Earthquakes

Taranaki has a number of active fault lines particularly in the Inglewood, Waverley and Oaonui areas as well as off-shore.

Around 200-300 earthquakes are recorded each year in Taranaki, which accounts for about 2% of the total number of earthquakes located in New Zealand in a typical year. In Taranaki, up to ten of those might be large enough to be felt by residents.

Most of the shallow earthquakes in Taranaki are centred west of Mt Taranaki (Cape Egmont Fault Zone), with only a few events beneath or close to the mountain. Deep earthquakes are mainly located in the Hāwera area, caused by the bottom of the Pacific Plate subducting beneath the North Island. In the east of Taranaki a band of activity continues almost to Mt Ruapehu. This is considered normal seismicity for Taranaki and the trends have remained unchanged since monitoring began in 1994. No earthquakes have been recorded that might indicate ongoing volcanic proccess or precursors of an eruption of Mt Taranaki.

GNS Science calculates the annual likelihood of a magnitude 6.0 earthquake (large enough to damage buildings and move furniture) to be 5% in South Taranaki and 3% in the north. However, a large, damaging earthquake could occur at any time, and may be followed by aftershocks that continue for weeks or months.

Ruptures on the Inglewood fault have seen vertical movements of 1-2 metres whilst the Waverley fault can produce vertical movements of more than 3 metres. The likelihood of these events is described in the hazard and risk analysis as 'possible'.

Most earthquake-related injuries and deaths result from falling debris, flying glass and collapsing structures such as buildings and bridges. Earthquakes can also trigger landslides, avalanches, flash floods from dam bursts, fires and tsunami.