Tsunami Hazards and Evacuation Zones

With the recent East Cape earthquake still present in memory, it is an appropriate time for people in coastal areas and identified tsunami evacuation zones to review their plans. This short video may help.

Friday, 9th September 2016

The magnitude 7.1 earthquake which struck off East Cape (125 km north-east of Te Araroa) on Friday September 2nd generated a small tsunami that was measured at 30 cm at East Cape.

This was not the case in 1947 when two earthquakes centred off the coast north of Gisborne generated damaging tsunami waves. The magnitude 7.1 quake of the 26th of March 1947 generated a significant local tsunami – the first wave swept ashore just seven minutes after the earthquake, with the largest wave arriving shortly after.

This highlights the fact that residents in tsunami-prone areas near the epicentre of a large undersea earthquake will have no official warning if a tsunami is generated.

A short video prepared by GNS in 2014 describes the types of tsunami hazards faced by New Zealand and possible warning times. It also describes the tsunami evacuation zone maps that have been prepared by local councils and the action that residents of those zones should take in the event of a large local or distant earthquake that might generate a tsunami.

Maps showing tsunami evacuation zones are available on council websites.

The four-minute video prepared by GNS Science can be found here.

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