Photos related to the 1989 Loma Prieta earthquake.
M 6.9 October 17, 1989 Loma Prieta Earthquake
Completed
By Earthquake Hazards Program
October 8, 2024
The 1989 Loma Prieta earthquake ended decades of tranquility in the San Francisco Bay region. It was a wakeup call to prepare for the potentially even more devastating shocks that are inevitable in the future. Since 1989, the work of the U.S. Geological Survey and other organizations has improved understanding of the seismic threat in the Bay region, promoted awareness of earthquake hazards, and contributed to more effective strategies to reduce earthquake losses. These efforts will help reduce the impact of future large quakes in the San Francisco Bay region. -Robert Page, U.S. Geological Survey
Seismic Waves ShakeMovie
Seismic Waves ShakeMovie
ShakeMovie is a computer simulation of seismic shaking computed in the immediate aftermath of a significant earthquake in California. In this case, the ShakeMovie was generated for the 35th Anniversary of the 1989 Loma Prieta earthquake.
Ground Shaking Simulation
Ground Shaking Simulation
Ground shaking simulations provide a way to fill in the areas between the discrete observations using computer models. The simulations rely on mathematical representations of the earthquake rupture and wave propagation that are specifically designed for the Loma Prieta region, based in part on the observed ground shaking values.
ShakeMap
ShakeMap
ShakeMap is based on direct observations of ground shaking. These observations include both instrumental recordings and eyewitness intensity estimates, but only provide information at discrete locations.
Sources/Usage: Public Domain. View Media Details
Overview
On October 17, 1989, at 5:04 PM (PDT), a magnitude 6.9 earthquake severely shook the San Francisco and Monterey Bay regions. The epicenter was located near Loma Prieta peak in the Santa Cruz Mountains, approximately 9 miles northeast of Santa Cruz and 60 miles southeast of San Francisco. It was the strongest earthquake to hit the San Francisco Bay region since the M 7.9 Great San Francisco earthquake of 1906, causing 63 deaths, 3757 injuries, and an estimated $6 billion in property damage.
Infrastructure and Property Damage
The most severe property damage occurred in Oakland and San Francisco, about 62 miles north of the fault segment that slipped on the San Andreas. Los Gatos, Santa Cruz and Watsonville sustained heavy damage in the epicentral region. Other towns in the area that experienced severe property damage include Boulder Creek, Corralitos, Hollister, Moss Landing, and several smaller communities in the Santa Cruz Mountains.
Sources/Usage: Public Domain. View Media Details
Engineered buildings, including those near the epicenter, performed well during the earthquake. Most of the severe damage was sustained by unreinforced masonry (URM) buildings constructed of wood-frame roof and floor systems supported by unreinforced brick walls. Severe shaking damaged many buildings in the Santa Cruz Pacific Garden Mall, which consisted of several blocks of URM store buildings.
More than 80 of the 1500 bridges in the area sustained minor damage: 10 required temporary supports and 10 were closed due to major structural damage. One or more spans collapsed on three bridges, including the San Francisco - Oakland Bay Bridge (1 death). The most severe damage occurred to older structures on poor ground, such as the Cypress Street Viaduct (41 deaths). Damage to the transportation system was estimated at $1.8 billion.
Geology
Liquefaction caused severe damage to buildings in San Francisco's Marina district and contributed significantly to the property damage in the Santa Cruz and Monterey Bay areas. Structures damaged by liquefaction include buildings, bridges, highways, pipelines, port facilities, airport runways and levees.
Sources/Usage: Public Domain. View Media Details
Most of the more than 1000 landslides and rockfalls occurred in the epicentral zone in the Santa Cruz Mountains. One slide, on State Highway 17, disrupted traffic for about a month.
The only surface fracturing that might be attributed to primary tectonic faulting occurred along a trace of the San Andreas near Mount Madonna Road in the Corralitos area, where en echelon cracks showed about 3/4 inch of right-lateral displacement. Six feet of right-lateral strike-slip and 4 feet of reverse-slip was inferred from geodetic data. In Los Altos and Los Gatos, ground deformation appeared to be associated closely with zones of heavy structural damage and broken underground utility lines.
Learn More
Earthquake Details
Tectonic summary, maps and data.
Did You Feel It?
View the map of shaking intensity based on 11,000+ reports or tell us about your own experience (available in multiple languages).
Remembering Loma Prieta Earthquake 30 Years Later (video)
Looking back to see how far we've come. By: USGS scientists Tom Holzer, David Schwartz, Jessica Murray, and Annemarie Baltay.
USGS Professional Papers on Loma Prieta Summaries
Four Loma Prieta Earthquake Professional Papers, each containing multiple chapters, document the earthquake.
