Countdown from a time read from database

Dear all,
We are working on an early warning system for earthquakes. The system quickly calculates the location of an earthquake, and we calculate the time it takes to reach geographic locations … We use grafana for all information generated in real time … coming from postgresql’s database … but we need something else…
Is there some kind of countdown counter to show the time in which people will feel the earthquake?
The end time would come from a postgresql database …

thanks in advance for any advice …