automobile transportation landscape. Not only did the quake force seismic retrofitting of all San Francisco Bay Area bridges, it caused enough damage that some parts of the region's freeway system had to be demolished. Damage to the region's transportation system was estimated at $1.8 billion.
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. Cable cars and electric trains and buses were stalled in place—half of Muni's transport capability was lost for 12 hours. Muni relied on diesel buses to continue abbreviated service until electric power was restored later that night, and electric units could be inspected and readied for service on the morning of October 18. After 78 hours, 96 percent of Muni services were back in operation, including the cable cars. Amtrak intercity rail service into Oakland from Amtrak's California Zephyr continued, but the Coast Starlight was temporarily suspended north of Salinas because of damage to the Southern Pacific's Coast Line.
Immediately following the earthquake, San Francisco Bay Area airports closed to conduct visual inspection and damage assessment procedures. San Jose International Airport, Oakland International Airport and San Francisco International Airport all opened the next morning. Large cracks in Oakland's runway and taxiway reduced the usable length to two-thirds normal, and damage to the dike required quick remediation to avoid flooding the runway with water from the bay. Oakland Airport repair costs were assessed at $30 million.
|4.3 ML||Oct 18 at 00:38||1989|
|5.2 ML||Oct 18 at 00:41||1989|
|4.0 ML||Oct 18 at 02:26||1989|
|4.1 ML||Oct 18 at 03:30||1989|
|4.2 ML||Oct 18 at 04:50||1989|
|4.2 ML||Oct 18 at 05:18||1989|
|4.3 ML||Oct 18 at 10:22||1989|
|4.3 ML||Oct 19 at 9:53||1989|
|4.2 ML||Oct 21 at 10:22||1989|
|4.7 ML||Oct 21 at 22:14||1989|
|4.3 ML||Nov 2 at 05:50||1989|
|4.3 ML||Apr 18 at 13:37||1990|
|4.5 ML||Apr 18 at 13:41||1990|
|5.4 ML||Apr 18 at 13:53||1990|
|4.2 ML||Apr 18 at 14:52||1990|
|4.2 ML||Apr 18 at 15:28||1990|
|4.5 ML||Mar 24 at 03:42||1991|
|Dietz & Ellsworth 1997, p. 43|
Effects on transportation
Rebuilding the freeway took 11 years. In the meantime, traffic was detoured through nearby Interstate 980, causing increased congestion. Instead of rebuilding Interstate 880 over the same ground, Caltrans rerouted the freeway farther west around the outskirts of West Oakland to provide better access to the Port of Oakland and the San Francisco – Oakland Bay Bridge, and to meet community desires to keep the freeway from cutting through residential areas. Street-level Mandela Parkway now occupies the previous roadbed of the Cypress Structure.
, but then died of respiratory failure at the age of 57.life support Dubbed "Lucky Buck" by the local radio, Helm lived for another 29 days on  The stubborn efforts of the rescue workers were rewarded just after dawn on October 21 when survivor Buck Helm was freed from the wreckage, having spent 90 hours trapped in his crushed car under the rubble. Employees from Pacific Pipe (a now-closed factory adjoining the freeway) drove heavy lift equipment to the scene and started using it to raise sections of fallen freeway enough to allow further rescue. Hard-hatted factory workers continued their volunteer operation without stopping night and day until October 21, 1989, when they were forced to pause as U.S. President George H. W. Bush and California Governor  and pulling trapped people out of their mangled cars from under a four-foot gap in some sections. Sixty members of Oakland's Public Works Agency left the nearby city yard and joined rescue efforts. During the earthquake, the freeway buckled and twisted to its limits before the support columns failed and sent the upper deck crashing to the lower deck. In an instant, 41 people were crushed to death in their cars. Cars on the upper deck were tossed around violently, some of them flipped sideways and some of them were left dangling at the edge of the highway. Nearby residents and factory workers came to the rescue, climbing onto the wreckage with ladders and forklifts
Built in the late 1950s, the Cypress Street Viaduct, a stretch of Interstate 880, was a double-deck freeway section made of nonductile reinforced concrete that was constructed above and astride Cypress Street in Oakland. Roughly half of the land the Cypress Viaduct was built on was filled marshland, and half was somewhat more stable alluvium. Because of new highway structure design guidelines—the requirement of ductile construction elements—instituted following the 1971 San Fernando earthquake, a limited degree of earthquake reinforcement was retrofitted to the Cypress Viaduct in 1977. 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. When the earthquake hit, the shaking was amplified on the former marshland, and soil liquefaction occurred.
