By Erik Sofge
Spectators look at a Pomona, California, scene where bricks collapsed into an alley from an unoccupied building during a magnitude 5.4 earthquake on July 29th. (Photograph by David McNew/Getty Images)
Yesterday morning, Los Angeles dodged another bullet. The earthquake that originated near Chino Hills, roughly 35 miles east of downtown L.A., was powerful enough to rattle homes and damage a hotel near the epicenter. But with a magnitude of 5.4, it was classified by the United States Geological Survey (USGS) as a moderate quake—one of 39 such events in the country this year. A moderate earthquake could pose a serious threat in some regions, particularly in places like New York City, where many brownstones were built more than a century ago. In Southern California, where seismic upheaval is practically routine, this quake left few signs of its passage.
“Engineered structures are meant to withstand a 5.4 earthquake,” says Jamie Steidl, a research seismologist at the University of California at Santa Barbara’s Institute for Crustal Studies. “Even non-engineered, old, unreinforced masonry structures should still be okay. There’s lots of old stuff in Long Beach, and in some of these cities that have been around awhile—older brick buildings that aren’t reinforced. But at this magnitude, we’re not even pushing what the building code was 80 years ago.” The quake preparedness of Los Angeles was put to the test yesterday, but only barely.
The Chino Hills event, minor as it may have been, was a reminder of the United States’ earthquake vulnerability. In Japan and Mexico, researchers have developed earthquake early warning systems, which can detect seismic activity and trigger a sequence of automated responses. This is a frantic sort of race, since the waves created by an earthquake propagate at some 3 kilometers, or nearly 2 miles, per second. In Japan, where quakes tend to start in offshore subduction zones, some areas would have a minute or more to prepare for the worst. “There’s a whole bunch you can do in 60 seconds,” says Thomas Jordan, director of the Southern California Earthquake Center (SCEC). “Shutting off gas mains. Conditioning the electrical grid for what’s going to happen. In hospital situations, especially during surgery, there’s a lot you can do.”
So far, Japan’s early warning system hasn’t done very much—it failed to detect the country’s last two moderate quakes. But in the United States, the outlook is even worse, since no such earthquake early warning system exists, though some preliminary research is underway. “Right now, we’re just fiddling with the concepts,” says Jordan. “We’re not into operational testing, yet.” Coincidentally, says Jordan, a Caltech team reported that its experimental detection gear had been off-line when the Chino Hills earthquake hit.
Realistically, however, if the recent quake had been severe, closer to the 6.7 magnitude that the USGS says is almost certain to hit the state in the next few decades, an earthquake early warning system wouldn’t have helped. The quake simply occurred too close to Los Angeles, with the ground-shaking waves hitting the city in less than 20 seconds. That’s why most of the research into early warning is focused on the San Andreas fault, which can produce earthquakes as close as 40 km (25 miles) from L.A., or as far as 200 km (nearly 125 miles) south of the city. With enough distance, a system-wide alert becomes viable. “Think of an earthquake as a cascade of events,” Jordan says. “They can generate tsunamis, which take some time to hit. Fire following earthquakes, that’s one of the biggest problems you can have. So you get the firetrucks ready, the station doors open. If you know what is happening, you can begin to prepare for what is going to happen later in that cascade.”
As limited as an earthquake early warning detection might be, the potential benefits—particularly in Southern California—seem clear. “It’s something we should be pushing a lot harder than we’re pushing. And we’ve fallen behind other countries. We’ve been a little remiss, to be honest,” Jordan says. He believes a system could be up and running in California in five years, at the earliest. That’s assuming that government agencies like the National Science Foundation and the USGS greenlight additional funding for research. Unfortunately, Jordan thinks it could take a large disaster to make that happen.
In the meantime, the SCEC is helping to prepare for just such a disaster, with the United States’ largest earthquake drill. Scheduled for this November, the Great Southern California Shakeout will test the region’s response to a simulated 7.8 magnitude quake at the southern end of the San Andreas fault. Using supercomputers, seismologists have created a scenario that calculates where the most severe damage would occur, how many fires might be started, and how many lives could be lost. The event will include at least 5 million participants throughout the region, from schools and firefighters to agencies like FEMA. “In a recent meeting, the L.A. County Fire Chief told us, ‘We’ve never really thought this through,’” Jordan says. “A lot of the standard operation procedures wouldn’t apply. That’s what we learned from Katrina. A big enough hammer blow shatters the system. We want to make sure that when that hammer comes down this time, and it’s going to come, the system doesn’t break.”