Scientists Want Your MacBook for Earthquake Detection

Seismologist Elizabeth Cochran and a few colleagues hope to add a few seconds to earthquake detection, thereby getting word out faster to a large number of people.
Courtesy Elizabeth Cochran

Everybody knows you can't predict an earthquake. The only way would be to get inside a time machine, go into the future, and send back a message.

So seismologist Elizabeth Cochran of the University of California at Riverside will use thousands of computers to do just that.

Well, it's not exactly a time machine. Cochran and Stanford seismologist Jesse Lawrence have made use of the sensors built into many new laptops that sense when the computer is being dropped, and turned them into earthquake monitors. They hope to sign up thousands of users to act like a grid of detectors that can sense an earthquake before it does too much damage.

Like many earthquake early warning systems around the world, when a quake strikes, this system will send a warning to people living in large cities. Because electronic communication systems (in this case, the internet) are much faster than seismic waves, the warning should arrive before the shaking, giving people 10 or 20 seconds to take shelter.

"We can measure the seismic waves and then get a warning out to people before the seismic waves get to them. That to me is physically possible," Cochran says.

Cochran's system makes use of the accelerometers -- tiny motion sensors -- built into many modern notebooks, including Apple's MacBook and Lenovo's ThinkPad, as well as the iPhone and Nintendo's Wii. Accelerometers detect movement and translate it into digital signals. In notebooks, they function as safety devices: When the accelerometer detects that the notebook is in free fall, the computer moves the hard drive head to a safe position in order to minimize the risk of damage when it hits the ground. But the accelerometers are also accessible to software, so they can be used for games or other applications.

As it turns out, one field that already makes extensive use of accelerometers is seismology. Usually these sensors are buried underground, generating much of the data seismologists use to model earthquakes. So in 2006 when Cochran saw a program called SeisMac, a light went on. SeisMac uses the accelerometers in Mac computers to let people shake their computers and watch the motion translated on screen into a graph. Cochran wondered if the same technology could be used in earthquake sensing, and suggested the idea to colleagues at the Scripps Institute of Oceanography, where she was working at the time.

"I sort of said, 'Hey, what do guys think if we take this accelerometer and make a seismic network out of it?' And of course Jesse was like, 'That's the coolest idea I have ever heard.'"

Thus was born Quake Catcher Network. The two scientists -- joined by Carl Christensen, a programmer with experience in distributed computing -- started in September 2007.

Distributed computing was made famous by extraterrestrial-scanning network SETI@home, and Cochran uses the same platform, called BOINC, to collect data from the laptops in her project's network.

However, it may be awhile before the Quake Catcher is up and running. For one thing, it is extremely hard to decide if a set of movements is an earthquake or, say, just someone working next to a jackhammer.

To sort through the bogus data, the team has to set up algorithms that weigh the statistical probability that half a dozen computers would be shaking the same amount at the same time. They are still working out how to do this, but Cochran estimates perhaps 10 hits or so may be enough to certify that an earthquake is happening.

However, this is where Quake Catcher breaks new ground. Not all "stations" will likely be the same. Some data will inevitably be ranked better than others. For instance, if you nervously jiggle your leg while you work, your laptop's earthquake detection data will be looked upon with suspicion. Cochran and Lawrence expect that once the network is up and running, users will be able to check their ranking based on how much they shake their desks.

It's not the first time laptop accelerometers have been used for earthquake measurement. The San Diego Supercomputer Center also links laptop volunteers with webcams to give researchers around the world another tool to understand earthquakes after they happen.

As for Quake Catcher, it's months from even limited release and probably years from issuing warnings. The system is far from perfect. It relies on massive numbers of volunteers that have to stay online. And it's hard to tune it without large earthquakes. So until then, the team is hoping people sign up, leave their laptops on, and then just hold still.

"The ideal situation is that they start up BOINC and they leave their laptop in their closet until the earthquake happens," she says, laughing. "That would be great for us."