The 1929 Arthur's Pass earthquake occurred at on 9 March. The sparsely settled region around Arthur's Pass of the Southern Alps shook for four minutes. Tremors continued almost continuously until midnight and sporadic strong aftershocks were felt for several days. The earthquake was measured at 7.1 on the

Richter magnitude scale The Richter scale —also called the Richter magnitude scale, Richter's magnitude scale, and the Gutenberg–Richter scale—is a measure of the strength of earthquakes, developed by Charles Francis Richter and presented in his landmark 1935 ...

and the intensity of shaking in the epicentral region has been assessed from historical records as VIII (''Severe'') on the Modified Mercalli Scale. Intensities of VI (''Strong'') were observed in

Christchurch Christchurch ( ; mi, Ōtautahi) is the largest city in the South Island of New Zealand and the seat of the Canterbury Region. Christchurch lies on the South Island's east coast, just north of Banks Peninsula on Pegasus Bay. The Avon River / ...

and Westport. The earthquake occurred on the Poulter Fault, which was not identified and mapped until 2001.

Tectonic setting

New Zealand lies along the boundary between the Australian and

Pacific plate The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At , it is the largest tectonic plate. The plate first came into existence 190 million years ago, at the triple junction between the Farallon, Phoenix, and Iza ...

s. In the

South Island The South Island, also officially named , is the larger of the two major islands of New Zealand in surface area, the other being the smaller but more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman ...

most of the relative displacement between these plates is taken up along a single dextral (right lateral)

strike-slip fault In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...

with a major

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component, the Alpine Fault. In the

North Island The North Island, also officially named Te Ika-a-Māui, is one of the two main islands of New Zealand, separated from the larger but much less populous South Island by the Cook Strait. The island's area is , making it the world's 14th-largest ...

the displacement is mainly taken up along the

Kermadec-Tonga subduction zone The Kermadec-Tonga subduction zone is a convergent plate boundary that stretches from the North Island of New Zealand northward. The formation of the Kermadec and Tonga Plates started about 4–5 million years ago. Today, the eastern boundary ...

, although the remaining dextral strike-slip component is accommodated by the

North Island Fault System The North Island Fault System (also known as North Island Dextral Fault Belt or NIFS) is a set of southwest–northeast trending seismically-active faults in the North Island of New Zealand that carry most of the dextral (right lateral) strike- ...

. The Poulter Fault runs for approximately 50 km east-north-east from near the confluence of the Bealey and Mingha rivers to the valley of the South Hurunui River. Between 16 km and 36 km of the fault ruptured, with dextral displacement of up to 4 metres and dip-slip displacement of 1–2 metres (North side up).

Effects

Numerous landslides were triggered, damaging the

Midland Railway The Midland Railway (MR) was a railway company in the United Kingdom from 1844. The Midland was one of the largest railway companies in Britain in the early 20th century, and the largest employer in Derby, where it had its headquarters. It am ...

and blocking roads. The highway connecting Canterbury and the West Coast via Arthur's Pass was closed for several months. Many water tanks and chimneys were damaged or toppled. Two years after the earthquake, trampers in the Otahake Valley discovered that a 900m high section of the side of a mountain had collapsed, blocking the valley and sending debris 5 km downstream. Although () this is one of the ten largest land-based earthquakes to strike New Zealand since European settlement, it was overshadowed by the more deadly

1929 Murchison earthquake The 1929 Murchison earthquake occurred at 10:17 am on 17 June. It struck the Murchison region of the South Island, with an estimated magnitude of 7.3, and was felt throughout New Zealand. There were 17 deaths, mostly as a result of landsli ...

a few months later.

References

External links

Photograph of Falling Mountain landslip – Te Ara Encyclopedia of New Zealand
* {{DEFAULTSORT:1929 Arthur's Pass Earthquake 1929 Arthur's Pass Arthurs Pass Earthquake, 1929 New Zealand – Arthur's Pass History of the Canterbury Region

Tectonic setting

Effects

See also

References

External links