At 5:04 p.m. on Tuesday, Oct. 17, 1989, a magnitude 6.9 earthquake shook the San Francisco and Monterey Bay regions. Thirty-seven years later, it is still the Bay Area's defining modern quake.
The quake
The California Geological Survey says the epicenter was on the San Andreas fault near Mount Loma Prieta in the Santa Cruz Mountains, about 10 miles northeast of Santa Cruz. The focal depth was 11 miles, which is deeper than typical California quakes. Shaking lasted about 20 seconds, and the quake was felt as far away as San Diego and western Nevada. A magnitude 5.2 aftershock hit about 2.5 minutes later.
The toll
According to the CGS, 63 people were killed, 3,757 were injured and 12,053 were displaced. Direct damage was estimated at $6.8 billion, and damage plus business interruption at as much as $10 billion. A total of 18,306 houses were damaged and 963 destroyed.
Where it hit hardest
The USGS says the most severe property damage was in Oakland and San Francisco, about 62 miles north of the fault segment that slipped. Los Gatos, Santa Cruz and Watsonville were heavily damaged near the epicenter. Spans collapsed on three bridges, including the San Francisco-Oakland Bay Bridge, where one person died. Liquefaction badly damaged buildings in San Francisco's Marina District. More than 1,000 landslides and rockfalls hit the Santa Cruz Mountains, and one on Highway 17 disrupted traffic for about a month.
The USGS says engineered buildings, including those near the epicenter, generally held up well. Most severe building damage was to unreinforced masonry buildings.
The lesson
The USGS calls Loma Prieta a wake-up call to prepare for potentially even more devastating quakes. The CGS notes that a magnitude 7.5 earthquake on the Hayward Fault could cause $65 billion in damage.