5.0 earthquakes and aftershocks in 1997, which occurred close to the central part of the Alpine fault. Strike-slip faults have walls that move sideways, not up or down. [12] The 1717 quake appears to have involved a rupture along nearly 400 kilometres (250 mi) of the southern two-thirds of the fault. Search. There have been no major historical earthquakes on the Alpine Fault. Offshore investigations have allowed the Alpine Fault to be accurately mapped immediately west of Fiordland. a!. The Southern Alps had not yet formed and most of New Zealand was covered in water. This idea coupled with the displacement on the fault proposed that the earth's surface was in relatively rapid constant movement and helped to overthrow the old geosynclinal hypothesis in favour of plate tectonics. This item has been provided for private study purposes (such as school projects, family and local history research) and any published reproduction (print or electronic) may infringe copyright law. [2] In outcrop the fault zone is overlain by mylonites which formed at depth and have been uplifted by the fault.[8]. You can pick out the line of the Alpine Fault on this satellite image of the South Island. This study analyzes 195 earthquakes recorded during the 6 month duration of the Southern Alps Passive Seismic Experiment (SAPSE) in 1995/1996 and two M L 5.0 earthquakes and aftershocks in 1997, which occurred close to the central part of the Alpine fault. Richard H. Sibson from the same university also used the Alpine Fault to refine his nomenclature of fault rocks which gained international adherence. This page was last edited on 6 December 2020, at 19:25. The Alpine Fault has a high probability (estimated at 30%) of rupturing in the next 50 years. Source: NIWA – National Institute of Water and Atmospheric Research, Eileen McSaveney, 'Active faults - Building on or near active faults', Te Ara - the Encyclopedia of New Zealand, http://www.TeAra.govt.nz/en/diagram/4361/alpine-fault-offshore-from-fiordland (accessed 16 December 2020), Story by Eileen McSaveney, published 12 Jun 2006, reviewed & revised 1 Aug 2017. The hanging wall slides down relative to the footwall. The content of this field is kept private and will not be shown publicly. The uplift is due to an element of convergence between the plates, meaning that the fault has a significant high-angle reverse oblique component[clarification needed] to its displacement. Wells, A.; Yetton, M.T. [9] However, it is now inferred by multiples lines of evidence that the Alpine Fault ruptures creating major earthquakes about every few hundred years. The fault passes out to sea north of Milford Sound, and is a distinct linear feature on the seafloor and in seismic profiles. [1] This, along with isostatic constraints, has kept the Southern Alps less than 4000 m. Uplift on the Alpine Fault has led to the exposure of deep metamorphic rocks near the fault within the Southern Alps. Where were New Zealand’s largest earthquakes? [16] A 2018 study says that a significant rupture in the Alpine Fault could lead to roads (particularly in or to the West Coast) being blocked for months, as with the 2016 Kaikoura earthquake, with problems in supplying towns and evacuating tourists. The Alpine Fault is a geological fault that runs almost the entire length of New Zealand's South Island and forms the boundary between the Pacific Plate and the Indo-Australian Plate. Other articles where Normal fault is discussed: fault: Normal dip-slip faults are produced by vertical compression as Earth’s crust lengthens. Find a local Authorised Alpine Specialist Dealer in your area. The fault system extends northeast from the Alpine Fault near St Arnaud, through the eastern part of Tasman District and into Nelson City and Tasman Bay (Fig. In between is a sideways tear, the Alpine Fault. The Alpine Fault in the central region forms dipping sections with oblique thrust characteristics connected by sections with mainly dextral strike-slip, resulting in a "zigzag" outcrop pattern. 