I heard that Twitter and the National Seismological Network have jointly launched an APP that can push earthquake news. I don't know what the principle is!

You are talking about the earthquake quick report APP. Actually, the reason is very simple. When an earthquake happens, mobile phones in the same area will vibrate at the same frequency. You can basically conclude that the earthquake happened, and the earthquake came first by longitudinal waves. If push is used to push information to users around the earthquake as quickly as possible, earthquake early warning can be realized, so that users can be informed before the arrival of destructive shear waves. When an earthquake occurs, the earthquake quick report will push a message to the users in the corresponding associated area according to the magnitude, and the users in the earthquake area will receive the earthquake message reminder at the first time, and users in other areas will not be disturbed by this message, thus winning tens of seconds of precious escape time.