The worst disaster of the earthquake was the collapse of the two-level Cypress Street Viaduct of Interstate 880 in West Oakland. The failure of a 1.25-mile (2.0 km) section of the viaduct, also known as the "Cypress Structure" and the "Cypress Freeway", killed 42 and injured many more.
Oakland and Interstate 880/Cypress Viaduct
The San Francisco–Oakland Bay Bridge suffered severe damage, as a 76-by-50-foot (23 m × 15 m) section of the upper deck on the eastern cantilever side fell onto the deck below. The quake caused the Oakland side of the bridge to shift 7 in (18 cm) to the east, and caused the bolts of one section to shear off, sending the 250-short-ton (230 t) section of roadbed crashing down like a trapdoor. When that part of the bridge collapsed, one car drove into the hole, resulting in the death of the driver. Traffic on both decks came to a halt, blocked by the section of roadbed. Police began unsnarling the traffic jam, telling drivers to turn their cars around and drive back the way they had come. Eastbound drivers stuck on the lower deck between the collapse and Yerba Buena Island were routed up to the upper deck and westward back to San Francisco. 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. One of these drivers did not see the open gap in time; the car plunged over the edge and smashed onto the collapsed roadbed. The driver Anamafi Moala died, and the passenger was seriously injured. Caltrans removed and replaced the collapsed section, and re-opened the bridge on November 18.
San Francisco – Oakland Bay Bridge
The quake claimed one life in Watsonville; a driver who collided with panicked horses after they escaped their collapsed corral. 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. Many residents slept outside their homes out of concern for further damage from aftershocks, of which there were 51 with magnitudes greater than 3.0 in the following 24 hours, and 16 more the second day. The earthquake damaged several historic buildings in the Old Town district of Salinas, and some were later demolished.
During the first few days following the quake, electric power to most Santa Cruz county subscribers was out, and some areas had no water. Limited phone service remained online, providing a crucial link to rescue workers. Widespread search operations were organized to find possible victims inside the remains of fallen structures. As many as six teams of dogs and their handlers were at work identifying the large number of damaged buildings that held no victims.
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. Two police officers crawled through voids in the debris, found one victim alive and another dead inside the coffee house. Santa Cruz beach lifeguards assisted in moving the victims. Police dogs were brought in to help locate other victims. A woman was found dead inside Ford's. 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. Police arrested those who refused to stop searching. This became a political issue in the following days. The body of a young woman coffee worker was found under a collapsed wall late the next day.
In Santa Cruz, the Pacific Garden Mall was severely damaged, with falling debris killing three people, half of the six earthquake deaths in the Santa Cruz and Monterey Counties. Some 31 buildings were damaged enough to warrant demolition, seven of which had been listed in the Santa Cruz Historic Building Survey. The four oldest were built in 1894, the five oldest withstood the 1906 San Francisco earthquake.
Santa Cruz and Monterey counties
At the intersection of Beach and Divisadero Streets in San Francisco, a natural gas main rupture caused a major structure fire. The fire department selected bystanders to help run fire hoses from a distance because the nearby hydrant system failed. Since the bay was only two blocks from the burning buildings, water from the bay was pumped by the fireboat Phoenix, to engines on the shore, and from there sprayed on the fire. The apartment structures that collapsed were older buildings that included ground floor garages, which engineers refer to as a soft story building.
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. Some of the fill was rubble dumped into San Francisco Bay after the 1906 San Francisco earthquake, but most was sand and debris laid down in preparation for the 1915 Panama-Pacific International Exposition, a celebration of San Francisco's ability to rebound after its terrible catastrophe in 1906. After the Exposition, apartment buildings were erected on the landfill. In the 1989 earthquake, the water-saturated unconsolidated mud, sand and rubble suffered liquefaction, and the earthquake's vertical shock waves rippled the ground more severely.
Four people died in San Francisco's Marina District, four buildings were destroyed by fire, and seven buildings collapsed. Another 63 damaged structures were judged too dangerous to live in. Among the four deaths, one family lost their infant son who choked on dust while trapped for an hour inside their collapsed apartment.