On February 6, 2023, two strong earthquakes occurred in Türkiye - a 7.8-magnitude earthquake in Pazarchik and a 7.5-magnitude earthquake in Erbistan, causing widespread damage across the country. At that time, the Android Earthquake Early Warning System (AEA) was still running. However, for a 7.8-magnitude earthquake, the system estimated a magnitude of 4.5 7.1 seconds after the source time, and the maximum estimated value was only 4.9, which was far lower than the actual magnitude.
This severe underestimation means that only less urgent "BeAware" alerts will be sent to 500,000 devices within a 64km radius, leaving affected people with limited early warning. In the 7.5-magnitude Elbistan earthquake, the initial magnitude was estimated at 6.1 and later rose to 6.3. This resulted in "BeAware" alerts being sent to nearly 4 million mobile phones, with warning durations ranging from a few seconds to more than a minute.
It's important to have a traditional seismic network to catch earthquakes in advance, but many earthquake-prone countries don't have such networks, so a system like AEA is important, even if Google only intends it to be a supplement.
While the system performed regrettably poorly during the Turkish earthquake, the company has realized its flaws and tweaked its detection algorithms. For example, the algorithm's monitoring time for seismic parameters, previously limited to 10 seconds, has been extended to 30 seconds to allow for the collection of more data.
There was a problem in the monitoring pool with late triggering of noisy cellphones, especially during the first earthquake. With the new update, the system can now more accurately select the monitoring range based on the phone's noise level. Google has also updated BeAware alerts so that devices no longer vibrate, allowing them to continue to report earthquake conditions more accurately.
Google has conducted simulation tests using the new algorithm and believes that if a 7.8-magnitude earthquake occurred now, it would detect a 4.6-magnitude earthquake 6.3 seconds later and a 7.4-magnitude 24 seconds later, which would be more accurate than before. As a result, 10 million devices will receive more prominent TakeAction alerts up to 35 seconds earlier, while BeAware alerts will be sent to 67 million users up to 2.5 minutes earlier.
Despite AEA's shortcomings, a survey of more than 1.5 million users who had received alerts in all countries except the United States showed that alerts received an average usefulness score of 4.7 out of 5, with 85% of users saying the alerts were very useful in their specific situation. 36% of users received alerts before the earthquake, 28% received alerts during the earthquake, and 23% received alerts after the earthquake.
Twenty-eight percent of users who received TakeAction alerts followed the "drop," "cover," and "hold on" alerts, a higher rate than previous surveys of other earthquake warning systems. 84% of respondents said they would trust the system more in the future, and only 0.1% had disabled alerts. Hopefully Google's improvements will reduce future fatalities.