How deep-ocean buoys help detect tsunamis
The tsunami detection buoy system consists of a pressure sensor anchored to the sea floor and a surface buoy for transmitting data. The sensor on the sea floor measures changes in water column height and pressure. It's so precise it can measure sea-level changes of less than one millimetre.
The system can operate in 2 modes. In standard mode, the system transmits sea-level data every 15 minutes by satellite. The 15-minute interval helps save battery power and extend the buoy's life. The average buoy's life is 2–4 years. We replace them every 1–2 years.
Event mode is activated when the pressure sensor detects a tsunami wave, or a seismic wave caused by an earthquake. In event mode, sea-level data transmits at one-minute intervals, so we can track and verify the threat fast.
We can also activate event mode manually at any time if there's a possible threat, or for research purposes.
Video: Australia's tsunami detection system
(Shows a boat next to a yellow buoy. A cable goes down to the sea floor and two anchors hold the buoy in place.)
Deployment of tsunameter
(Shows a tsunameter leaving the boat and falling to the sea floor next to the anchored surface buoy.)
Earthquake
(Shows everything shaking.)
Seismographs detect potential seismic activity
(Shows a building labelled JATWC or Joint Australian Tsunami Warning Centre where the seismographs are located.)
Tsunami
(Shows a wave passing over the tsunameter.)
Detects change in pressure
(Shows sensors on the tsunameter detecting change.)
(Shows a signal passing from the tsunameter to the surface buoy and up to a satellite in the sky. This beams it back to the JATWC building.)
Where we place the buoys
We place buoys in regions where undersea earthquakes are likely to happen. This is to the northwest, northeast and southeast of Australia, along subduction zones. Subduction zones are where tectonic plates move under each other.
More ways to detect tsunamis
The buoys are one part of our sea level observing system. We also rely on coastal sea level stations, sometimes called tide gauges, installed nearshore. Combining different types of sea level observations helps us confirm a real tsunami threat. This helps reduce the risk of issuing a false tsunami warning.
The international community can access data from our buoys and tide gauges in real-time through the World Meteorological Organization's Global Telecommunication System. All global buoy data can be found at the U.S. National Data Buoy Center.