In brief: Google has admitted that its early earthquake alert system failed to inform millions of people about the severity of Turkey’s 2023 quake. The highest level “TakeAction” warnings were only sent to 469 Android users for the 7.8 magnitude event.

On 6 February 2023, a 7.8 magnitude earthquake struck near Gaziantep in southern Turkey, close to the Syrian border. It was followed by a second major quake measuring 7.5 – 7.7 magnitude nine hours later about 59 miles away. More than 55,000 people died, and over 100,000 were injured.

The BBC reports that 10 million people living within 98 miles of the epicenter could have been sent Google’s highest level alert: TakeAction, which gives up to 35 seconds of warning for people to find safety.

The tech giant told the news agency that half a million people were sent a lower-level BeAware warning, which is designed for “light shaking” and does not prominently alert users.

Google’s early warning system was enabled on the day of the quakes – more than 70% of phones in Turkey are Android devices – but it underestimated the severity of the incident.

Google’s Android Earthquake Alerts (AEA) early warning system uses the accelerometer in an Android phone to detect the initial, faster-moving P-wave of an earthquake, at which point it sends a signal to its earthquake detection server along with a rough estimate of where the shaking occurred.

The system analyses data from multiple phones to confirm an earthquake is happening, where it is located, and its magnitude.

The system sends out two types of alerts to warn people before the more damaging S-wave arrives: BeAware for light shaking, and TakeAction for stronger shaking.

The TakeAction alert takes over a phone’s screen and plays a loud sound. Unlike the less severe alert, it overrides any Do Not Disturb setting on a handset.

The first quake in Turkey hit at 4:17 am. Many of those killed or injured were asleep in buildings that collapsed due to tremors. It’s likely that receiving the more severe alert would have woken some of these people.

Google researchers have blamed the AEA failures on “limitations to the detection algorithms.” The system estimated the shaking at between 4.5 and 4.9 instead of 7.8. The second quake was also underestimated, with the system sending TakeAction alerts to 8,158 phones and BeAware alerts to just under four million users.

The researchers altered the algorithm and simulated the first quake again. This time, AEA generated 10 million TakeAction alerts to those at most risk, and sent 67 million BeAware alerts to those living further from the epicenter.

“Every earthquake early warning system grapples with the same challenge – tuning algorithms for large magnitude events,” Google told the BBC.

Scientists have criticized the fact that it took Google two years to release its findings. And while the company said AEA is not a replacement for national systems, many worry that people place too much faith in its technology.