City Has At-Risk Buildings During Earthquake
Posted by Amanda Macke on Oct 16, 2013 - 3:16:18 PM
HOLLYWOOD HILLS—A Los Angeles Times report released on October 13 found that
Hollywood has the largest quantity of old buildings vulnerable to collapse during a major earthquake and has spurred two
Los Angeles council members to act. The in-depth investigative report found that “more than 1,000 old concrete buildings in
Los Angeles and hunÂdreds more throughout the county may be at risk of colÂlapsing in a maÂjor earthÂquake.”
Hollywood, a city with its own fault line, was discovered to have one of the highest concentrations of high-risk buildings.
Canyon News spoke with Tom Heaton, the Director of the Cal Tech Earthquake Engineering Research Lab, who defined these high-risk buildings as “old concrete buildings with column frames.” These old concrete, column-framed buildings are susceptible to the sideways movements of an earthquake and therefore need to be retrofitted, or reinforced with bars to protect them from collapse. Heaton said these “non-ductile” or “brittle” buildings “cannot take much damage” and “once the building starts to fail, it all fails.”
Tower, Hollywood Plaza Apartments, Pantages Theater and Knickerbocker Apartments were among the 14 old concrete
Hollywood buildings found to have no records of seismic retrofit. Only three of the 14 old concrete structures had been retrofitted for earthquake safety in the blocks around
Hollywood Boulevard and
Vine Street, according to the report.
The Pantages Theater is one of the high-risk Hollywood buildings.
Heaton explained that
Hollywood has a lot of these old, brittle buildings because the city was growing during a time when people didn’t yet understand the flaws of these structures. “The defect [in the old buildings] showed up in the 1971 earthquake in the northern part of the
San Fernando Valley,” Heaton said. The Los Angeles Department of Building and Safety (LDBS) issued important changes to the 1976 building codes in response. “The problem was in
Hollywood, lots of these buildings were already built,” Heaton explained.
Luke Zafarani, Chief of the LDBS, told the Canyon News that the agency upgrades their codes every three years but that those codes are only effective from that point on. That means, for example, an industrial building that converted into residential housing prior to the 1976 codes may still have a design that is not strong enough to sustain an earthquake.
According to Zafarani, the LDBS only has the authority to regulate existing buildings “that want to change the use of the building or make changes that would exceed 50 percent of the building’s value.” The LDBS cannot force owners to upgrade the structural integrity of their high-risk buildings and instead offers a voluntary retrofitting program.
The problem is that building retrofits are a very costly, time-consuming venture that many owners either will not or cannot afford. The Los Angeles Times estimated only about 100 buildings have voluntarily elected to retrofit their buildings.
Major fault lines in Southern California.
“The problem that is most concerning is the general populous does not know if they are occupying one of the buildings that are at risk because there is no publically available list,” said Heaton. The list created by the Los Angeles Times is only an educated estimate and the
Center from UC Berkley will not publically release their list for risk of lawsuit.
Zafarani explained that it is difficult to create an accurate list because there is no way to know the true construction of a building without having a specialized structural engineer come in and inspect each building. The LDBS has never been commissioned to make such a list, and “if we were mandated to do so we would need to hire more people to do it which could be very expensive,” Zafarani said.
On Tuesday, October 15, Los Angeles Councilmen Tom LaBonge and Bernard Parks issued requests for city agencies to explore the feasibility of creating a list of high-risk buildings, according to media reports.
“If a list was made of these buildings, that step alone would put a lot of pressure on building owners to prove the buildings were not dangerous,” Heaton said.
The last major earthquake in the region was the 1994 Northridge earthquake, nearly twenty years ago. According to Heaton,
Los Angeles only felt “a glancing blow” of the heavy shaking taking place in the northern
San Fernando Valley. “The 1994 Northridge earthquake would have been three to four times stronger if it was placed there in
Hollywood,” Heaton said. “Many fragile buildings would have been expected to collapse.”
Heaton added that no one can predict when or where the next damaging
California earthquake will take place. “We do know a big one will happen, and would prefer engineers were able to say it is going to be hard to knock this building down and not for engineers to be unsure about it,” said Heaton.