Rescue workers in China’s Sichuan province searched for survivors on Tuesday as researchers the world over continue to hunt for solutions. (Photograph by AFP via Getty Images)
When southeastern China was struck by a magnitude 7.9 earthquake two days ago, it was the latest in a string of disasters offered the world over by Mother Nature. Now it has unraveled into a full-blown crisis. The official death toll has passed 12,000, but experts believe it will climb beyond 18,000. A number of factors are contributing to the fatalities, such as blocked roadways and a series of at least 30 aftershocks in Sichuan province. The quake itself is no surprise—the region is well-known for its seismic activity—but the persistent threat of earthquakes and, despite decades of research, the lack of warning technology, is alarming. So what can scientists, engineers and lawmakers do to prepare for the next shockwave?
Decades to Impact /// ForecastingCan a network of GPS sensors store enough data online to scout the Bay Area's looming quake? And could the rig work in the Chinese countryside?
Geologists who specialize in earthquakes have become expert gamblers. By analyzing seismic data from sensors and historical records of past events, researchers attempt to calculate the odds in a given region within a specific timeframe. But that timeframe is generally measured in decades—or even centuries. For example, it's estimated that, on average, San Francisco's Hayward fault generates an earthquake every 140 years—and we just passed the 140-year mark. "That would basically be our equivalent of the Kobe earthquake that hit Japan in '95," says Michael Blanpied, associate coordinator of the Earthquake Hazards Program at the United States Geological Survey (USGS). "That led to 5000 deaths." So while a major quake in San Francisco is no certainty this year, or even in the next decade, the odds are getting worse, and the danger harder to ignore.
In Sichuan province, the danger was clear. A magnitude 7.5 earthquake hit the region in 1933, killing more than 9000 people, and geologists have detected smaller events with relative frequency. "We estimated the seismic hazard and risk for that region," says Kaye Shedlock, who worked with China when she headed the USGS's hazard and risk program. "It's riddled with large faults, to accommodate that sort of motion. It moves more often than our San Andreas fault." Compared to some areas that might expect an interval of a century or more between major earthquakes, then, the Sichuan Basin is an extremely active spot. Unfortunately, it also appears to lack the level of monitoring required for accurate forecasting. "In the sliding scale of where you put your resources," Shedlock says, "that's an area where it's difficult to monitor—difficult to get to, because of the mountains—and it's less populated than other vulnerable cities, like Beijing."
The key to forecasting is data, which means a comprehensive, unified monitoring system, which is what Shedlock is trying to provide for North America. She's the program director for EarthScope, a National Science Foundation–funded effort to install thousands of sensors throughout the continent. The instruments range from portable seismometers to clusters of stationary GPS receivers deployed along known fault lines. With all of EarthScope's data freely available online, Shedlock hopes to improve our understanding of the continent's seismic activity—and improve the state of the art of forecasting. More sensors and better analysis could narrow the window for specific threats, and provide more accurate damage estimates and long-term warnings. Ultimately, more data can only be gathered by a larger, more sophisticated network of sensors. Most of the sensors in the U.S. are currently gathered in the western part of the country, while Shedlock expects China to eventually develop its own unified system. But for now, population density remains paramount there, which means Beijing is heavily monitored, while rural areas, such as Sichuan province, remain in the dark.
Seconds to Impact /// DetectionAs China staggers, will Japan's new motion monitors set the world on the path to quake prediction? And can the U.S. get its early warning system up and running fast enough?
Last October, Japan rolled out the world's first national early warning system for earthquakes. Less sophisticated systems of the past included motion sensors that, in the event of strong movement, would cause bullet trains to brake. Now the system is designed to detect an earthquake—and quickly project the level of shaking in surrounding provinces. Alarms will sound, air traffic controllers will be alerted, and lives, potentially, will be saved. But when the warning comes, the threat won't be far behind. Seismic waves travel at an average of 6 kilometers (about 3.7 miles) per second, covering hundreds of miles in a single minute. That's enough time to warn students to duck under their desks, and possibly enough time to clear a bridge or stop a train. But it isn't enough time to evacuate a building. If China had the resources for an early warning system similar to Japan's—even one exponentially larger—it likely would not have helped the 900 students trapped in a collapsed school in Sichuan province, or the thousands buried in buildings throughout the region. To save them, researchers would need to be able to predict an earthquake minutes or hours before the shockwave hit.
