Laptops as Earthquake Sensors

Earthquake researchers in California hope to take advantage of the motion sensors in laptops to create an earthquake-sensing network. By putting computers in homes and businesses to work as seismic monitors, the researchers hope to pull together a wealth of information on major quakes, and perhaps even offer early warnings, giving a few seconds' notice of a potentially devastating quake.

The Quake Catcher Network (QCN) is in the beta testing stage, with links to several hundred laptops. It's a distributed computing network, like SETI@home, which searches for intelligent signals from space, and Folding@Home, which focuses on protein folding. Machines in the earthquake network would monitor motion and report big shakes to a central server. If a horde of reports came in from a particular area, it could indicate an earthquake. The network will initially focus on the quake-prone San Francisco Bay and the Greater Los Angeles Basin areas of California.

"Were not trying to predict earthquakes, we're trying to measure them very rapidly and get the information out before damage is done to large populations," says Jesse Lawrence, an earthquake seismologist at Stanford University. He's working on the project with Elizabeth Cochran, an assistant professor of seismology at the University of California, Riverside, who came up with the idea, and other collaborators at both universities.

Hundreds of sophisticated seismometers are already in place in California, but they're spaced relatively far apart. The new distributed network wouldn't replace those, says Paul Davis, a professor of geology at the University of California, Los Angeles, but "it would fill in the gaps."

The QCN team has developed software that turns Mac laptops into seismic sensors and displays seismic data on a screensaver. They plan to later release a Windows version. Apple laptops manufactured since 2005 are outfitted with accelerometers, as are many IBM (now Lenovo such as ThinkPad T40, ThinkPad T41, ThinkPad T42, ThinkPad T43, ThinkPad R50, ThinkPad R51, IBM FRU 08K8193, IBM 92P1060, IBM 08K8214, IBM 08K8195, IBM 08K8193, IBM 08K8192 and IBM 92P1101), Acer, and HP laptops. They detect sudden acceleration--as when a laptop falls from a table, for instance--and brace the hard drive for impact.

Desktop computers don't have built-in accelerometers, but they can easily be outfitted with inexpensive USB shake sensors, Lawrence says, which are already used in the automotive industry to develop and test safety devices such as airbags. Lawrence and his collaborators hope to distribute USB shake sensors to schools so students can be part of the network.

The Quake Catcher Network's software will analyze shakes sensed by a computer's accelerometer and report only big movements to the central server, ignoring the vibrations from a passing truck, a bump to a table, or even a minor earthquake. The pattern of signals received by the server should allow the network to recognize a significant earthquake, Lawrence says. The location of networked computers will be identified by their IP addresses and from reports from users.

Some scientists, including Egill Hauksson, a senior research associate in geophysics at Caltech, who oversees the Southern California Seismic Network, have doubts about the quality of that data. Nonetheless, Hauksson says, "If you have hundreds of thousands of these computers reporting, maybe you will see something interesting."

Sensors in quake-prone areas such as California are miles apart, and Davis says if there were more QCN-linked computers in an area, they could provide information on how the shaking varied across the affected area. "It's obviously a very limited seismometer," Davis says, "but it would indicate where the biggest shaking concentrated in a way we've never done before."

The devastating Northridge earthquake, which hit Los Angeles in 1994, had some unexpected effects in parts of Southern California, Davis says, so scientists deployed seismographs in backyards to try to figure out what was going on. "Had there been all those laptops measuring at the time, that could have been worked out much quicker," he says.

Lawrence's hope is that the network might even be able to give an early warning of quakes, based on the relatively gentle waves that occur before the more brutal ones. Even just a few seconds of warning may be enough time for people to take cover and automated systems could slow trains and divert traffic from vulnerable bridges. There's no such system in the United States, but in Japan, high-speed trains are stopped when a major earthquake is detected.

However, Caltech's Hauksson says he's "very skeptical about using this kind of network for warning."

Although David Oppenheimer, a seismologist with the U.S. Geological Survey, who isn't involved with the project, sees "significant problems" with the notion of using laptops as quake sensors, he's intrigued by the idea of equipping desktop computers with inexpensive seismic sensors.

"To me, that's very exciting because there are large portions of the world where we don't have adequate seismic monitoring," Oppenheimer says. If USB accelerometers were attached to internet-connected computers in those regions, they could detect a quake more quickly than more-conventional sensors located hundreds or thousands of miles away.

If something like the QCN had been in place in Indonesia in 2004, when a huge quake triggered a devastating tsunami, it could have helped in warning emergency workers. "Thousands of kilometers of laptops could have lit up in Sumatra," Davis says. "They could know within a couple of minutes that it happened," rather than waiting for the half-hour it took for the quake to be picked up on sensors farther away. That earlier notice could allow response teams to mobilize more quickly during the next quake, and tsunami warnings could be issued in time to make a difference.