1). © Crown Copyright. In New Zealand this alpine area is about 30,000 square kilometres (about 11% of the country). [27] It was led by New Zealand geologists Rupert Sutherland, John Townsend and Virginia Toy and involves an international team from New Zealand, Canada, France, Germany, Japan, the United Kingdom, and the United States. [27][28] One of the goals of the project was to use the deformed rocks from the fault zone to determine its resistance to stress. In the new study, the interval between earthquakes ranged from 160 to 350 years and the probability of an earthquake occurring in the following 50 years was estimated at 29 per cent. All text licensed under the Creative Commons Attribution-NonCommercial 3.0 New Zealand Licence unless otherwise stated. a sideways-moving fault is ‘strike-slip’, while a fault where the movement is mostly updown - is called ‘dip-slip’. Earthquakes along the fault, and the associated earth movements, have formed the Southern Alps. [10] So while earthquakes are an important part of Māori oral tradition, no stories have been passed down about South Island earthquakes. The last rupture of the Hope Fault was in 1888 when an earthquake with an estimated mome7.3 nt magnitude of 7- produced fault slip of about 2.5 m in the horizontal direction (Figure 4). [2] At the same time, Harold Wellman proposed the 480 km (300 miles) lateral displacement on the Alpine Fault. There have been no major earthquakes on the Alpine Fault in historic times, its southern and northern offshoots have, however, experienced sizable earthquakes: In 2012, GNS Science researchers published an 8000-year timeline of 24 major earthquakes on the (southern end of the) fault from sediments at Hokuri Creek, near Lake McKerrow in north Fiordland. In the North Island, alpine terrain is limited to the volcanoes o… Convergence on the plate boundary along the Alpine Fault ranges from a vector trending 084° at a rate of 45 mm yr-1 (Norris et. All non-text content is subject to specific conditions. [17][18][19] District councils along the West Coast and in Canterbury have commissioned studies and begun preparations for an anticipated large earthquake on the Alpine Fault. ; Duncan, R.P. [26][27] It was a $2.5 million international research project designed to drill 1.3 km to the fault plan in two months. [clarification needed] Most of the movement along the fault occurs in this zone. An Otago geologist's draft manuscript suggests there's a tectonic fault system off the South Island's east coast potentially comparable in size to the Alpine Fault. Scientists say that a similar earthquake could happen at any time as the interval since 1717 is longer than between the earlier events. The diagram was created for the purpose of the current study. Most of the alpine area is in the South Island, where several mountain peaks in the Southern Alps are higher than 3,000 metres. Commercial re-use may be allowed on request. ", "DEEP FAULT DRILLING PROJECT-2 FAQs / drill probe in Alpine Fault / Media Releases / News and Events / Home – GNS Science", "Extreme hydrothermal conditions at an active plate-bounding fault", "Potential earthquake triggering in a complex fault network: the northern South Island, New Zealand", Alpine Fault research in the Department of Geology. These had previously been determined to have occurred in approximately 1100, 1430, 1620 and 1717 CE, at intervals between 100 and 350 years. In the northeastern South Island, especially in the Kaikoura District, a substantial part of the plate movement is distributed on a series of large strikeslip faults east - of the Alpine Fault. In earthquake terms, the 850 kilometres (530 mi) long fault is remarkably consistent, rupturing on average every 330 years, at intervals ranging from 140 years to 510 years. The Alpine Fault then runs the length of the South Island just west of the Southern Alps to near Lewis Pass in the central northern section of the island. The Māori arrived in New Zealand c.1300 but never reached a high population density in the colder South Island. It is the responsibility of the user of any material to obtain clearance from the copyright holder. The Next Alpine Fault Earthquake in New Zealand, https://en.wikipedia.org/w/index.php?title=Alpine_Fault&oldid=992720605, Geographic areas of seismological interest, Articles with dead external links from June 2020, Articles with permanently dead external links, Short description is different from Wikidata, Wikipedia articles needing clarification from November 2020, Creative Commons Attribution-ShareAlike License, 2003 – Fiordland, estimated magnitude = 7.1. It passes out to sea just north of Milford Sound, and marks the western edge of northern Fiordland. The dominant movement on the fault is horizontal as shown by circle symbols at the base of the figure (arrow away/towards). Diagram showing a transform fault with two plates moving in opposite directions. [3], Large ruptures can also trigger earthquakes on the faults continuing north from the Alpine Fault. The Alpine