An undersea earthquake causes disturbance to both the sea floor and body of
ocean above it. Seismic waves (in red) travel much faster than tsunami waves
away from the earthquake source. Earthquakes are detected through a network
of seismic monitoring stations. Any resulting tsunami are then verified by
sea-level monitoring stations and deep-ocean tsunami detection buoys. The seismic
monitoring stations can determine the location and depth of earthquakes that
have the potential to cause tsunami. The sea-level gauges and deep-ocean detection
buoys measure any abnormal changes in sea level to verify if a tsunami has
Deep-ocean tsunami detection buoys are one of two types of instruments used by the Bureau to confirm the existence of tsunami generated by undersea earthquakes. These buoys observe and record changes in sea-level out in deep ocean. This enhances the capability for early detection and real time reporting of tsunami before they reach land. These systems are capable of measuring sea-level changes of less than a millimetre in the deep ocean.
A typical tsunami buoy system comprises of two components, the pressure sensor anchored to the sea floor and the surface buoy. The sensor on the sea floor measures the change in height of the water column above by measuring associated changes in the water pressure. This water column height is communicated to the surface buoy by acoustic telemetry and then relayed via satellite to the JATWC.
For more information visit the Bureau of Meteorology website www.bom.gov.au