- Professional Paper 1550: Earthquake Occurrence
- Professional Paper 1551: Strong Ground Motion and Ground Failure
- Professional Paper 1552: Performance of the Built Environment
- Professional Paper 1553: Societal Response
California Geological Survey: 1989 Loma Prieta Earthquake
Background info and overview of the earthquake.
Berkeley Seismological Laboratory: 1989 Loma Prieta Earthquake
Maps, photos and details about the earthquake.
Faultline: Remembering Loma Prieta
A personal account of the events unfolding, by Mary K. Miller of the Exploratorium.
Additional Resources
- Loma Prieta earthquake media resources
- What if the ShakeAlert Earthquake Early Warning System Had Been Operating
- Earthquake outlook for the San Francisco Bay region 2014–2043
- Protecting Your Family From Earthquakes (English/Spanish; .pdf)
- Protecting Your Family From Earthquakes (Asian-languages; .pdf)
- Earthquake Strengthening of Cripple Walls in Wood-Frame Dwellings (.pdf)
- Earthquake Country Alliance Bay Area
Scientific Staff
Below are multimedia items associated with this project.
1989 Loma Prieta
Photos related to the 1989 Loma Prieta earthquake.
October 17, 1989 (Part 1)
On October 17, 1989, at 5:04 pm a magnitude M6.9 earthquake struck near Loma Prieta, California. It was a tragic reminder of the destructive power of earthquakes. However, it was also a watershed moment in seismic research. 30 years later, we revisit the earthquake through the eyes of the scientists who experienced it. And studied it. These are their stories.
On October 17, 1989, at 5:04 pm a magnitude M6.9 earthquake struck near Loma Prieta, California. It was a tragic reminder of the destructive power of earthquakes. However, it was also a watershed moment in seismic research. 30 years later, we revisit the earthquake through the eyes of the scientists who experienced it. And studied it. These are their stories.
October 17, 1989 (Part 2)
On October 17, 1989, at 5:04 pm a magnitude M6.9 earthquake struck near Loma Prieta, California. It was a tragic reminder of the destructive power of earthquakes. However, it was also a watershed moment in seismic research. 30 years later, we revisit the earthquake through the eyes of the scientists who experienced it. And studied it. These are their stories.
On October 17, 1989, at 5:04 pm a magnitude M6.9 earthquake struck near Loma Prieta, California. It was a tragic reminder of the destructive power of earthquakes. However, it was also a watershed moment in seismic research. 30 years later, we revisit the earthquake through the eyes of the scientists who experienced it. And studied it. These are their stories.
October 17, 1989 (Part 3)
On October 17, 1989, at 5:04 pm a magnitude M6.9 earthquake struck near Loma Prieta, California. It was a tragic reminder of the destructive power of earthquakes. However, it was also a watershed moment in seismic research. 30 years later, we revisit the earthquake through the eyes of the scientists who experienced it. And studied it.
On October 17, 1989, at 5:04 pm a magnitude M6.9 earthquake struck near Loma Prieta, California. It was a tragic reminder of the destructive power of earthquakes. However, it was also a watershed moment in seismic research. 30 years later, we revisit the earthquake through the eyes of the scientists who experienced it. And studied it.
October 17, 1989 (Part 4)
On October 17, 1989, at 5:04 pm a magnitude M6.9 earthquake struck near Loma Prieta, California. It was a tragic reminder of the destructive power of earthquakes. However, it was also a watershed moment in seismic research. 30 years later, we revisit the earthquake through the eyes of the scientists who experienced it. And studied it. These are their stories.
On October 17, 1989, at 5:04 pm a magnitude M6.9 earthquake struck near Loma Prieta, California. It was a tragic reminder of the destructive power of earthquakes. However, it was also a watershed moment in seismic research. 30 years later, we revisit the earthquake through the eyes of the scientists who experienced it. And studied it. These are their stories.
Prototype Earthquake Early Warning System (Interview)
Retired seismologist David Oppenheimer reflects on the first prototype earthquake early warning system used during the 1989 Loma Prieta earthquake. Scientists deployed an analog system to notify first responders of impending earthquake activity as they worked on rescue efforts at the Cypress Viaduct collapse in Oakland, CA.
Retired seismologist David Oppenheimer reflects on the first prototype earthquake early warning system used during the 1989 Loma Prieta earthquake. Scientists deployed an analog system to notify first responders of impending earthquake activity as they worked on rescue efforts at the Cypress Viaduct collapse in Oakland, CA.
Loma Prieta: 20 Years Later, Bay Area Safer
Host Leslie Gordon interviews three USGS earthquake scientists, David Oppenheimer, Carol Prentice, and Tom Holzer about the scientific advances made in the last 20 years since the Loma Prieta earthquake struck northern California.
Host Leslie Gordon interviews three USGS earthquake scientists, David Oppenheimer, Carol Prentice, and Tom Holzer about the scientific advances made in the last 20 years since the Loma Prieta earthquake struck northern California.
