It was exactly 5:04 p.m.
Most people in Northern California weren't thinking about plate tectonics or the San Andreas Fault that Tuesday. They were thinking about baseball. It was October 17, 1989, and the "Battle of the Bay" World Series between the Oakland Athletics and the San Francisco Giants was about to start Game 3 at Candlestick Park. Then, the ground didn't just shake; it heaved. For fifteen seconds, the earthquake in 1989 in california—now officially known as the Loma Prieta earthquake—ripped through the region with a magnitude of 6.9.
The images are burned into the collective memory of anyone alive then. The Nimitz Freeway pancaking. A section of the Bay Bridge falling like a toy. Smoke rising over the Marina District. Honestly, it's a miracle the death toll wasn't higher. Because the game was about to start, thousands of commuters had left work early to get to a TV or the stadium. The normally packed I-880 was eerily empty compared to a standard rush hour. That fluke of timing probably saved hundreds, if not thousands, of lives.
The Science of the Slip
We usually talk about earthquakes as things that happen "to" us, but the mechanics are fascinatingly violent. The epicenter was near Loma Prieta peak in the Santa Cruz Mountains. This wasn't a standard "side-to-side" slide. It was a slip-offset. The Pacific Plate moved 6.2 feet to the northwest and pushed 4.3 feet over the North American Plate.
That upward thrust is why the Santa Cruz Mountains actually grew a bit that day.
But why did San Francisco, miles from the epicenter, get hit so hard? It comes down to dirt. Or, more specifically, "liquefaction." Much of the Marina District and the areas near the Embarcadero are built on reclaimed land—basically mud, loose sand, and debris from the 1906 quake. When the shaking started, that soil acted like a liquid. Buildings didn't just shake; they sank and tilted. You’ve probably seen the photos of four-story apartment complexes reduced to three because the first floor simply evaporated into the muck.
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The Cypress Structure Tragedy
If there is a dark heart to the earthquake in 1989 in california, it’s the Cypress Street Viaduct in Oakland. This was a double-decker stretch of Interstate 880. When the waves hit, the support columns failed. The top tier collapsed onto the bottom tier.
Forty-two people died there.
It remains the deadliest aspect of the entire event. Engineers later found that the structure was built on soft clay, which amplified the vibrations. The "resonance" of the soil matched the vibration of the bridge. It’s a terrifying concept in physics—when the frequency of the ground matches the frequency of the building, the energy doesn't dissipate. It multiplies.
Rescue workers spent days crawling through gaps barely two feet high, using chainsaws and jackhammers to reach trapped motorists. Buck Helm, a local clerk, became a symbol of hope when he was pulled out alive after being trapped for 90 hours. Tragically, he passed away a few weeks later, but his rescue remains one of the most intense moments of the recovery effort.
The World Series Connection
You can't talk about Loma Prieta without talking about Al Michaels.
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The ABC broadcast was just beginning when the signal started to flicker. Michaels' voice famously cut out as he said, "I'll tell you what, we're having an earth—" and then the screen went to static. Because it was a national broadcast, the entire country saw the disaster happen in real-time. It was perhaps the first time a major natural disaster was experienced "live" by a global audience before social media existed.
The game was postponed, obviously. But when it resumed ten days later, the atmosphere was somber. The A's eventually swept the Giants, but nobody really cared about the rings. The "Battle of the Bay" had turned into a battle for the Bay’s survival.
Hard Lessons and Retrofitting
California changed its building codes almost overnight.
If you walk through San Francisco today, you’ll see giant X-shaped steel braces on the outside of old brick buildings. That’s a direct result of 1989. We realized that "unreinforced masonry" is basically a death trap. The state spent billions—literally billions—retrofitting bridges. The new eastern span of the Bay Bridge, which replaced the one that broke in '89, is designed to withstand the "Big One" without collapsing.
Is it enough? Geologists at the USGS (U.S. Geological Survey) say there is a 72% probability of a magnitude 6.7 or greater earthquake hitting the Bay Area before 2043. Loma Prieta wasn't even the "Big One." It was a "medium one" that happened to hit a vulnerable spot.
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What You Should Actually Do
Most people have a "quake kit" that consists of a dusty bottle of water and a granola bar from 2012. That won't cut it. Based on the data from the earthquake in 1989 in california, the biggest threats aren't just the shaking—it's the aftermath. Fires broke out in the Marina because gas lines ruptured and water mains broke. Firefighters had to pump water directly from the Bay.
Here is the reality of what you need:
- Water is everything. You need one gallon per person per day. Aim for a 14-day supply.
- The "Shoes Under the Bed" Rule. This is the most common expert advice. If a quake hits at 3 a.m., the floor will be covered in broken glass. If you can't find your shoes, you're stuck. Tape a pair of old sneakers and a flashlight to the leg of your bed.
- Secure the heavy stuff. In '89, many injuries were caused by falling bookshelves and televisions. Use furniture straps. It feels like a chore until the room starts jumping.
- Learn your shut-offs. Do you know where your gas main is? Do you have the wrench to turn it off? If you smell gas after a shake, you need to act in seconds, not minutes.
The 1989 earthquake proved that infrastructure is fragile. The Bay Bridge was closed for a month. The Cypress Viaduct was never rebuilt; it was turned into a ground-level boulevard. We learned that the ground beneath our feet isn't nearly as solid as we like to pretend.
If you live in a seismic zone, the best way to honor the memory of those lost in 1989 is to be the person who is actually prepared when the next one hits. Because it will hit. It’s just a matter of when the clock starts.
Practical Next Steps for Residents:
- Check your home's "soft-story" status. If you live in an apartment with a garage on the first floor, ask your landlord about seismic retrofitting status.
- Download the MyShake app. It provides several seconds of warning before the S-waves hit, which is enough time to get under a sturdy desk.
- Audit your emergency kit tonight. Replace expired food and check the batteries in your radio.
- Identify your "out-of-state contact." Local cell towers often jam during a disaster, but long-distance texts sometimes get through when local calls won't.