Other destructive quakes would follow — Long Beach in 1933, Sylmar in 1971, Loma Prieta in 1989 and Northridge in 1994. But none compared to 1906, which left 3,000 people dead and, combined with the subsequent fire, more than 80% of the city of San Francisco destroyed.
More than a century later, California is still dealing with that legacy. Some cities are now in the midst of new efforts to retrofit buildings to better protect them during a major quake. These efforts are far from uniform across California — and experts say they still leave many people and buildings vulnerable.
Here is a breakdown of what is being done — and what isn't.
Los Angeles is the largest of a few cities to tackle what officials consider one of the most dangerous types of buildings. A law requires the retrofitting of hundreds of brittle concrete buildings, one of the most vulnerable types of structures in California. But experts have worried that a major earthquake will hit Southern California before the deadline to fix these buildings comes. These buildings were the subject of a 2013 Times investigation.
There is a 60% chance that a magnitude 6.7 earthquake — the size of the 1994 Northridge temblor — or larger will strike the Los Angeles area in the next 30 years, said U.S. Geological Survey geophysicist Morgan Page.
L.A.'s effort is now hitting a key milestone, with the city issuing orders to owners of roughly 1,500 concrete buildings in Los Angeles believed to be at risk, which dot the city in downtown, the Westside, the San Fernando Valley and elsewhere.
For property owners who receive the orders, the financial toll could be considerable. Retrofitting could cost millions of dollars. There are no public subsidies available to help pay for the work. Some owners have expressed concerns about how they will pay.
The deadly nature of brittle concrete buildings became clear in Los Angeles nearly half a century ago, when 52 people died in the collapse of several concrete structures, including hospital buildings, in the 1971 Sylmar earthquake. Concrete buildings fell again in 1994 during the Northridge quake. Efforts in the 1990s to fix the buildings died amid concerns from property owners about the costs.
Earthquake experts say that as many as 50 brittle concrete buildings in the city of L.A., housing thousands of people, could collapse in an earthquake. Which buildings collapse depends in part on where the earthquake strikes and how big it is.
‘Soft story’ apartments
Los Angeles and San Francisco — and a few smaller cities — are requiring retrofits of these wood-frame apartments with weak first stories.
Los Angeles inspectors spent about two years developing a list of 13,500 so-called soft story buildings that will probably need seismic strengthening. These apartments, which feature flimsy first floors that often serve as parking spaces, became popular after World War II as Los Angeles was spreading north into the San Fernando Valley and west toward the ocean.
But they've also proven to be vulnerable to violent shaking. Such buildings collapsed in the 1989 Loma Prieta earthquake and the 1994 Northridge earthquake, including one apartment building where 16 people died.
Owners of each building have been put on notice, and a number of them have already begun the retrofitting process. The retrofits can cost as much as $130,000, which has sparked concerns from owners and residents feeling the pressure of rising rents and a housing crunch.
Other cities dealing with this include Santa Monica, West Hollywood and Berkeley.
While single-family homes have traditionally been seen by experts as less likely to be deadly in an earthquake, deaths are still possible, and the financial consequences can be catastrophic.
Homeowners who endure major damage can face a bill of hundreds of thousands of dollars and years of living out of their home to repair the damage — all while still paying the mortgage, experts say. Only about 10% of California homeowners have earthquake insurance.
Some Californians have begun to pursue earthquake retrofits for their single-family homes, taking advantage of a grant program that has been funded by the California Earthquake Authority and the state Legislature.
Particularly vulnerable are homes of a type typically built before 1979, with a handful of steps above the ground.
There's a problem when the house is attached to the foundation by a flimsy, short wall — known as a "cripple wall" — that creates a crawl space. This wall and the wood beams that keep the house off the ground often have not been fastened tightly to the foundation.
So in an earthquake, the lack of grip between the house and foundation can cause the home to be shoved off — as if the shaking has broken the building's knees.
It can be a costly repair — raising the home many feet into the air and pouring a new foundation before lowering the house back down. Homeowners in many California earthquakes, from the 1971 Sylmar earthquake to the 2014 Napa earthquake, have suffered such damage.
California learned the dangers of brick construction when a major earthquake struck Long Beach in 1933, crumbling schools, churches and shops. Some 120 people died. These so-called unreinforced masonry buildings, or URMs, are vulnerable because the mortar essentially crumbles during shaking, bringing down the roof and walls.
Cities across California now ban this type of construction. URMs that had already been built were mostly left to fate. But as its history of destruction continued — Sylmar in 1971, Loma Prieta in 1989 — a number of cities found the political will to compile a list of addresses and force owners to either demolish or add reinforcement to their brick buildings.
In Los Angeles, after three decades of chasing down the owners of 8,080 URMs, officials say there are now only three left in the city that still need to be retrofitted or demolished. When the Northridge quake struck in 1994, the retrofits proved lifesaving: Not a single person died in a brick building.
When a magnitude 6.5 earthquake in 2003 struck downtown Paso Robles, the two people who died were found crushed under an avalanche of bricks outside an unretrofitted historic building. The roof had slid onto the sidewalk, taking the clock tower with it. (The city, which had a retrofit law on the books, had given the owner until 2018 to complete the seismic strengthening.)
But one region is particularly behind.
A Times analysis earlier this year found that as many as 640 buildings in more than a dozen Inland Empire cities, including Riverside, Pomona and San Bernardino, have been marked as dangerous. But they remain unretrofitted despite decades of warnings, according to a Times analysis of the latest building and safety records. These cities are far behind coastal regions of California, which have retrofitted thousands of buildings after devastating earthquakes exposed how deadly they can be.