The 1989 Loma Prieta earthquake ended decades of tranquility in the San Francisco Bay region. It was a wakeup call to prepare for the potentially even more devastating shocks that are inevitable in the future. Since 1989, the work of the U.S. Geological Survey and other organizations has improved understanding of the seismic threat in the Bay region, promoted awareness of earthquake hazards, and contributed to more effective strategies to reduce earthquake losses. These efforts will help reduce the impact of future large quakes in the San Francisco Bay region. -Robert Page, U.S. Geological Survey
Seismic Waves ShakeMovie
Seismic Waves ShakeMovie
ShakeMovie is a computer simulation of seismic shaking computed in the immediate aftermath of a significant earthquake in California. In this case, the ShakeMovie was generated for the 35th Anniversary of the 1989 Loma Prieta earthquake.
Ground Shaking Simulation
Ground Shaking Simulation
Ground shaking simulations provide a way to fill in the areas between the discrete observations using computer models. The simulations rely on mathematical representations of the earthquake rupture and wave propagation that are specifically designed for the Loma Prieta region, based in part on the observed ground shaking values.
ShakeMap
ShakeMap
ShakeMap is based on direct observations of ground shaking. These observations include both instrumental recordings and eyewitness intensity estimates, but only provide information at discrete locations.
Sources/Usage: Public Domain. View Media Details
Overview
On October 17, 1989, at 5:04 PM (PDT), a magnitude 6.9 earthquake severely shook the San Francisco and Monterey Bay regions. The epicenter was located near Loma Prieta peak in the Santa Cruz Mountains, approximately 9 miles northeast of Santa Cruz and 60 miles southeast of San Francisco. It was the strongest earthquake to hit the San Francisco Bay region since the M 7.9 Great San Francisco earthquake of 1906, causing 63 deaths, 3757 injuries, and an estimated $6 billion in property damage.
Infrastructure and Property Damage
The most severe property damage occurred in Oakland and San Francisco, about 62 miles north of the fault segment that slipped on the San Andreas. Los Gatos, Santa Cruz and Watsonville sustained heavy damage in the epicentral region. Other towns in the area that experienced severe property damage include Boulder Creek, Corralitos, Hollister, Moss Landing, and several smaller communities in the Santa Cruz Mountains.
Sources/Usage: Public Domain. View Media Details
Engineered buildings, including those near the epicenter, performed well during the earthquake. Most of the severe damage was sustained by unreinforced masonry (URM) buildings constructed of wood-frame roof and floor systems supported by unreinforced brick walls. Severe shaking damaged many buildings in the Santa Cruz Pacific Garden Mall, which consisted of several blocks of URM store buildings.
More than 80 of the 1500 bridges in the area sustained minor damage: 10 required temporary supports and 10 were closed due to major structural damage. One or more spans collapsed on three bridges, including the San Francisco - Oakland Bay Bridge (1 death). The most severe damage occurred to older structures on poor ground, such as the Cypress Street Viaduct (41 deaths). Damage to the transportation system was estimated at $1.8 billion.
Geology
Liquefaction caused severe damage to buildings in San Francisco's Marina district and contributed significantly to the property damage in the Santa Cruz and Monterey Bay areas. Structures damaged by liquefaction include buildings, bridges, highways, pipelines, port facilities, airport runways and levees.
Sources/Usage: Public Domain. View Media Details
Most of the more than 1000 landslides and rockfalls occurred in the epicentral zone in the Santa Cruz Mountains. One slide, on State Highway 17, disrupted traffic for about a month.
The only surface fracturing that might be attributed to primary tectonic faulting occurred along a trace of the San Andreas near Mount Madonna Road in the Corralitos area, where en echelon cracks showed about 3/4 inch of right-lateral displacement. Six feet of right-lateral strike-slip and 4 feet of reverse-slip was inferred from geodetic data. In Los Altos and Los Gatos, ground deformation appeared to be associated closely with zones of heavy structural damage and broken underground utility lines.
Learn More
Earthquake Details
Tectonic summary, maps and data.
Did You Feel It?
View the map of shaking intensity based on 11,000+ reports or tell us about your own experience (available in multiple languages).
Remembering Loma Prieta Earthquake 30 Years Later (video)
Looking back to see how far we've come. By: USGS scientists Tom Holzer, David Schwartz, Jessica Murray, and Annemarie Baltay.
USGS Professional Papers on Loma Prieta Summaries
Four Loma Prieta Earthquake Professional Papers, each containing multiple chapters, document the earthquake.
- Professional Paper 1550: Earthquake Occurrence
- Professional Paper 1551: Strong Ground Motion and Ground Failure
- Professional Paper 1552: Performance of the Built Environment
- Professional Paper 1553: Societal Response
California Geological Survey: 1989 Loma Prieta Earthquake
Background info and overview of the earthquake.
