Coming to your computer — a crowd-sourcing approach to earthquake detection (VIDEO)
It’s 3:32 on a Tuesday afternoon. You’re in the office, staring at your computer but pining for a coffee break. The screen starts to shiver, the desk rumbles and the shaking under your feet sends ripples of recognition up to your brain: It’s an earthquake.
What’s the first thing you do?
You look around to see who else felt it and to assess the danger. Some water spilled, but nothing is falling. The worst is over. Bob opens a Google search for “earthquake.” Linda goes straight to the U.S. Geological Survey’s website, but the page is taking awhile to load. You turn back to your computer and pull up some geological data of your own. “Magnitude 4.4, probably didn’t cause much damage,” you tell the group.
Your computer is connected to the Quake-Catcher Network, a research initiative run out of Stanford University that aims to evaluate seismic shaking as it happens. Unlike the USGS, which uses a smaller number of very expensive, very sensitive seismographs to measure ground movement, the Quake-Catcher Network has thousands of volunteers collecting seismic data through their personal computers.
The researchers developed a sort of mini seismograph that plugs into members’ computers with a USB cable. Many newer-model laptops don’t even need that hardware — the network can tap into their internal accelerometers, originally designed to shut the computer off if gets dropped.
The idea behind the Quake-Catcher Network is to reduce the time it takes for seismic waves to reach the nearest sensor. With more sensors, in more places, a big quake might be detected right when it begins.
When a fault ruptures, it sends out two types of shock waves. Those that travel along the surface, called p-waves, are faster but weaker. S-waves, which radiate through the ground, take longer to arrive but can pack a huge punch.
The size of a quake can be determined based on the first 4 seconds of p-wave, said James Dolan of the Southern California Earthquake Center. “If you can figure out if it’s a big one right away, in the first seconds of the rupture, that’s where you can make a big difference,” he said.
An early warning system would use that p-wave analysis as a trigger to stop trains in their tracks, shut down power plants and send out public alerts in the crucial seconds before the stronger s-waves arrive.
Last March, Japan’s early warning system was activated within 9 seconds of the magnitude-9 quake that set off a devastating tsunami. Residents in Tokyo, 230 miles from the epicenter, had about 80 seconds to prepare for the jolt.
Japan’s warning system cost over a billion dollars and took nearly 20 years to build. The Quake-Catcher Network aspires to a much cheaper model. “Because the sensors we’re using are so cheap, we can pepper the world with them,” said Project Manager Jesse Lawrence. That includes places like Haiti, Turkey and Mexico City, where poor construction increases the earthquake fatality rate. (Geologists have a saying: “Earthquakes don’t kill people, buildings do.”) Survival rates might increase if people have time to duck and cover, or run out of a shoddy building and into an open field.
Lawrence, a geology professor at Stanford, said it will probably take a few more years before the network can be proved effective enough to aid in public safety. The only way to test the system, he said, is to wait for a large earthquake and see how it performs.
When a small quake hit near El Cerrito in March, “we were able to detect it in 8 or 9 seconds,” Lawrence said. “That was well before the stronger waves” travelled 35 miles south to the larger seismograph at Stanford.
To date, Lawrence’s network has about 2,000 volunteer participants worldwide, and aims to triple that number in the next two years. Anyone who lives in a quake-prone region can request a sensor for free, and others can buy one for $49.
Participants like Bob can watch the seismic waves rippling under their home or office, and even set the waveforms as their screensaver. Someday, the network might be able to provide a pop-up alert: Earthquake, M7.0. Shaking estimated in 20 seconds. Take cover. It’s not all the time in the world, but it could replace that moment of indecision, that split second when you wonder if this is just another one, or the Big One.