Almost all smartphones contain accelerometers that can detect and record movement. Researchers at the Berkeley Seismic Laboratory in California say they are capable of monitoring tremors.
An app to record the shaking during major earthquakes and then report the data back to a central server over the wireless carrier's network is under development, they say.
With tens of millions of smartphones in use, researchers said, they could obtain very detailed information on how strong tremors were and where they were centered.
"Nowadays, smartphones carry all sorts of sensors, and we can put these to use in unexpected ways," researcher Qingkai Kong told BBC News. "Right now, we can only detect earthquakes above about magnitude-5, but with better accelerometers in future smartphones we would hope to detect smaller ones as well."
To see if mobile phones could be used as pocket seismometers, a number of the devices were put on the seismic lab's "shake table," which can simulate tremors of various strengths.
The researchers found the phone accelerometers -- primarily used to re-orient the screen display when the phones are tilted -- could pick up the shaking.
Of course, smartphone aren't generally sitting on a flat table but are moving with their owners, so the researchers say they've developed an algorithm that removes the movement "noise" from the phones' data.