The state Legislature recently voted to require that cities and counties create lists of buildings that are most likely to collapse during an earthquake. The goal is to make Californians more aware of the dangers of seismically vulnerable buildings.
Assembly Bill 2681 was sent to Gov. Jerry Brown on Sept. 5. The bill states: "California contains thousands of buildings that are known to present an unacceptably high earthquake risk of death, injury and damage." The authors of the bill cite estimates that a major quake along the San Andreas fault could lead to at least 1,800 deaths and cause more than $200 billion in damages.
Could USC buildings end up on the list?
John E. Vidale, the director of the Southern California Earthquake Center, said USC is located in a seismically active area. "There are faults all through the ground under our feet."
Vidale points out that including the USC area, Los Angeles is vulnerable to damage in an earthquake because the ground is so soft. "Although USC is not the softest place in the city, it is certainly not firm ground. Soft ground amplifies the motions," he said.
Because of the soft ground, people can feel earthquakes from a considerable distance. If there is an earthquake near UCLA, it would still shake strongly at USC due to the soft ground, Vidale said.
In spite of the location, Vidale gives a positive outlook on the seismic resistance of USC buildings. "A serious earthquake is infrequent," he said, and construction materials and techniques have improved in the years since earlier major quakes in Southern California in 1971 and 1994.
"Actually, the majority of the buildings are not that easy to collapse during earthquakes," he said. "People don't know how safe their buildings are."
Erik Johnson, a USC professor of civil and environmental engineering, also explains that some types of buildings are safer than in the past. Brick masonry buildings often collapse during earthquakes because "the vertical loads are held primarily by the brick," he said.
But, unlike 50 years ago, when most buildings were primarily made of brick, today's buildings are safer due to improvements in structural materials.
"Today the core is steel or concrete or wood, and the brick is just a facade on the outside. We see the bricks outside the building. It doesn't mean it is unsafe," Johnson said.
He cites Webb Tower, which is located at USC near Gate 5, as an example of that.
"There are some external 'X' braces in each floor, and those braces can be added to strengthen for earthquake retrofit."
Although most USC buildings are safe, Vidale said, students should still be aware of the dangers of earthquakes. He suggests that students should participate in the upcoming earthquake "Shakeout Drill" on campus on Oct. 18.