A tsunami is a sea wave triggered by a large-scale displacement of the sea floor. They are most commonly caused by earthquakes but can also be caused by major underwater (or 'submarine') landslides or volcanic eruptions. They can strike any coast at any time. Tsunamis can move as fast as a jet plane across the open ocean and can hit land with waves higher than 20 metres. Water can wash inland for several kilometres in flat lying areas and move up streams and rivers, destroying everything in its path. Waves may continue to strike the shoreline for many hours and dangerous currents can continue for several days. Although a tsunami can't be prevented, its impact can be reduced when communities understand the risks, receive timely warnings and know how to respond.

The coastline in Sulawesi, Indonesia is strewn with toppled palm trees and debris following a devastating tsunami in 2018

Emergency appeals

Do you know how to prepare for a tsunami?

Do's and don'ts

  • Learn about the local risks and history of tsunamis
  • Prepare an evacuation plan and route
  • Learn and be ready to act on official tsunami advisories and alerts
  • Don't return home until authorities say it's safe to do so
  • Stay away from the coast, tidal estuaries, rivers and streams
  • Beware of secondary hazards, such as contaminated water
  • Practise an evacuation drill at least once a year

Watch: how to prepare for a tsunami