How to know if a tsunami is coming

One of the signs of a potential tsunami is the occurrence of a very large earthquake that lasts for more than 20 seconds. If an area has been shaken by a very large earthquake, one should be on alert that shorelines located within the radius of the earthquake’s epicentre, may be hit by a tsunami.

Deep-ocean tsunami detection buoys are one of two types of instrument used by the Bureau of Meteorology (Bureau) to confirm the existence of tsunami waves generated by undersea earthquakes. These buoys observe and record changes in sea level out in the deep ocean.

Scientists estimate that almost three quarter of the world tsunamis occur in the Pacific Ocean, where the megathrusts (subduction zones) are so common (Aleutian Islands, Alaska, Chile, Philippines, Japan etc).

Where do tsunamis most often occur in the world? Tsunamis occur most often in the Pacific Ocean and Indonesia because the Pacific Rim bordering the Ocean has a large number of active submarine earthquake zones.