In the three days after the Northridge Earthquake, sociologist Paul O’Brien trekked to the epicenter to collect survivors’ stories. He spoke with 31 survivors, some over the phone, but for the most part, he met people where they were lodging during those first few days and nights: on the street.

“One could not drive down any street in the Northridge section of town, and not find tents staked out on lawns, in parks, and anywhere else residents could find room,” he wrote in a research report published the same year.

Twenty five years later, experts still look back at Northridge to prepare for the inevitable: The next “Big One” will force hundreds of thousands of people out of their houses. How authorities respond to the crisis will largely determine the number of people displaced—and how long they will have to wait until they can return to home.

“It is a bit daunting if we were to have the Big One, just because LA is so big and so densely populated,” said Sonya Young-Jimenez, an emergency management coordinator for the city’s recreation and parks department, which shoulders the immense task of identifying and assessing sites for potential disaster shelters. “We’re talking hundreds of thousands of people being affected.”

The impact will be felt more intensely for some Angelenos than for others. It’s expected that those who can afford it will either flee or profit, increasing the value of their homes through renovations made with insurance payouts. Those who can’t will be left with fewer resources to pick up the pieces.

What unfolds in the aftermath could permanently change LA’s demographics, potentially exacerbating the gap between the rich and poor and even causing regional depressions. A short-term shelter crisis could evolve into a long-term community-building crisis. The general anxiety reported after natural disasters could result in so many people moving away that businesses shutter.

In 2008, a team of scientists from the U.S. Geological Survey used complex computer models to simulate what would happen if a 7.8 magnitude earthquake struck the San Andreas fault.

The report, titled ShakeOut, estimates that quake would kill 1,800 people; rupture 966 roads, 21 railroads and 32 aqueducts; down 141 power lines; and damage 300,000 buildings.

As many as 270,000 people across Southern California would be displaced from their homes. About 500 public shelters would be needed to house roughly 175,000 of those people—nearly double the population of Santa Monica—because they wouldn’t be able to find shelter with family or friends or in hotels.

The biggest issues first responders and evacuees will face won’t be the ones caused by the quake itself. The real trouble will start after the ground stops shaking, said Lucy Jones, seismologist and author of The Big Ones: How Natural Disasters have Shaped Us.

Fires, water shortages, limited transit, job accessibility, and communication outages like the loss of cell phone service will exacerbate the damage and displacement.

“You get this compounding problem,” said Jones. “The economic system works because we all feed on each other. If employees aren’t going to work, then they’re also not going to eat at the nearby restaurant. Every one individual job has impact.”

Today, rising temperatures and changing intensity of winds could potentially be survivors’ worst enemy. As Jones laments, the Santa Ana Winds could stoke fires sparked by the quake, into fires not unlike the Woolsey and Camp Fires at the end of 2018.

Those issues could be complicated by the current homelessness crisis, leaving hundreds of thousands of Angelenos without temporary or even short-term shelter.

Officials are acutely aware that LA’s worsening housing shortage could raise the number of people displaced after a disaster. If hundreds or thousands of housing units were made uninhabitable due to earthquake damage, even more people would be searching for new places to live.

Last year’s horrific wildfires are a tragic example, with tens of thousands of people displaced from the Camp Fire swamping the city of Chico.

The fires have presented incoming California Gov. Gavin Newsom and his office of emergency services an opportunity to change the way the state responds and delivers aid.

“That we still have a lot of people in shelters is indicative that we’re still learning,” said Tina Curry, the department’s deputy director of planning and preparedness. “But sometimes shelter operations can be extended and we’ll have to learn to support that.”

A loss of housing after the Woolsey Fire has created a surge in renters and spikes in listings, forcing the city of Malibu to put price gouging rules into place indefinitely.

Hefty payouts from insurance companies also fuel the problem. Updating insurance policies to a loss-of-use type is an effective way to prepare for a disaster, but as Jason Ballman, communications manager at the Southern California Earthquake Center emphasized, it also has priced people who don’t have insurance, or can’t afford it, out of the game.

In the case of Malibu and the Woolsey Fire, “some people who lost homes—and could afford it—simply left the country for the rest of the year,” Sandro Dazzan, real estate agent with The Agency told The Real Deal.

In 1994, people who could afford it named the earthquake as the catalyst for leaving California for good, as the New York Times chronicled that year. As experts point out, and as the Los Angeles Times has reported, the population in Los Angeles has only ever dipped four times—two of those times occurring in the years following the Northridge quake.

If Californians were to flee, all eyes are on Arizona as the most probable state to absorb SoCal’s potential refugees—so much so that Phoenix leaders spent the latter part of 2018 running drills in the event that the Big One does come.

But what happens to those who choose not to leave?

Data collected after Northridge indicates people will head outside, to parks, open areas, anything away from a building, as long as it’s relatively near their own homes.

The recreation and parks department is preparing for many people to form tent camps in open spaces or on their front lawns. Official shelters, like those operated by the Red Cross and other agencies, will be set up in recreation facilities and public buildings.

“We do assessments of all our sites,” said Young-Jimenez. “And our partner is the Red Cross. Every week they’re assessing something. It’s pretty much ongoing.”

For many others, staying in LA will not be a choice.

“One statistic claims that for affluent white men, it takes an average of seven days to return home post-disaster, but for poor women of color, it takes an average of seven years,” said ShakeOut co-author Dennis Mileti, retired sociologist and director emeritus of the Natural Hazards Center at the University of Colorado at Boulder, citing findings published by natural disaster sociologist Robert Bolin after the Whittier Narrows Earthquake in 1987.

“I keep telling people: Stop worrying about the earthquake killing you, start worrying about the earthquake bankrupting you.”

Young-Jimenez’s department is using software that layers socioeconomic data on top of geographic and seismic data to model potential scenarios. The models can be used to identify how poorer areas of the city—those with older homes that most likely haven’t been retrofitted—would be affected by a major earthquake, in comparison to more affluent areas.

The reality is that earthquakes are indiscriminate. As Jones puts it: “Earthquakes shake everybody.”

But because of the difference in quality of infrastructure and lack of accessible resources people in lower-income communities face, the effects are often not.

“If you’re poor, you’re more likely to live in substandard housing, and be in a job that says to you, ‘Oh hell, give up,’” Jones said. “I keep telling people: Stop worrying about the earthquake killing you, start worrying about the earthquake bankrupting you.”

It’s also essential to consider where people come from, said Joselito Garcia-Ruiz, regional disaster program officer for the Red Cross’s LA Region.

“I came to work during Northridge, and I saw with my own eyes that many people from Central America and Mexico at that time were afraid to go inside the shelters, because they came from the ’85 earthquake in Mexico and they brought with them that experience,” he said.

While the long-term effects of a major quake could forever alter the economic and cultural landscape of Los Angeles—potentially sending its most vulnerable communities into economic depression while more affluent residents flee—there may be another surprising outcome.

Natural disasters are also good at knocking down social barriers.

Those unplanned shelters that popped up in 1994 were established not only out of convenience, but because of the bonds that had formed across walls both real and socially constructed. People—neighbors who may not have known each other until their homes were destroyed—wanted to be near each other.

“Even people who before a disaster hated each other, will end up hugging and kissing each other,” said Mileti. “It brings the best out in humanity.”