The technology could serve regions of the world that cannot afford higher quality, more expensive, conventional earthquake early warning systems, or could contribute to those systems, researchers said.
    
The study, led by scientists at the US Geological Survey (USGS), found that the sensors in smartphones and similar devices could be used to build earthquake warning systems.
    
Despite being less accurate than scientific-grade equipment, Global Positioning System (GPS) receivers in a smartphone can detect the permanent ground movement (displacement) caused by fault motion in a large earthquake.     Using crowdsourced observations from participating users' smartphones, earthquakes could be detected and analysed and customised earthquake warnings could be transmitted to users.
    
"Crowdsourced alerting means that the community will benefit by data generated from the community," said Sarah Minson, USGS geophysicist and lead author of the study.
    
Earthquake early warning (EEW) systems detect the start of an earthquake and rapidly transmit warnings to people and automated systems before they experience shaking.
    
While much of the world's population is susceptible to damaging earthquakes, EEW systems are currently operating in only a few regions of the world, including Japan and Mexico.
    
Researchers tested the feasibility of crowdsourced 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 show that crowdsourced 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 5,000 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, 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.
    
Comprehensive EEW requires a dense network of scientific instruments. Scientific-grade EEW, such as the US Geological Survey's ShakeAlert system that is currently being implemented on the west coast of the US, will be able to help minimise the impact of earthquakes over a wide range of magnitudes.