You know when a tsunami might hit when:
- There is an earthquake first – though it might happen far away and not be felt everywhere. Landslides or volcanoes can also trigger tsunamis.
- Many people who have experienced a tsunami report hearing a loud roaring sound, similar to a freight train or aeroplane.
- The water retreats from the shore, exposing seafloor. This is caused by tsunamis taking in water as they approach land. Many people have died by going to look at the bare seafloor exposed by the retreating ocean before a tsunami strikes`.
Tilly Smith (far right) and her family at a memorial service marking the first anniversary of the 2004 Indian Ocean earthquake and tsunami.
In 2004, during the Indian Ocean earthquake, Tilly Smith, a 10-year-old British girl on holiday in Thailand, spotted the retreating shoreline.
She warned her parents and the beach was evacuated.
After learning about tsunamis in her geography lesson, her quick action saved hundreds of people before the tsunami struck.