Tsunami warning system works

A global tsunami warning system now in place did its job Wednesday as two large earthquakes in the Indian Ocean triggered alerts to nearby coastal cities. The quakes this time did not cause major damage. How the system works:

Tsunami warning system works
Indian Ocean network

Warning system elements

Sorting the data

Pressure readings on the seafloor are reported every 15 minutes. When the sensor detects an event, data are transmitted every 15 seconds and then at longer intervals. Transducer converts electronic data into an acoustic signal for transfer to a buoy.

On the surface

A system of buoys is anchored loosely to the seafloor by a swivel-and-chain system that allows them to move with swells and tides. They contain transducers that allow them to receive data from the pressure recorder. They are linked to satellites that maintain a constant position.

Indian Ocean network

Close to the source

Buoys are deployed along the edges of the Earth’s tectonic plates where seismic activity is common.