[Fatnino]

Notifications are rare because you need to be far enough from the epicenter that the difference between the speed of the earthquake (speed of sound in rock) and the speed of the notification (speed of light through the internet) is great enough to matter. But at the same time you can't be too far from the epicenter or the shaking where you are will be negligible and the alert pointless. Most earthquakes are too small to have a significant ring around them where notification makes sense.