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Earthquakes

The eastern coast of New Zealand gets hundreds of earthquakes every year. Most of them are never felt, but big earthquakes can cause a lot of damage. A large earthquake occurs somewhere in New Zealand every 10 years on average. In fact in New Zealand earthquakes are occurring continuously but most aren't large enough to be detected except by special equipment.

Hawke's Bay Earthquake 1931 - Hastings Street, Napier

An earthquake is caused by movements in the surface of our planet deep underground. The surface is made up of large pieces - called tectonic plates - that fit together like a jigsaw. New Zealand is on the join of two massive jigsaw pieces - the Pacific Plate and the Australian Plate.

Just off Hawke's Bay deep below the sea the Pacific Plate is sliding underneath the Australia Plate. This movement is very slow (about the same speed as your fingernails grow) but as rocks don't slide easily past each other, sometimes there is no movement for a time. Pressure builds up until something has to give, so when the plates finally move there's a sharp jolt which makes the ground shake - that's an earthquake.

Hawke's Bay has been one of the most seismically active regions of New Zealand in the 150 years since substantial written records began. Most moderate to large earthquakes have been on shallow (<45 km deep) faults, but a few, such as the June 1981 Hawke's Bay earthquake, were caused by rupture at greater depths. The largest historical earthquakes affecting Hawke's Bay are listed in Table B.

Previous Impacts in Hawke's Bay

1863 Southern Hawke's Bay

A Magnitude 7.0 earthquake occurred on 23 February 1863. It is the second largest earthquake to occur in Hawke's Bay since about 1843 with its epicentre near Waipawa. Personal accounts from witnesses reveal the occurrence of numerous landslides, liquefaction, and surface faulting.

1904 Cape Turnagain

On 9 August 1904 a Magnitude 6.7 earthquake, centred off Cape Turnagain, caused damage to chimneys, buildings and roads throughout southern Hawke's Bay from north of Napier to Masterton. Liquefaction, sand boils, landslides, and surface fractures were reported. Near Kopua and Te Aute there was noticeable subsidence and there may have been a small tsunami.

1931 Hawke's Bay

On 3 February 1931, one of the three largest historical earthquakes ever recorded in New Zealand struck Hawke's Bay and was felt strongly throughout the lower North Island. The magnitude 7.8 earthquake was produced by rupture on a northeast-trending buried fault, probably the Napier-Hawke Bay Fault. The epicentre (the point on the earth's surface vertically above where the earthquake initiated) was a little East of North of Napier, very close to the coast between Waipatiki and Tangoio Bluff. The depth of the earthquake is assumed to be 30 km and epicentre is just over 20 km from Napier. There was only a minor surface rupture along a 15 km stretch of the fault, but the underground faulting produced an uplifted area, 90 x 17 km and up to 2.7 m high.

In Hastings, about one metre of ground subsidence occurred. The Ahuriri Lagoon was raised 1-2 m and partially drained. Near Napier the coastline was raised and some boats moored in the harbour were left sitting on harbour floor rather than floating as a result of the uplift of the coast.

Hawke's Bay Earthquake 1931 - Railway Road, Hastings

The 'Hawke's Bay earthquake' was the most damaging quake to affect New Zealanders. Two hundred and fifty six people lost their lives, either from collapsing buildings or in the widespread fires that followed the earthquake. Many buildings at that time were constructed of unreinforced masonry or had poorly supported concrete facades that collapsed in the shaking.

Hawke's Bay Earthquake Stories

People who lived through the earthquake had some dramatic stories to tell.  Click Here to Read.

The fires that destroyed downtown Napier were left to burn after the water supply in town failed. All the bridges into town collapsed and the main roads into Hawke's Bay suffered severe damage. In all, the economic damage from the earthquake was $9.7 million (equivalent to about $300 million today).

The 1931 earthquake prompted a number of changes in New Zealand's approach to earthquake hazard management. New construction regulations were developed so that structures would be built to minimise damage from earthquake shaking. Although it was not implemented until 1942, the government began to develop a system of earthquake insurance and compensation, and civil defence strategies were enacted to ensure that public safety and relief would be taken care of in future earthquakes.

For more information on the 1931 Earthquake visit the Art Deco Website.

1932 Wairoa

A magnitude 6.9 earthquake, centred near Wairoa, occurred on 15 September 1932. It may have been caused by a new rupture along the northeast extension of the Napier-Hawke Bay Fault that ruptured in the 1931 Hawke's Bay earthquake. The shaking damaged buildings in Gisborne and Wairoa and caused the collapse of the Wairoa River bridge. The earthquake was accompanied by no known surface rupture but it triggered a number of landslides near and northeast of Wairoa.

Other earthquakes

Numerous other large earthquakes affecting Hawke's Bay have been documented since the middle of the nineteenth century. Some of the largest include the magnitude 7.0 Central Hawke's Bay earthquake of June 1921, a 7.3 aftershock to the Hawke's Bay earthquake on 13 February 1931, and the 7.6 Pahiatua earthquake in March 1934. Earthquakes in other areas have also caused damage in Hawke's Bay. In 1855 a Magnitude >8 earthquake in Wairarapa generated moderately strong felt intensities of shaking in Hawke's Bay although its epicentre was more than 200 km south of Napier, and a Magnitude >7 earthquake in the Bay of Plenty in October 1914 was widely felt in Hawke's Bay.

Numerous earthquakes in recent years have shaken Hawke's Bay, like the three significant earthquakes recorded in 2001. A Magnitude 5.8 quake with an epicentre close to Hastings on 15 October was widely felt, then a magnitude 5.0 quake on 24 October located 30 km northwest of Taupo was felt along the east coast of the North Island. On 8 December a magnitude 5.0 event located 30 km southwest of Gisborne produced a strong shake in many part of the region. These continuing earthquakes are warnings to be ready for the next big one.

Learn more

Learn more about what you should do before an earthquake occurs, and what to do during an earthquake at the national Civil Defence website.

Table B. Historical earthquakes with magnitude > 6 and felt MM intensities of VII or greater in Hawke's Bay

DateMagnitudeMM Intensity in Hawke's BayDistance from Napier (km)
15 Oct 18487.1>200
23 Jan 18558.0-8.2VI-VII>200
22 Feb 18637.5XIII-IX70
11 Oct 1892 6.0-6.3VII120
4 Dec 18986-6.2VII90
1 Aug 19036.0VII20
8 Aug 19046.7VI-VIII120
22 Nov 19147.0VI-VII225
28 Jun 19217.0VII60
7 May 19296.0V-VII140
12 Feb 19306.2VI-VIII120
2 Feb 19317.8VII-X30
8 Feb 19316.3VI-VII50
13 Feb 19317.3VI-VII40
15 Sep 19326.9V-X80
5 Mar 19327.6V-VII170
10 Mar 19346.0VII120
31 Jan 19586.1IV- VII80
13 May 19906.2V-VIII110
22 Aug 20017.0V-VI820