Early earthquake warnings? There's an app for that
For many of us, smartphones have become the primary tool for organizing our lives. Scientists at the U.S. Geological Survey are working to turn them into tools for not just organizing but saving lives.
Specifically, USGS geophysicists are developing earthquake early-warning systems that can grab data from smartphones and pass along alerts to those in the path of earthquake shockwaves.
According to USGS geophysicist Sarah Minson, the idea for smartphone crowdsourcing came out of the service's work on the ShakeAlert early-warning system that is being deployed on the West Coast using seismic instruments.
"It was really pretty spontaneous," she said. One team member suggested using consumer GPS to supplement the data from USGS's scientific instruments. "People hadn't looked really looked at consumer GPS before, probably because the accuracy in terms of your location of GPS in your phone is really quite terrible. But its ability to sense your change in position from point A to point B is really quite good."
In fact, the team determined that the GPS available in smartphones is capable of detecting earthquakes with a magnitude of 7 or greater. Using specific software, a smartphone can transmit an earthquake’s detected location and magnitude to the USGS, which can then send alerts to others in the path of the shock waves.
"You can transmit information at the speed of light," Minson explained. "The damaging secondary waves – S waves – travel about 3.5 kilometers per second. That's fast but not as fast as the speed of light."
While the warning may reach people only seconds in advance of the earthquake, those seconds can be critical. "If you get a warning you can get under your desk and hold on," she said. "A few seconds is also long enough to do stop doing something you don't want to be doing during an earthquake, such as a doctor operating on a patient."
While Minson's team has proved the viability of using smartphones in an early-warning system – and published the results of their study in the April 10 edition of the new AAAS journal Science Advances – there are currently some practical limitations. First, of course, is that earthquakes with a magnitude of less than 7 can't be accurately detected using the current accuracy of GPS in consumer smartphones.
As a result, Minson said, "in the United States, the system would be at most a supplement, augmenting the early warning system that we are building with scientific instruments." But she notes that many areas of the world have no early-warning system at all, so even the limited sensitivity of smartphones can provide a critical advantage.
Another hurdle is that consumer smartphones currently don't allow direct access to GPS data. "The hardware in the phone is great, but the OS usually doesn't let you actually access that data," Minson said. Accordingly, smartphone manufacturers will have to cooperate before volunteers’ smartphones could be looped into a crowdsourced early-warning system.
In the meantime, the USGS team just received funding from U.S. Agency for International Development for a one-year project to develop a smartphone-based earthquake early-warning system in Chile. According to Minson, this project will not be using crowdsourced data. "These will be phones that we own and dedicate full-time to early warning," she said. "But it will give us an opportunity go through the exercise, providing the software for the phone, pulling acceleration data off the phone, pulling GPS data off the phone and bring the data back for analysis."
Posted by Patrick Marshall on Apr 21, 2015 at 2:07 PM