When the Northridge quake hit there was no warning, no way to tell how long before the shaking would start and no way to know just how violent it would be. But 20 years later, the technology is ready and experts are convinced a warning system would save lives.
"If you were getting surgery, you might want the doctor to know that things were about to shake hard. If you're riding in a train, you would probably want that train to slow down and stop. If you were on an elevator, you would want it to stop at the next floor and open up the doors," said Doug Given, Caltech earthquake early warning coordinator.
Caltech has been testing the ShakeAlert system since 2012, and they say so far it works. The only thing keeping it from becoming operational is government approval and about $23 million in funding to get it started.
How much warning you get depends on your proximity to the earthquake. Best case scenario, it could be up to a minute. That's plenty of time to get to safety. A similar alert system has been in use in Japan for years.
"The public was polled about their opinions about those warnings, and about 90 percent say it's very worthwhile," said Given.
Simulations help scientists predict how a big quake would affect a crowded urban area. New building standards could also give Californians a better chance the next time the ground starts to shake. The 6.7 quake toppled and pancaked buildings across the region, and sent freeway bridges crashing to the ground.
Following Northridge, freeway retrofitting projects were accelerated into high gear. Bridges and overpasses have all been reinforced to deal with big quakes.
Yet experts still see plenty of room for improvement, especially with older buildings in many parts of Los Angeles.
"It's just like real estate: location, location, location," said Thomas Heaton, an engineering professor at Caltech. "So if we had the same earthquake and we put the heavy shaking that was in the northern San Fernando Valley, and we put it downtown or the Mid Wilshire to West L.A., it would still be a tremendous disaster."
Heaton worries most about concrete frame buildings. One Caltech building in particular has been heavily reinforced. That building has several windows on the first floor.
"We put in walls at every corner. So if you look behind this window, you'll see the windows actually open to a concrete wall," said Heaton.
But many buildings have no reinforcement and there are no current plans to fix them. Heaton believes at the very least, tenants and landlords should be told the risks with some type of safety rating.
"When it comes to buildings, the general population has no clue about what's a good building and what's a bad building," Heaton said.
While Los Angeles is safer 20 years after Northridge, everything depends on where the next big quake will hit and what kind of building you're in.