Berkeley Seismological Laboratory: 1989 Loma Prieta Earthquake
Maps, photos and details about the earthquake.
Faultline: Remembering Loma Prieta
A personal account of the events unfolding, by Mary K. Miller of the Exploratorium.
Additional Resources
- Loma Prieta earthquake media resources
- What if the ShakeAlert Earthquake Early Warning System Had Been Operating
- Earthquake outlook for the San Francisco Bay region 2014–2043
- Protecting Your Family From Earthquakes (English/Spanish; .pdf)
- Protecting Your Family From Earthquakes (Asian-languages; .pdf)
- Earthquake Strengthening of Cripple Walls in Wood-Frame Dwellings (.pdf)
- Earthquake Country Alliance Bay Area
Scientific Staff
Below are multimedia items associated with this project.
1989 Loma Prieta
Photos related to the 1989 Loma Prieta earthquake.
Photos related to the 1989 Loma Prieta earthquake.
October 17, 1989 (Part 1)
On October 17, 1989, at 5:04 pm a magnitude M6.9 earthquake struck near Loma Prieta, California. It was a tragic reminder of the destructive power of earthquakes. However, it was also a watershed moment in seismic research. 30 years later, we revisit the earthquake through the eyes of the scientists who experienced it. And studied it. These are their stories.
On October 17, 1989, at 5:04 pm a magnitude M6.9 earthquake struck near Loma Prieta, California. It was a tragic reminder of the destructive power of earthquakes. However, it was also a watershed moment in seismic research. 30 years later, we revisit the earthquake through the eyes of the scientists who experienced it. And studied it. These are their stories.
October 17, 1989 (Part 2)
On October 17, 1989, at 5:04 pm a magnitude M6.9 earthquake struck near Loma Prieta, California. It was a tragic reminder of the destructive power of earthquakes. However, it was also a watershed moment in seismic research. 30 years later, we revisit the earthquake through the eyes of the scientists who experienced it. And studied it. These are their stories.
On October 17, 1989, at 5:04 pm a magnitude M6.9 earthquake struck near Loma Prieta, California. It was a tragic reminder of the destructive power of earthquakes. However, it was also a watershed moment in seismic research. 30 years later, we revisit the earthquake through the eyes of the scientists who experienced it. And studied it. These are their stories.
October 17, 1989 (Part 3)
On October 17, 1989, at 5:04 pm a magnitude M6.9 earthquake struck near Loma Prieta, California. It was a tragic reminder of the destructive power of earthquakes. However, it was also a watershed moment in seismic research. 30 years later, we revisit the earthquake through the eyes of the scientists who experienced it. And studied it.
On October 17, 1989, at 5:04 pm a magnitude M6.9 earthquake struck near Loma Prieta, California. It was a tragic reminder of the destructive power of earthquakes. However, it was also a watershed moment in seismic research. 30 years later, we revisit the earthquake through the eyes of the scientists who experienced it. And studied it.
October 17, 1989 (Part 4)
On October 17, 1989, at 5:04 pm a magnitude M6.9 earthquake struck near Loma Prieta, California. It was a tragic reminder of the destructive power of earthquakes. However, it was also a watershed moment in seismic research. 30 years later, we revisit the earthquake through the eyes of the scientists who experienced it. And studied it. These are their stories.
On October 17, 1989, at 5:04 pm a magnitude M6.9 earthquake struck near Loma Prieta, California. It was a tragic reminder of the destructive power of earthquakes. However, it was also a watershed moment in seismic research. 30 years later, we revisit the earthquake through the eyes of the scientists who experienced it. And studied it. These are their stories.
Prototype Earthquake Early Warning System (Interview)
Retired seismologist David Oppenheimer reflects on the first prototype earthquake early warning system used during the 1989 Loma Prieta earthquake. Scientists deployed an analog system to notify first responders of impending earthquake activity as they worked on rescue efforts at the Cypress Viaduct collapse in Oakland, CA.
Retired seismologist David Oppenheimer reflects on the first prototype earthquake early warning system used during the 1989 Loma Prieta earthquake. Scientists deployed an analog system to notify first responders of impending earthquake activity as they worked on rescue efforts at the Cypress Viaduct collapse in Oakland, CA.
Loma Prieta: 20 Years Later, Bay Area Safer
Host Leslie Gordon interviews three USGS earthquake scientists, David Oppenheimer, Carol Prentice, and Tom Holzer about the scientific advances made in the last 20 years since the Loma Prieta earthquake struck northern California.
Host Leslie Gordon interviews three USGS earthquake scientists, David Oppenheimer, Carol Prentice, and Tom Holzer about the scientific advances made in the last 20 years since the Loma Prieta earthquake struck northern California.