American researchers are aiming to create a dense smartphone-based earthquake detection network that would improve early warning systems.
Thanks to the three built-in accelerometers designed to sense detection for display or gaming, every smartphone has the capability to detect tremors caused by quakes.
Researchers from the University of California, Berkeley, realised this potential and have developed an app that can differentiate the regular movements caused by walking from those caused by the Earth’s movements.
They are now encouraging the public to download the app, called MyShake, from Google Playstore and become a part of what they hope will become a future worldwide earthquake-sensing network.
The researchers acknowledge that while the technology is not as sensitive as dedicated seismic sensors, the fact that smartphones are so omnipresent in wider society would in many instances make up for the limited sensitivity.
"MyShake cannot replace traditional seismic networks like those run by the US Geological Survey but we think MyShake can make earthquake early warning faster and more accurate in areas that have a traditional seismic network and can provide life-saving early warning in countries that have no seismic network," said Richard Allen, director of the Berkeley Seismological Laboratory and the leader of the MyShake project.
Currently, smartphone-based accelerometers could reliably detect an earthquake of the magnitude five and upwards. Such earthquakes cause damage within a 10km radius from the epicentre. As technology continues improving, so will the sensitivity.
At first, the data from the app will only be sent to the Berkeley team for evaluation. Once the system is proved reliable and enough people are using the app, the researchers hope to start using it to send out alerts to everyone in the potentially affected area.
"We need at least 300 smartphones within a 110-kilometre-by-110-kilometre area in order to have a reasonable estimate of the location, magnitude and origin time of an earthquake," said Qingkai Kong, a UC Berkeley graduate student, who developed the algorithm at the heart of the app. "The denser the network, the earlier you can detect the earthquake."
The app constantly runs in the background, monitoring the phone's accelerometers. It tests every motion to see if it fits the profile of an earthquake. If the algorithm decides that the shaking is from a quake, it briefly activates the GPS receiver to obtain coordinates and immediately sends basic information to the researchers including the time and amplitude of the shakes.
In the lab, cloud-based software constantly reviews all incoming data and, if at least four phones detect an earthquake and this represents more than 60 per cent of all phones within a 10-kilometer radius of the epicentre, the program confirms an earthquake.
The researchers cross-check the information with the California Integrated Seismic Network, which monitors earth movement all over the state using underground seismometers.
With a dense enough network, detection, analysis and warning can take less than a second.
"In my opinion, this is cutting-edge research that will transform seismology," said Kong. "The stations we have for traditional seismology are not that dense, especially in some regions around the world, but using smart phones with low-cost sensors will give us a really good, dense network in the future."
In tests, the algorithm was able to distinguish earthquake tremors from other movements in 93 per cent of cases.