fault is the Pacific‐Australian plate boundary in the South Island of New Zealand. Ensure your Alpine product is covered by our limited warranty* Register. The Hope Fault is thought to represent the primary continuation of the Alpine Fault. ; and Stewart, G.H. In the north, the fault trends offshore and into thrust type, "where tsunami can be born". The Alpine Fault forms part of the on-land Pacific-Australian plate boundary. This study analyzes 195 earthquakes recorded during the 6 month duration of the Southern Alps Passive Seismic Experiment (SAPSE) in 1995/1996 and two M₁. Between 25 and 12 million years ago the movement on the proto-Alpine Fault was exclusively strike-slip. The dominant movement on the fault is horizontal as shown by circle symbols at the base of the figure (arrow away/towards). The Alpine Fault is a major dextral-reverse fault that has produced large earthquakes (c. Mw=7.9) every 200–400 years with the last one in 1717 AD (Figure 3). Normal faults are common; they bound many of the mountain ranges of the world and many of the rift valleys found along spreading margins… Download the latest software for your system or device. (1999). [5] The Alpine Fault is not a single structure but often splits into pure strike-slip and dip-slip components. It was during this time that the cyclicity of the Alpine Fault earthquakes and meaning of the increase in metamorphic grade towards the fault was discovered and refined. The Australian plate is sliding horizontally towards the north-east, at the same time as the Pacific plate is pushing up, forming the … The alpine zone is usually defined as the area between the upper limit of trees (the timberline or the treeline) and the lower limit of permanent snow. [1] The Southern Alps have been uplifted on the fault over the last 12 million years in a series of earthquakes. Although most of the plate movement is concentrated at the subduction zones and the Alpine Fault, there is a wider zone of deformation, marked by numerous active faults, shown by thin red lines (from New Zealand Active Faults Database (NZAFD)). [27] Researchers also planned to install long term equipment for measuring pressure, temperature and seismic activity near the fault zone. However, most of the motion on the fault is strike-slip (side to side), with the Tasman district and West Coast moving North and Canterbury and Otago moving South. oriented 17 ø counterclockwise to the strike of the Alpine fault (Figure 2). In between earthquakes, the Alpine Fault is locked. Read more. Diagram 4 above represents the layering of these rock types and their exposure to the west of the Southern Alpine Main Divide by uplifting at the Alpine Fault border). Transform fault (the red lines) A transform fault or transform boundary is a fault along a plate boundary where the motion is predominantly horizontal. Spot the fault. [4], The Indo-Australian Plate is subducting towards the east south of the South Island and the Pacific Plate is subducting towards the West to the north. [22], Richard Norris and Alan Cooper from the Department of Geology, University of Otago conducted extensive research on the structure and petrology of the Alpine Fault respectively throughout the later 20th and early 21st centuries. Software Updates. The Alpine fault is the Pacific-Australian plate boundary in the South Island of New Zealand. [22] The fault was officially named the Alpine Fault in 1942 as an extension of a previously mapped structure. The Alpine Fault is a mature, dextral strike-slip fault that marks the western boundary of the Southern Alps. [20][21], In 1940 Harold Wellman found that the Southern Alps were associated with a fault line approximately 650 km (400 miles) long. Alpine Fault Tours Exposed, Whataroa Picture: Gaunt Creek exposure site - Check out Tripadvisor members' 336 candid photos and videos. Figure 11 Schematic diagram of the dextral-reverse Alpine Fault and its scarp. The rupture will produce one of the biggest earthquakes since European settlement of New Zealand, and it will have a major impact on the lives of many people. Register Warranty. [5] Then uplift slowly began as the plate motion became slightly oblique to the strike of the Alpine Fault. Collision has been active since the Cenozoic and exhumation models predict that surface rocks were buried ~20km in the Pliocene. In this case the mapped fault trace (rupture surface; bold red line) is located near the base of the scarp. Alpine Fault movement. 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