The system works on Android phones, essentially any phone that isn't an iPhone. Android phones, which are often more affordable, make up about 80% of the phones in Turkey.

"If Google makes a promise, or makes an implicit promise, to deliver a service like earthquake early warning, then to me, it raises the stakes," says Prof Harold Tobin, director of the Pacific Northwest Seismic Network.

"They have a responsibility to be able to follow through on something that is directly related to life and limb."

Google's product lead on the system, Micah Berman, insisted it had worked. "We are confident that this system fired and sent alerts," he told the BBC.

However, the company did not provide evidence that these alerts were widely received.

More than 50,000 people died in February's earthquake.