The Alpine Fault is clearly visible from space, running along the western edge of the Southern Alps from the southwestern coast towards the northeastern corner of the South Island. The Southern Alps is a Mountain range which runs along the western side of the South Island of New Zealand. The South Island is the larger of the two major islands of New Zealand, the other being the more populous North Island.

Map of Zealandia Continent

This map, coloured by elevation, shows how the Alpine Fault affects the topography of the South Island's West Coast. Naming To New Zealanders the term 'The Coast' generally refers to the West Coast of the South Island, and 'Coasters' to those that live there The region shown is 495 km (307 mi) long; northwest is at the top.

The Alpine Fault is a geological fault, known as a right-lateral strike-slip fault, that runs almost the entire length of New Zealand's South Island. In Geology a fault, or fault line, is a planar rock fracture which shows evidence of relative movement New Zealand is an Island country in the south-western Pacific Ocean comprising two main landmasses (the North Island and the South Island The South Island is the larger of the two major islands of New Zealand, the other being the more populous North Island. It forms a transform boundary between the Pacific Plate and the Indo-Australian Plate. A transform fault is a fault which runs along the boundary of a Tectonic plate. The Pacific Plate is an oceanic Tectonic plate beneath the Pacific Ocean. The Indo-Australian Plate is a major Tectonic plate that includes the continent of Australia and surrounding Ocean, and extends northwest to include the Earthquakes along the fault, and the associated earth movements, have formed the Southern Alps. The Southern Alps is a Mountain range which runs along the western side of the South Island of New Zealand. The uplift to the southeast of the fault is due to an element of convergence between the plates meaning that the fault has a significant high-angle reverse oblique component of its displacement.

The Alpine Fault is believed to align with the Macquarie Fault Zone in the Puysegur Trench off the southwestern corner of the South Island. The Macquarie Fault Zone is a major right lateral-moving Transform fault along the seafloor of the south Pacific Ocean which runs from New Zealand southwestward From there, the Alpine Fault runs along the western edge of the Southern Alps, then splits into three parallel faults north of Arthur's Pass, merging into the Kermadec-Tonga Subduction Zone in the Hikurangi Trench off the coast of the North Island. Arthur's Pass (el 920 m is a Mountain pass in the Southern Alps of the South Island of New Zealand. The Kermadec-Tonga Subduction Zone is a convergent Tectonic plate boundary which stretches from the North Island of New Zealand northward and includes The Hikurangi Trench (also called the Hikurangi Trough) is a linear deep in the Pacific Ocean off the east coast of the North Island of New Zealand

Average slip rates in the fault's central region are about 30mm a year, very fast by global standards.

Historic earthquakes

The Alpine Fault and its northern offshoots have experienced sizeable earthquakes in historic times:

• 1848 - Marlborough. Estimated magnitude = 7. 5.
• 1888 - North Canterbury. Estimated magnitude = 7. 3.
• 1929 - Arthur's Pass. Estimated magnitude = 7. 1.
• 1929 - Murchison. Estimated magnitude = 7. 8.
• 1968 - Inangahua. Estimated magnitude = 7. 1.
• 2003 - Fiordland. Estimated magnitude = 7. 1.

Major ruptures

Over the last thousand years, there have been four major ruptures along the Alpine Fault causing earthquakes of about magnitude 8. These occurred in approximately 1100, 1450, 1620 and 1717 AD, at intervals between 100 and 350 years. The 1717 quake appears to have involved a rupture along nearly 400km of the southern two thirds of the fault. Scientists say that a similar earthquake could happen at any time as the interval since 1717 is longer than between the earlier events. [1]

Large ruptures can also trigger earthquakes on the faults continuing north from the Alpine Fault.

See also

• Earthquake
• Plate tectonics
• Seismology
• Earthquakes in New Zealand

References

External links

University of Otago Geology Department:

• Overview
• Virtual Field Trip
• Potential effects of major rupture

Institute of Geological & Nuclear Sciences Limited (GNS):

• Summary from the New Zealand Active Faults Database (includes a map, photos, and references)
• Map of New Zealand's Historic Earthquakes
• FAQ on Alpine Fault
• Press release, 10 September 1998

Miscellaneous:

• Earthquakes and Tectonics in New Zealand