Scientists say some parts of the world are covered in earthquake detection devices, but they are not being used.

A team of geologists in the US say smartphones and other personal electronic devices could, in regions where they are in widespread use, function as early warning systems for large earthquakes.

The average smartphone is equipped with a range of sensors, and if they were made to work together, the combination of thousands of GPS (Global Positioning System) receivers could detect the permanent ground movement (displacement) caused by tectonic fault motion in a large earthquake.

Using crowd-sourced observations from participating users' smartphones, earthquakes could be detected and analysed, and customised earthquake warnings could be transmitted back to users.

Earthquake early warning systems detect the start of an earthquake and rapidly transmit warnings to people and automated systems before they experience shaking at their location.

While much of the world's population is susceptible to damaging earthquakes, EEW systems are currently operating in only a few regions around the globe, such as Japan and Mexico.

Researchers at the U.S. Geological Survey have tested the feasibility of crowd-sourced EEW with a simulation of a hypothetical magnitude 7 earthquake, and with real data from the 2011 magnitude 9 Tohoku-oki, Japan earthquake.

The results showed that crowd-sourced EEW could be achieved with only a tiny percentage of people in a given area contributing information from their smartphones.

For example, if phones from fewer than 5000 people in a large metropolitan area responded, the earthquake could be detected and analysed fast enough to issue a warning to areas farther away before the onset of strong shaking.

“The speed of an electronic warning travels faster than the earthquake shaking does,” said Craig Glennie, a professor at the University of Houston.

The authors found that the sensors in smartphones and similar devices could be used to issue earthquake warnings for earthquakes of approximately magnitude 7 or larger, but not for smaller, yet potentially damaging earthquakes.

But, in the many parts of the world where there are insufficient resources to build and maintain scientific networks, crowd-sourced EEW has significant potential.

The U.S. Agency for International Development has now agreed to fund a pilot project, in collaboration with the Chilean Centro Sismologico Nacional, to test a pilot hybrid earthquake warning system comprising stand-alone smartphone sensors and scientific-grade sensors along the Chilean coast.

“Thirty years ago it took months to assemble a crude picture of the deformations from an earthquake. This new technology promises to provide a near-instantaneous picture with much greater resolution,” said Thomas Heaton, a professor of Engineering Seismology at Caltech.

“Crowd-sourced data are less precise, but for larger earthquakes that cause large shifts in the ground surface, they contain enough information to detect that an earthquake has occurred, information necessary for early warning,” said Susan Owen of NASA's Jet Propulsion Laboratory, Pasadena, California.