"Earthquake prediction is one of the holy grails of science," Shedlock says. "The Chinese worked much harder at this than us, and appeared to have early successes. Then another earthquake happened that didn't behave like the previous one." In the course of evaluating and authorizing earthquake research, the USGS has spent decades following attempts to predict quakes. "The research being done spans the spectrum—from serious, scholarly, scientific research, to pure speculation," says Blanpied. For example, when geologists have created small earthquakes in the lab, they've noticed an acceleration of the sliding along the fault, just before the quake hits. But every attempt to detect this acceleration has failed to produce solid predictive data. Despite a long-running experiment in Parkfield, Calif., which included highly sensitive instrumentation, the only evidence of the magnitude 6 earthquake that finally hit in 2004 was the earthquake itself.
So while prediction remains something of a scientific dead end, the USGS is working with researchers in California to develop an early warning system similar to Japan's. The three-year study will wrap up next year, but the results already appear promising. The University of California at Berkeley's ElarmS system, which uses data from the state's existing seismic network, is currently in the pre-prototype stage. However, Blanpied says that when ElarmS was tested on a magnitude 5 quake, it could have determined shaking some 15 seconds before it started. The precise amount of advance notice depends on a site's relation to the epicenter, but considering the distance between Los Angeles and the San Andreas fault, a similar system could provide the city with what Blanpied calls "a fair amount of warning time." Early earthquake warning in the U.S. would require upgrades to the existing monitoring system, as well as increased manpower, but it's feasible. In China, though, it's a distant prospect.
Last Resort /// EngineeringHow can next-generation materials science help quakeproof American infrastructure? And does rural China have a low-tech option?
Whether you can forecast an earthquake decades before it hits or warn the public seconds in advance, there's no way to stop it from happening. So the best way to prepare for an earthquake is to prepare your infrastructure. Researchers are developing materials, such as flexible concrete that will bend before it breaks, that can absorb the energy of sudden shaking. For critical infrastructure, such as bridges and dams, a more malleable concrete could save lives and money, but the research and the materials can be costly. Other research involves isolating the energy from the ground movement, creating a kind of shock absorber for a home, or allowing towering retail shelves (think Home Depot) to rattle without tipping over. In some cases, a lower-tech fix can provide significant resistance. Placing strips of nearly tearproof fabric between the layers of an adobe structure could essentially tie a building together. Even a traditional wood-frame house or building might stand up to shaking better than a concrete one. In other words, if your infrastructure is built using the right materials, there's a better chance it will survive an earthquake. Or at the very least, it may not land on your head.
But when it comes to nonreinforced masonry buildings, that's exactly what happens. From three-story brownstones to mid-size concrete office buildings, many of the structures in the U.S. that were built from the beginning to the middle of the last century are extremely vulnerable to earthquakes. Building codes vary from state to state (and country to country, for that matter), but as Blanpied points out, "If a magnitude 5 hit near Manhattan, it would be a disaster. Buildings would topple over." Easy as it is to criticize Chinese authorities for not retrofitting or reconstructing the buildings that collapsed in this week's earthquake, the cost of infrastructure rehabilitation is always daunting.
So what could China have done to prepare for a magnitude 7.9 earthquake in a relatively rural region, while still focusing on protecting the millions more in cities like Beijing? More sensors could have allowed for better forecasting, and an early warning system may have saved some lives. But the biggest problem may have been aging infrastructure. More quake-resistant materials, along with responsible building codes, could have at least mitigated the catastrophe. And what's true in China is true in the U.S.—securing our infrastructure requires significant resources, and a groundswell of political will. In other words, preparing for the worst is easily said, and rarely done.