Science + Technology

The evolution of earthquake science

UCLA scientists are helping California prepare for catastrophe

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Jonathan Stewart
Timothy Archibald/UCLA Magazine

Jonathan Stewart, a professor in the UCLA Department of Civil and Environmental Engineering, at a Los Angeles Department of Water and Power facility.

It's a scene of post-mayhem disaster. In front of the Acacia residential building on the west end of the UCLA campus. Victims are everywhere, bleeding, confused, in and out of consciousness. A small boy in a baseball hat and shorts is laid out on a red tarp. “Very low pulse,” says one of the people who helped carry him over, before rushing back to the search and rescue. It’s hard to tell if anyone hears her, given the commotion. Nearby, a woman sits upright, a drop of blood rolling out of her ear and down her cheek, and another woman props her bloodied leg inside a makeshift cardboard splint.

A few dozen first responders move victims onto colorcoded tarps — green for the most stable, yellow for those in need of a medic and red for the most critical. One of the vested first responders kneels beside the boy to check his pulse, and quickly stands up again. “We have a dead over here,” she calls out. But there’s no time to stop.

This is the aftermath of a 6.8 magnitude earthquake centered on the Santa Monica Fault just south of campus. It’s the “big one” that Southern Californians had known could one day happen. That day is today.

Except it’s not. The “victims” are all actors, the injuries painted on and the small boy alive and well. The first responders are volunteers from the Community Emergency Response Team, running a drill to test emergency response procedures on campus.

While this 6.8 quake didn’t actually happen, through the work of researchers and scientists across UCLA, we know with certainty the probable impact of such a temblor, how to warn those who would feel its shaking, how to plan around its destructive power and even how to ensure that buildings like the Acacia dorms don’t fall. From the deepest motions of our planet’s structure to the foundations of our buildings to the crucial urban systems underpinning modern society, UCLA research is increasing our understanding of how the land beneath us moves and how to survive a major quake.

It’s estimated that up to 3,000 people died in San Francisco in 1906 as a result of the 7.9 magnitude quake, and more than 140,000 died in the 1923 Great Kanto earthquake in Japan. Fortunately, in more recent years, particularly in the United States, earthquake-caused deaths have been relatively rare. Unlike in the past, when buildings crumbled and crushed the people inside, we now know how to construct buildings that can withstand quakes.

We learned from buildings that fell. In 1994, a 6.7 magnitude earthquake that struck in the San Fernando Valley destroyed or significantly damaged an estimated 90,000 buildings. Of the approximately 60 people killed, 33 were in buildings that fell. The most common were small apartment buildings perched over space left largely empty for parking. With enough shaking, the apartments come crashing down on the mostly hollow space below.

Scott Brandenberg, a professor of civil and environmental engineering at the UCLA Henry Samueli School of Engineering and Applied Science, studies the impact of earthquakes on the built environment. He lives in a soft story building.“It’s hard to find buildings in the area I can afford,” he says. Soft story buildings were not designed to resist earthquake forces specified in the current building code and should be evaluated for retrofit. A number of these buildings collapsed during the 1994 Northridge earthquake.

Today, Brandenberg’s building, as well as thousands of others across the region, have been retrofitted through mandatory retrofit ordinances.

Learning from the past is key to UCLA’s earthquake research across multiple fields. Brandenberg, for example, is creating an international database on liquefaction, the phenomenon sometimes observed during earthquakes in which soil flows like a liquid, causing land to slide and foundations of buildings to slip away. He and his colleagues are collecting case studies globally that shed light on the consequences of liquefaction. “We’ve never really had a database that was available to the whole community,” says Brandenberg. He hopes broad access to the data will help standardize the science behind liquefaction.

Researchers can’t wait around for earthquakes to strike; the stakes are too high. Jonathan Stewart, a professor in the Department of Civil and Environmental Engineering, has been collecting global data on earthquake impacts on levees and their associated drinking water systems. His major area: a 1,100-mile network of levees in California that directs water into the State Water Project’s drinking and agricultural water conveyances and prevents salt water intrusion from the San Francisco Bay.

“A good 40 percent of the water in Southern California is coming through this system,” he says. “So the stability and viability of this system is really a big deal. For the system to work, the whole thing has to work. You can’t just analyze individual sections. So we’ve developed methods to do that.”

Based on previous seismic activity near levee systems in places like Japan, Stewart and his colleagues can determine the dynamic properties of the peat that makes up much of the structure of the foundation beneath the levees in the Delta, learning how much levees can settle, which can lead to overtopping and cause erosion. They also determine how much soil to keep in reserve to patch breaches that occur. Add in computer modeling, and they can predict worst-case scenarios for disruptions to the system and plan how to respond.

This type of systemic, model-based thinking is new for earthquake research, a field that has been largely based on observations of specific events. “[Research] was being done on a small-time basis: individual faculty and their grad students working on something, producing a paper, other people doing the same thing, and we get all these disparate documents out there,” Stewart explains. “And then somebody has to figure out what to do with it all. We’re trying to change the paradigm by which this research is done.”

Practitioners outside the university who are applying this information to the real world say UCLA’s work is making a difference. Ronald T. Eguchi is president and CEO of Long Beach-based ImageCat, which creates earthquake maps and hazard exposure models for buildings and infrastructure. The company serves clients like NASA and FEMA, as well as private insurance companies. Eguchi says the data coming out of UCLA has helped make these maps more accurate.

“Without [that UCLA] research, I don’t think we’d be able to come up with these quantitative assessments,” he says. “We use that information to [learn] what the extent of displacement or ground failure would be.”

Useful data can come from surprising sources. Engineering Professor Ertugrul Taciroglu, who studies earthquake effects on urban infrastructure — ports, bridges, power lines — has developed a way to use the abundant images available from Google to visually analyze infrastructures and develop predictive simulation models to quantify their seismic risks.

“My students and I developed computer codes that will locate each bridge and examine it through Google Street from multiple angles. Our algorithms extract key measurements, such as column heights and cross-sectional dimension. We use those measurements to create a structural analysis model. We intend to do that for all 25,000 bridges in California,” he says. These images are remarkably accurate. Taciroglu says he has checked his models using Google’s images against Caltrans’ original bridge blueprints, and the measurements match up at the sub-inch level.

Google Earth also has been a rich source of data for power lines and other lifeline transmission corridors that provide electricity across the state. “I can create structural analysis models of power distribution networks by going around with my preprogrammed robot inside Google Earth and extracting where the transmission towers are, the length of the cables, the sag of the cables,” Taciroglu adds. “Because I know where they are, I know what kind of an earthquake shaking we can expect in the future for each structure.”

Knowing how transmission lines may fail in a big earthquake can show, for example, what hospitals should be better equipped with backup power. Modeling which bridges could fail will help us understand how to prevent parts of cities from being cut off from essential services. Taciroglu says a dream project would be to integrate all this information into one massive model that encompasses the full complexity of an entire urban region and all its interrelated risks. Such a tool would be immensely valuable to government agencies, facility operators and insurance agencies.

This kind of metropolitan-wide thinking may not be far off. A task force of UCLA earthquake researchers is developing plans to better integrate systems thinking and earthquake consciousness into the operations of city and county entities, such as utilities. “Lifeline infrastructure can be impacted by big earthquakes,” says Ken Hudnut, a geophysicist for Risk Reduction at the U.S. Geological Survey and a lecturer in UCLA’s Department of Civil and Environmental Engineering, who advises the L.A. Mayor’s Office of Resilience.

Continue reading at UCLA Magazine

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