BART got a 10 second warning before Sunday’s Napa earthquake. Why didn’t everyone else?

Many historic buildings get damaged in a magnitude-6.0 quake. (Photo by Tayfun Coskun/Anadolu Agency/Getty Images)

At 3:20 a.m. on August 24, an alarm went off at Bay Area transit provider BART’s offices: An earthquake was approaching, and the shaking would start in 10 seconds.

By the time the tremblors reached BART’s tracks in the East Bay and San Francisco, they had become mild enough that no extra safety measures were necessary, BART board of directors member John McPartland said at a press conference Monday. But had the earthquake happened while trains were running at an intensity of a 3.1 earthquake or higher, the warning would have prompted trains traveling at 30 MPH or less to stop, and trains moving faster to slow.

It all would have happened automatically based on 12 earthquake sensors installed for BART as a part of ShakeAlert, an early warning system created by the University of California-Berkeley Seismology Laboratory, United States Geological Survey and other partners. Like a tornado or hurricane, it’s possible to predict the approach of an earthquake, and ShakeAlert’s 150 users knew the Napa quake was coming. Berkeley received a 10 second warning. Cities farther south received even longer. The system also predicted that the earthquake would have a magnitude of 5.7–fairly close to the 6.0 magnitude it was officially given.


“This is a great success for us. It’s certainly not the first,” UC-Berkeley Seismology Lab director Richard Allen said at the press conference. The system previously has warned of Los Angeles-area earthquakes.

ShakeAlert detects earthquakes via around 300 sensors scattered across California. They measure what are known as P-waves: non-destructive waves of energy that travel much faster than the S-waves earthquakes produce that cause shaking and damage. ShakeAlert spots P-waves by weeding out vibrations from trucks, machinery and other man-made sources. It determines the origin and size of an earthquake based on the shape of the P-waves.

So earthquake warning systems don’t actually predict an earthquake. They just spot the very first indication that one is happening and alert users before the destructive part begins. Long-range earthquake forecasting is a much more difficult task. Scientists believe San Francisco is long overdue for an earthquake on the scale of the 1906 temblor that led to the burning of 80 percent of the city, for example, but can’t pinpoint exactly when that earthquake will occur.

Animals, it turns out, might be better predictors than us. A 2010 study found that toads seemingly knew about the 2009 L’Aquila earthquake in Italy days in advance, possibly due to changes in electric fields or gases in the air. But unless we begin keeping toads in our homes, we’ll have to make do with the precious few seconds P-waves afford us.

A car is seen covered in bricks following a reported 6.0 earthquake on August 24, 2014 in Napa, California. Justin Sullivan/Getty Images

A car is seen covered in bricks following a reported 6.0 earthquake on August 24, 2014 in Napa, California. Justin Sullivan/Getty Images

So why didn’t every single resident in the Bay Area get that same warning as BART? The answer is funding.

It’s been law since 2013 that California needs to establish a state-wide earthquake early warning system. But the law states that funding won’t come from California’s general fund.

The damage from the Napa earthquake could exceed $1 billion. As many as 200 people were hospitalized with minor and serious injuries, according to the San Jose Mercury News. Interest in earthquake protection is now high, and Allen said there are several potential ways to secure funding. ShakeAlert is close to receiving government money in Sacramento, and people in other parts of the state can contact their legislators to express their support. The best bet is the $7.5 billion water bond that will be voted on in November; it contains funding for an earthquake warning system.

If it does go into effect, a state-wide system could be integrated into more than just transit systems like BART. A self-driving car could automatically stop before entering a tunnel and a factory could shutdown and protect any equipment that contains dangerous materials. Many of the fires that started after the Napa quake were likely caused by broken natural gas lines that could have been shut off by a warning system. Even the Napa Valley wineries, which lost millions of dollars of wine, could have benefitted from some sort of protective measure.

Most importantly, people would have had enough time to move away from heavy or sharp objects, potentially preventing a huge number of the injuries that occurred. Phones, computers, radios and tons of other types of devices could have awoken to deliver the warning to every single Bay Area resident.

“This is a critical need here in earthquake country,” Allen said. “People want this. We just need the necessary investment to complete ShakeAlert.”

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