Earthquake safety: LA orders inventory of vulnerable buildings (Updated)
The Los Angeles City Council on Wednesday approved a motion that will create three new positions dedicated to cataloging the city's wood-frame "soft story" buildings, which may be vulnerable to damage in an earthquake.
This type of structure is usually a multi-unit apartment with open parking or commercial space on the first floor and housing on upper levels. It's particularly vulnerable to collapse during strong shaking.
The motion, which passed unanimously, asks the Department of Building and Safety to set aside roughly $382,000 to hire one structural engineer and two building inspectors.
The team will need a little over a year to inspect and categorize the 29,226 buildings built before 1978 that were identified by the department in a previous report. After 1978 building codes were improved.
"We have to do this. There will be another earthquake," said City Councilman Tom LaBonge, who sponsored the proposal.
Soft story buildings built before 1978 are a hot issue for those looking to improve seismic safety. During the 1994 Northridge earthquake, the soft-story Northridge Meadows apartment complex collapsed, killing 16 people.
Last year, the City of San Francisco enacted legislation requiring the owners some 3,000 soft story buildings to retrofit their structures to make them safer. LaBonge says he will travel to San Francisco this fall to meet with officials to learn from their efforts.
Cataloging vulnerable buildings will be a challenge.
LaBonge says the team will use Google Maps and other methods to sort the buildings and label them as either non-soft story, soft-story or buildings that cannot be identified as either non-soft story or soft-story.
The city estimates that there are at least 5,800 soft story buildings but more may turn up as the inspection is carried out.
After the list is completed, LaBonge hopes to work with state officials to create a program to offer low interest loans to homeowners looking to retrofit their structures.
"I think it's a very good, big day in our efforts," LaBonge said. "We've got to first base, but you've still got to get to second, third... and home. We want to score for Los Angeles and make it safe."
Tom Heaton, a professor of engineering seismology at Caltech, said today's action was an important first step. But he added soft story buildings are only one type of structure known to be vulnerable to large quakes.
"In terms of the greatest hazard to L.A., I suspect old concrete frame buildings are a bigger hazard," Heaton said.
Often referred to as "non-ductile concrete buildings," this type of structure has stiff concrete frames that don't bend easily when shaken, increasing the chances of failure during an earthquake.
University of California researchers have identified 1,454 such structures in Los Angeles, including apartment buildings, schools, offices, churches, shopping malls, hospitals and hotels .
Caltech's Heaton noted that while concrete buildings may be a bigger threat to public safety, they are also much harder to inventory and retrofit. In comparison, working with soft story buildings is relatively straight forward, he said.