High stress levels on fault lines under Los Angeles could increase risk of an earthquake in the near future, according to a June study by University of Hawaiʻi at Mānoa researchers.
Tectonic stress build-up in the northern part of the Cajon Pass – where the San Andreas and San Jacinto Faults converge – is higher than ever before, according to the June study. The research drew data from simulations of the last 1,000 years of earthquakes.
The two faults, which lie under LA and have not ruptured together since 1812, have endured additional stress since the last rupture.
“Part of why we have mountains and it’s such a beautiful place to live, is because we have a plate boundary, and there are earthquakes,” said Scott Brandenberg, a professor of civil and environmental engineering. “We just need to know about that and be ready.”
Jonathan Stewart, the Sabol-Scott Term Chair in Civil and Environmental Engineering at the UCLA Samueli School of Engineering, said the results of the June study will allow people to understand how faults work. However, it does not mean that people are less safe than before, he added.
The Seismic Safety Program – which oversees University-wide guidelines to evaluate buildings and set safety standards – is working with UC campuses to identify and address the most vulnerable buildings, Stewart said.
“Safety comes down to mainly the quality of the buildings we live in and the quality of the infrastructure we rely on,” said Stewart, the vice chair of the UC Office of the President’s Seismic Advisory Board.
Cost is a major barrier in strengthening building structure, Brandenberg said.
The LA City Council passed a seismic retrofit law in 2015, mandating that structures built before 1978 with weak or open front wall lines and older types of concrete be improved.
Strengthening building structure also has sustainability implications, Brandenberg said.
“It seems like we should always be all for safety,” Brandenberg said. “But there are costs, and there’s carbon footprint. If somebody tears down a building and rebuilds it, that’s a lot of new construction materials.”
Limited state funding has also been a challenge for the Seismic Safety Program, Stewart said. The estimated construction costs for seismic improvement across all campuses is $6.7 billion, according to the UC’s Seismic Safety Funding Overview.
UCLA’s off-campus buildings have less earthquake support – especially its smaller medical clinics across LA, Stewart said.
“UCLA’s portfolio as a whole has a lot of seismic vulnerabilities,” he said. “But when we just look at the campus where the students are, they’ve done a good job, given the resources they have, at trying to bend the arc of earthquake resilience in the right direction.”
Alton Wu, a rising fourth-year civil engineering student said he is not concerned about the June study’s results because he has seen structural engineering firms fortify vulnerable buildings first-hand.
“We’re not waiting for a big earthquake to come,” said Wu, who works at structural consulting firm Saiful Bouquet. “We’re always designing for that earthquake, so I’m not too worried if an earthquake hits.”
However, Wu said he believes some firms in the structural engineering industry reinforce buildings too late.
“People don’t care until it (an earthquake) happens, and then when it happens, then people are putting money into fixing it,” Wu said. “You’re being reactive as opposed to proactive, which is why we always need to be paying attention.”
Having enough drinking water in preparation for an earthquake is important because potential sewer line leaks could contaminate tap water, Stewart said. An earthquake from the San Andreas fault could cut off major aqueducts, which transport water, he added.
Brandenberg added that people should secure their furniture before an earthquake, and store canned food because transportation and services could be disrupted.
People should drop down and cover themselves to protect their bodies during an earthquake, Brandenberg said.
“Studies like this one that show that the stresses are actually pretty high based on the modeling … and maybe bring earthquake safety to the forefront again,” Brandenberg said.
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