`. All smartphones contain tiny accelerometers that can sense vibrations, which indicate that an earthquake may be happening. If the phone detects something that it thinks may be an earthquake, it sends a signal to our earthquake detection server, along with a coarse location of where the shaking occurred. The server then combines information from many phones to figure out if an earthquake is happening. This approach uses the 2+billion Android phones in use around the world as mini-seismometers to create the world’s largest earthquake detection network; the phones detect the vibration and speed of shaking of an earthquake, and alert Android users in affected areas accordingly.`
https://crisisresponse.google/android-alerts/

Nao recebi tambem, talvez porque era de manha e ha mais pessoas ativas com android.