M 7.1 Inangahua Fri, May 24 1968

The 1968 Inangahua earthquake caused widespread damage and was felt over much of the country.



Geologist John Foster stands at the destroyed road, SH6 east of Inangahua. [GNS Science]

Geologist John Foster stands at the destroyed road, SH6 east of Inangahua. [GNS Science]

These railway lines, originally straight, were left buckled after the earthquake, distorted by the intense ground motion. [GNS Science]

These railway lines, originally straight, were left buckled after the earthquake, distorted by the intense ground motion. [GNS Science]

As well as buckling railways lines, the force of the earthquake was enough to derail this train, causing it to topple over. [GNS Science]

As well as buckling railways lines, the force of the earthquake was enough to derail this train, causing it to topple over. [GNS Science]

At Whitecliffs, a limestone bluff collapsed, crushing a farmhouse and killing two people. The material deposited in 1968 is still visible at the base of the bluff, covered in vegetation. [Private collection, Simon Nathan]

At Whitecliffs, a limestone bluff collapsed, crushing a farmhouse and killing two people. The material deposited in 1968 is still visible at the base of the bluff, covered in vegetation. [Private collection, Simon Nathan]

The surface of this road gave way when the earthquake caused a mine drainage tunnel to collapse. [GNS Science]

The surface of this road gave way when the earthquake caused a mine drainage tunnel to collapse. [GNS Science]

Geologists measure the vertical movement across a rupture created by the earthquake. The side they are standing on has moved downwards relative to the rest of the road. [GNS Science]

Geologists measure the vertical movement across a rupture created by the earthquake. The side they are standing on has moved downwards relative to the rest of the road. [GNS Science]

Most of New Zealand felt the earthquake that struck the town of Inangahua in 1968. It was centred about 15 km north of Inangahua, but intensities of MM 4 and greater were recorded as far south as Otago and in almost all of the North Island, with the exception of areas in the north-east. Close to Inangahua, where intensities reached at least MM 10, the quake caused widespread destruction. Fortunately, the area’s small population meant casualties were minor, but most structures, including wooden houses, roads and bridges, suffered extensive damage in the quake. Underground pipes broke under the strain, and railway lines twisted and buckled, derailing two trains. One hundred kilometres of track later had to be replaced.

The quake also triggered large landslides in the surrounding slopes, one of which claimed the lives of two people. Inangahua and Westport were evacuated when another massive slip dammed the Buller River, raising the river 30m above its normal level, causing fears that a sudden failure of the dam would flood these downstream settlements. Due to the number of roads and bridges that had collapsed or been blocked in the quake, including the newly constructed Buller Gorge Highway, 235 people had to be airlifted to safety.

Numerous aftershocks followed the quake, including 15 that were magnitude 5 or greater and occurred within a month of the initial shock.