Alpine Fault History - Alpine Fault

The Alpine Fault is 600km up the spine of the South Island N.Z, and is between Pacific and Australian Plates.

The fault last ruptured in 1717 AD, and of a magnitude 8. There have been four ruptures in the past 900 years – 1100AD, 1450AD, 1620AD and the latest 1717AD, all producing an earthquake of about magnitude 8.

The Alpine fault moves horizontal about 30m per 1000 years, very fast by global standards. Every time is has ruptured; it has moved vertically aswell lifting the Southern Alps with it. In 12 million years the Southern Alps have been uplifted by 20 kilometres and the face pace of erosion has kept their highest point below 4000 metres.

The Alpine Fault has a very high probability (estimated at 30%) of rupturing in the next 50 years (from 2012). The earthquake will be one of the biggest earthquakes since European settlement of N. Z, with a major impact on the lives of many people. The average interval between large quakes on the fault was 330 years. The last rupture was 300 years ago.

The Alpine Fault has many other faults coming off it, like vines. In the mid to top part of the South Island there is Wairau Fault, Awatere Fault, Clarence Fault and Hope Fault all part of the Marlborough Fault System. All of these faults could also rupture at the same time if there is enough energy to release them.