New Zealand’s long history with tsunamis shows just how real the threat is to coastal communities. Since the 1840s, at least 68 tsunamis have struck New Zealand’s shores, with six of them reaching over 5 meters in height, causing widespread damage. As the risk remains, understanding how to respond to a tsunami is crucial, especially if you live near or are visiting coastal areas. Being prepared and knowing how to react can make all the difference when every second counts.
Tsunami warning signals
- Prolonged Ground Shaking After an Earthquake:
Tsunamis are often triggered by underwater earthquakes. If you feel a strong or long-lasting earthquake (usually more than 20 seconds), treat it as a natural tsunami warning and take action immediately. - Unusual Sea Behavior:
Before a tsunami strikes, the ocean often behaves unusually. You might notice the water rapidly receding far from the shore or a sudden surge towards the land. - Tsunamis Come in Multiple Waves: Many people assume that the first wave of a tsunami is the largest, but subsequent waves can be just as powerful, or even more dangerous.
- Loud Roaring Sound
Some survivors of tsunamis describe hearing a loud roaring or rumbling sound, similar to a train or jet engine, just before the tsunami wave strikes.
Responding to Tsunami Warnings:
- Tsunami awareness in New Zealand
Tsunami warnings can come in two forms: natural signs, such as long or strong earthquakes, unusual sea behavior, and loud roaring sounds, and official alerts, which are broadcast through various channels. You can find more about Tsunami awareness and preparedness here. - Tsunami evacuation zones
Coastal areas are divided into different risk levels, and each zone has designated evacuation routes. Familiarise yourself with these zones, especially if you live near the coast or plan to visit.
If a tsunami warning is issued, move to higher ground at least 30 meters above sea level or 2 kilometers inland whenever possible.
- Official Alerts:
Alerts are sent directly to mobile phones in affected areas, offering crucial time to evacuate. Always follow the instructions from the Emergency Mobile Alert system provided in these alerts. - Act Fast:
A study of past tsunami events in New Zealand shows that people who act within the first 10 to 20 minutes of warning signals (whether natural or official) have a much higher chance of survival.
- Stay Away from the Coast:
Tsunamis often come in multiple waves, with the first not always being the most powerful, so it’s essential to avoid the coast until authorities declare it safe. High-risk areas like Gisborne and Hawke’s Bay on the East Coast of the North Island are particularly vulnerable due to their proximity to fault lines.
Tsunamis are unpredictable, but preparedness saves lives. After the 2016 Kaikōura earthquake, many coastal residents evacuated within minutes of feeling the strong shaking, avoiding disaster as tsunami waves followed shortly after.
Knowing your evacuation routes, acting fast, and staying away from the coast until it’s safe are all key to surviving a tsunami. Every second counts when you’re facing the power of the ocean.