More than 1,000 old concrete buildings in Los Angeles and hundreds more throughout the county may be at risk of collapsing in a major earthquake, according to a Times analysis.
By the most conservative estimate, as many as 50 of these buildings in the city alone would be destroyed, exposing thousands to injury or death.
A cross-section of the city lives and works in them: seamstresses in downtown factories, white-collar workers in Ventura Boulevard high-rises and condo dwellers on Millionaires' Mile in Westwood.
Despite their sturdy appearance, many older concrete buildings are vulnerable to the sideways movement of a major earthquake because they don't have enough steel reinforcing bars to hold columns in place.
Los Angeles officials have known about the dangers for more than 40 years but have failed to force owners to make their properties safer. The city has even rejected calls to make a list of concrete buildings.
In the absence of city action, university scientists compiled the first comprehensive inventory of potentially dangerous concrete buildings in Los Angeles.
The scientists, however, have declined to make the information public. They said they were willing to share it with L.A. officials, but only if the city requested a copy. The city has not done so, the scientists said.
Recent earthquakes have spotlighted the deadly potential of buildings held up by concrete. A 2011 quake in Christchurch, New Zealand, more than two years ago toppled two concrete office towers, killing 133 people. Many of the 6,000 people killed in a 1995 earthquake in Kobe, Japan, were in concrete buildings.
In 1971, the Sylmar earthquake brought down several concrete structures, killing 52. Twenty-three years later, the Northridge earthquake wrecked more, including a Bullock's department store and Kaiser medical office.
Seismologists said a bigger earthquake is overdue.
"We know darn well that if a bunch of people die, there will be lots of stories, lots of reports, things will change," said Thomas Heaton, director of Caltech's Earthquake Engineering Research Laboratory. "But the question is, do we have to have lots of people die in order to make this change?"
In the Roaring '20s, concrete buildings helped transform the Los Angeles skyline, as office towers and apartments rose from the city's landscape.
By the 1970s, canyons of concrete towers lined some of L.A.'s most famous streets: Wilshire, Hollywood, Sunset, Ventura, Main and Broadway. They include landmarks such as the Capitol Records tower, the Hollywood Plaza apartments and the W Hotel in Westwood, according to city records.
A team of Los Angeles Times reporters mined thousands of city and county records to identify older concrete buildings. The Times found more than 1,000 buildings in Los Angeles and hundreds elsewhere in the county that appeared to be concrete.
Reporters walked through seven L.A. business districts to gauge the accuracy of the list. They pulled building permits and sent questionnaires to dozens of property owners, asking them to review the details. In these areas, The Times found 68 older concrete buildings, according to public records. Of those, just seven had been retrofitted, or strengthened to survive large earthquakes. The reporters' work covered a fraction of the older concrete structures in the city.
The survey showed the difficulties of accurately identifying concrete buildings. Some city records didn't specify the construction materials used. Some buildings that appeared to be made of concrete turned out to be steel framed, while others that appeared to be brick or steel were concrete.
Hollywood — which is bisected by a fault capable of producing a 7.0 earthquake — has one of the biggest concentrations of concrete buildings. In a few blocks around Hollywood Boulevard and Vine Street, The Times found 14 concrete structures built before 1976, when city codes started requiring more steel rebar. Only three have been retrofitted.
The story is much the same on a stretch of Ventura Boulevard in the Encino area. The Northridge quake battered several concrete buildings in the district, including a 10-story hotel. Owners spent $4 million to better protect it in an earthquake. Out of 10 concrete buildings on that section of the street, only the hotel and one other structure have been strengthened.
In two downtown neighborhoods, along Broadway and Santee Street, The Times found 17 concrete buildings. None had a record of retrofitting.
One of those buildings is owned by Scott Kim's family. When they bought the five-story factory for their sewing supply business, Kim said, they didn't think to have it examined by a structural engineer.