A tsunami is a series of sea waves caused by an earthquake, landslide or volcanic eruption beneath or near the ocean. Tsunami is a Japanese word meaning “great wave in harbour”. Tsunami are large ocean waves usually created by a sudden movement or rupture in the ocean floor. These can be caused by earthquakes, underwater landslides and underwater volcanic eruptions. They occur a few times a year, but generally we don’t notice them. Larger tsunami can cause coastal flooding, erosion, damage to buildings and loss of life in extreme cases.
How much warning will you have?
There are three distinct types of tsunami – distant, regional and local. In the case of a distant tsunami, we will have more than three hours warning. A regional tsunami will be between one and three hours away, while a local tsunami – the most dangerous – may only give us a few minutes warning.
Tsunami warning
Here are the ways you will know that a tsunami is approaching.
- The Ministry of Civil Defence & Emergency Management will issue a national warning on the television and radio
- You will receive a warning from your local council or Civil Defence Emergency Management Group
- If you are at the coast and you feel a strong earthquake, see the sea receding (the waterline moving away from the shore), the sea bubbling or making a roaring sound, move to higher ground immediately.
- Be aware that there may be more than one wave, sometimes as many as seven, and it may not be safe for up to 24 hours. The waves that follow the first one may also be bigger
Before a Tsunami
- If you live in a coastal area, check with your council about the level of risk a tsunami may pose
- Check with your local Civil Defence Emergency Management Group to find out what warning procedures you should expect
- Develop a Household Emergency Plan and ensure you have a Getaway Kit ready should you need to leave in a hurry
- Know where the nearest high ground is and how you will reach it. Higher ground should be at least 35 metres above sea level or at least 1km inland. Plan your escape route now with your household
- If you are buying land, investing or building in a coastal area, talk to your council about the risks of a tsunami, coastal storm surge and erosion
During a tsunami
If you haven’t done so already, move immediately to the nearest higher ground.
After a tsunami
Listen to the radio for civil defence advice
Do not go down to the sea until you have been told it is safe to do so