OAKLAND, Calif. (KTVU) - At 5:04 p.m. 29 years ago, the Loma Prieta earthquake struck the Bay Area. 63 people died and more than 3,000 were injured.
The 6.9 magnitude quake sparked more than 40 fires and caused nearly $7 billion in damage. Buildings crumbled. Homes collapsed. The Marina District was hit especially hard, because it was built on a landfill.
"With the lateral forces from the earthquake, bayfill, or mud, tends to become more liquid and when that happens foundations of buildings, that are set in what had been bay mud, become weak and can fall," said William Strawn with San Francisco's Building Inspection Department.
Strawn says for that reason, city leaders mandated retrofitting for more than 5,000 buildings identified as soft story buildings, which have a garage or storefront on the ground level.
"So the whole point of the retrofitting program is to add strength to that ground floor level so you'll have a stiffer resistance and it won't just fall apart in that way," said Strawn.
More than 50 percent of those structures are complete. Many others are about two years away.
We're told $75-80 billion has been invested in retrofitting since 1989, making the city better prepared.
Not all San Franciscans are quite there yet.
"A lot of people I talk to have emergency backpacks. They have a plan on where they will go if one starts so I should probably figure that out," said Courtney Braasch of San Francisco.
Lucky for her, the U.S Geological Survey just announced Wednesday the rollout of an earthquake early warning system called Shake Alert.
"Once we locate the earthquake and get an estimate of the earthquakes magnitude we can broadcast that information electronically ahead of the earthquake to points where the earthquake hasn't been felt yet so those people will get a warning," said Tom Brocher, a seismologist.
A heads up of up to a minute is possible for larger quakes and about 10-20 seconds for other quakes.
They're crucial seconds needed to save lives.
California Shake Out is Thursday morning at 10:18 a.m. where people will practice the "drop, cover and hold on" drill.
Sunday, marks the 150th Anniversary of the Great earthquake along the Hayward fault.