Web surfer, music player, email reader... Add one more potential function to your smartphone: earthquake detector.
Researchers say that crowdsourcing data from the navigation tools built into most smartphones could provide a lifesaving early warning when an earthquake strikes.
Quake-prone regions of Japan, the United States and other countries have large networks of precision sensors that detect ground movements during a tremor.
The equipment is expensive, however.
“There are a lot of parts of the world that don’t necessarily have the resources to afford a scientific-grade network,” U.S. Geological Survey geophysicist Ben Brooks said.
But a growing number of people worldwide carry smartphones — advanced models of mobile telephones — equipped with GPS navigation and devices called accelerometers, which measure changes in speed and direction. Smartphones use them to tell which way is up, among other things.
The phone’s instruments are not as accurate as those scientists use, but Brooks says when his group compared them to research-grade sensors, they were surprised by how good they were.
And what they lack in accuracy, they make up for in numbers.
“If you have hundreds and hundreds of measurements, maybe each one won’t be that accurate,” said Ohio State University geophysicist Michael Bevis, who was not involved with the research. “But the [average] signal that comes out of those hundred people in this one area is probably reliable.”
And crowdsourcing also would verify that an earthquake really was happening. One shaking phone would not set off alarms; that could just be someone jumping on a bus.
“But if the entire population were jumping at one time, it would be very improbable that it would be anything aside from an earthquake,” Brooks said.
In a simulated magnitude-7 earthquake near San Francisco, Brooks and colleagues found that with less than 5,000 phones feeding into the network, they could detect the quake 5 seconds after it started.
That would provide enough time to warn people to take cover before the most damaging waves from the tremor arrived.
An alarm system could automatically take safety steps such as switching off gas lines to prevent fires.
The research appears in the journal Science Advances.
Other earthquake researchers are also tapping into tools that are increasingly common in our computer-driven world. Many laptops use accelerometers to shut off the hard drive when the computer is dropped. The Quake-Catcher Network gathers accelerometer data from volunteers’ laptops, phones and other devices, mostly in the United States and Europe.
It’s important to note, however, that Brooks’ group did not get their results with off-the-shelf cellphones.
He explains that today’s smartphones process their GPS and accelerometer data in a way that can be useful for a person walking down the street looking for a restaurant, but less so for detecting earthquakes. The researchers had to undo some of the data processing the phones do routinely to compensate for the jiggling that happens as you walk.
A software change could fix that, if phone makers wanted to. And, Brooks says, he expects phones will soon have even more precise GPS systems to enable detection of subtle movements.
Still, he says, today’s phones are able to accurately detect the strongest earthquakes - mammoth jolts of magnitude 8 or higher.
Assuming the cellphone network survives long enough.
Bevis was in Chile in 2010 following a devastating magnitude 8.8 earthquake. “The first thing that collapsed was the cellphone system,” he said.
But, he says, using crowdsourced smartphones is a good idea, especially in places with no existing seismological infrastructure.
