Tsunami

Tsunamis are waves generated by earthquakes, landslides, or volcanoes in the sea floor. Such submarine activity in the Pacific Ocean is monitored and collated by the Pacific Tsunami Warning Centre in Honolulu. On three occasions earthquakes off the coast of Chile caused damage in New Zealand, but the largest waves occurred in 1947 after an off-shore earthquake generated tsunamis near Gisborne which reached 9-11 metres. The last major tsunami in our region followed the 1855 Wairarapa earthquake, when the Wellington harbour oscillated up and down about 4 metres every 20 minutes for about 12 hours.

• Civil Defence sirens would alert the community to a tsunami if time permits.
• An Email and Text will be sent via the Readynet Network.
• Public information would be broadcast via radio and TV.
• People in low-lying areas may be evacuated to higher ground.
• Follow any instructions and take documents, pets and your Survival Items.

Facts On Tsunami

• Tsunami that strike coastal areas are almost always caused by earthquakes. Underwater volcanic eruptions or landslips can also generate tsunami. These tsunami sources may occur far away or very near where you live.

• Some tsunami can be very large. In coastal areas they can reach heights of 10 metres or more and they can move inland several hundred metres.

• A tsunami consists of a series of waves. Often the first wave may not be the largest. The danger from a tsunami can last for several hours after the arrival of the first wave.

• Tsunami can move faster than a person can run. In deep water, waves may reach speeds greater than 600 kms per hour.

• Sometimes a tsunami causes the water near shore to recede, exposing the ocean floor. If you see this, leave immediately.

• The force of some tsunami is enormous. Large rocks weighing several tonnes along with boats and other debris can be moved inland hundreds of metres by the tsunami. Homes and other buildings are destroyed. All this material and water moves with great force and can kill or injure people.

• Tsunami can occur at any time, day or night.

• Tsunami can travel up rivers and streams that lead to the ocean.

When A Tsunami Threatens, What Should You Do?

Locally Generated Tsunami

If you are in the vicinity of the beach and feel a strong earthquake or notice the sea receding unusually, IMMEDIATELY move to higher ground. You may only have a few minutes.

• Take yourself and others to higher ground the higher the better at least 35 metres above sea level is best.

• If you cannot go higher, go inland at least 1.5 kilometres

• DO NOT return for at least one hour OR until told to by the authorities.

• DO NOT wait for a tsunami bulletin before moving to higher ground.

• Avoid rivers and inlets because they magnify tsunami waves

Long Distance Tsunami

Bulletins will be given about tsunami if they are coming from far away. These warnings come from the Pacific Tsunami Warning Centre in Hawaii.

The tsunami warnings will be passed to you via a warning signal (sting) on your local radio or via a loud hailer or warning siren.

• Turn on your radio and follow all instructions.

• Take any essential items with you if you are told to evacuate.

• DO NOT go to the beach to watch the waves come in.

• If you are on a boat, stay on the water - DO NOT return to port. Tsunami can cause rapid changes in water levels and unpredictable currents in ports and harbours.

For further information and advice look in the yellow pages or contact your local council.