Date: October 17, 1989, 5:04 p.m.
Magnitude: 6.9
Dead: 63
Injured: Nearly 3,800
Damage: More than 28,000 homes and businesses

More than 62,000 baseball fans were crowded into San Francisco's Candlestick Park, waiting for game three of baseball's 1989 World Series to begin when the ground began to shake.

A segment of the infamous San Andreas Fault had ruptured under the Loma Prieta peak in the Santa Cruz Mountains. The explosive release of energy lifted the mountains themselves and sent shock waves shooting through the Earth.

The city of Santa Cruz, 10 miles (16 kilometers) from the epicenter, was ripped apart first. The town of Watsonville, a center for frozen-vegetable processing, was devastated. Then the shock waves flew up the peninsula toward heavily populated San Francisco.

There the quake peeled a section of the San Francisco Bay Bridge open and collapsed the upper deck of a section of Oakland's Interstate 880. More than 40 slabs of concrete, each weighing 600 tons, slammed onto cars below.

The worst damage was in San Francisco's Marina district. Mud and sand, originally pumped in to fill shallow waters, had not been properly compacted. The quake's shock waves roiled the unstable soil into slush, a process called liquefaction. Amplification exaggerated the waves at the surface, increasing the ground shaking. Homes and businesses toppled into the slush, which acted like quicksand.

When the seconds-long earthquake was over, 63 people were dead or dying and nearly 3,800 people were injured. More than 28,000 structures were damaged—but not Candlestick Park. The World Series fans were rattled but unharmed.

Although California escaped with relatively few fatalities, experts stress that the Loma Prieta quake—despite its magnitude—was just a dress rehearsal. A bigger earthquake, they say, is on its way, probably sooner rather than later.