There have been no major historical earthquakes on the Alpine Fault. a!. 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. Lateral displacements of this magnitude could not be explained by pre-plate tectonics geology and his ideas were not initially widely accepted until 1956. In between earthquakes, the Alpine Fault is locked. [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. 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. © Crown Copyright. 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. 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 this case the mapped fault trace (rupture surface; bold red line) is located near the base of the scarp. The fault passes out to sea north of Milford Sound, and is a distinct linear feature on the seafloor and in seismic profiles. [24] Originally this regional increase in grade was inferred to be from frictional heating along the fault not uplift of deeper geological sequences. ; and Stewart, G.H. Alpine Fault movement. [30][31] One of the lead researchers said that it is likely to be globally unique.[32]. 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. This page was last edited on 6 December 2020, at 19:25. The Australian plate is sliding horizontally towards the north-east, at the same time as the Pacific plate is pushing up, forming the … 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. Download the latest software for your system or device. Our new data set defines the depth of the base of the seismogenic zone throughout the central South Island and provides precise locations and focal mechanisms for tectonic and stress analysis. [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. 1). [15] In 2017, GNS researchers revised the figures after they combined updated Hokuri site records with a thousand-year record from another site 20 km away at John O'Groats River to produce a record of 27 major earthquake events during the 8000-year period. 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. Because of this during the mid 20th century it was speculated that the Alpine Fault creeps without making large earthquakes. This displacement was inferred by Wellman due in part to the similarity of rocks in Southland and Nelson on either side of the Alpine Fault. Knife is 7 cm long. 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. Register Warranty. In the middle the Alpine Fault is a transform boundary and has both dextral (right-lateral) strike-slip movement and uplift on the southeastern side. [2] In outcrop the fault zone is overlain by mylonites which formed at depth and have been uplifted by the fault.[8]. [1] The Southern Alps have been uplifted on the fault over the last 12 million years in a series of 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. Generally the fault has a simple straight trace, striking ca. 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. In the south the fault is mostly on land and is a strike-slip type, creating no tsunami hazard, Ward said. 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. Through the South Island the Alpine Fault acts as a transfer of plate convergence to east facing subduction of the Australian plate beneath the Pacific plate, occurring south of New Zealand in the Puysegur trench. It passes out to sea just north of Milford Sound, and marks the western edge of northern Fiordland. Spot the fault. B: Arrows and enlargements highlight PST veins in quartzofeldspathic mylonite (photomicrograph in plane polarized light). In the north, the fault trends offshore and into thrust type, "where tsunami can be born". The Hope Fault is thought to represent the primary continuation of the Alpine Fault. The Alpine fault is the Pacific-Australian plate boundary in the South Island of New Zealand. NIWA – National Institute of Water and Atmospheric Research, Creative Commons Attribution-NonCommercial 3.0 New Zealand Licence. [2], The fault zone is exposed at numerous locations along the West Coast and typically comprises a 10-50 m wide fault gouge zone with pervasive hydrothermal alteration. [22] The fault was officially named the Alpine Fault in 1942 as an extension of a previously mapped structure. Ensure your Alpine product is covered by our limited warranty* Register. You can pick out the line of the Alpine Fault on this satellite image of the South Island. South Island. Search. It is the responsibility of the user of any material to obtain clearance from the copyright holder. [1][3], The Pacific Plate and Indo-Australian Plate boundary forms the Macquarie Fault Zone in the Puysegur Trench off the southwestern corner of the South Island and comes onshore as the Alpine Fault just north of Milford Sound. Find a local Authorised Alpine Specialist Dealer in your area. [2] At the same time, Harold Wellman proposed the 480 km (300 miles) lateral displacement on the Alpine Fault. [29], In 2017 they reported they had discovered beneath Whataroa, a small township on the Alpine Fault, "extreme" hydrothermal activity which "could be commercially very significant". The Alpine Fault has a high probability (estimated at 30%) of rupturing in the next 50 years. The dominant movement on the fault is horizontal as shown by circle symbols at the base of the figure (arrow away/towards). [9] However, it is now inferred by multiples lines of evidence that the Alpine Fault ruptures creating major earthquakes about every few hundred years. Other articles where Normal fault is discussed: fault: Normal dip-slip faults are produced by vertical compression as Earth’s crust lengthens. [1][5], The Alpine Fault has the greatest uplift near Aoraki / Mount Cook in its central section. This includes mylonites and the Alpine Schist, which increases in metamorphic grade towards the fault. ; Duncan, R.P. (1999). Commercial re-use may be allowed on request. [2] The last major earthquake on the Alpine Fault was in c. 1717 AD, the probability of another one occurring within the next 50 years is estimated at about 30 percent. Offshore investigations have allowed the Alpine Fault to be accurately mapped immediately west of Fiordland. oriented 17 ø counterclockwise to the strike of the Alpine fault (Figure 2). Diagram showing a transform fault with two plates moving in opposite directions. Important information about buying Alpine products online. Here the relative motion between the two plates averages 37–40 mm a year. Movement along the Alpine Fault is deforming the microcontinent of, Pacific Plate and Indo-Australian Plate boundary, Australian Nuclear Science and Technology Organisation, "Alpine Fault / Major Faults in New Zealand / Earthquakes / Science Topics / Learning / Home – GNS Science", "New study says Alpine Fault quake interval shorter than thought: GNS Science", "Timing of late Holocene surface rupture of the Wairau Fault, Marlborough, New Zealand", 10.1130/0016-7606(1995)107<0231:OOSSSA>2.3.CO;2, "An extremely low-density human population exterminated New Zealand moa", "1. 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. Strike-slip faults have walls that move sideways, not up or down. The eroded material has formed the Canterbury Plains. [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. 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. [12] The 1717 quake appears to have involved a rupture along nearly 400 kilometres (250 mi) of the southern two-thirds of the fault. 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. 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. [13] Newer research carried out by the University of Otago and the Australian Nuclear Science and Technology Organisation revised the dates of the pre-1717 earthquakes to between 1535 and 1596 (instead of 1620), 1374 and 1405 (instead of 1430), and 1064 and 1120 (instead of 1100). Metamorphic grades in the hanging-wall Alpine Schist and a typical fault rock assemblage (modified from Toy et al., 2011) are indicated, as is the location of the pseudotachylyte (PST) in an outcrop at the Little Man River illustrated in B. 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). In the North Island, alpine terrain is limited to the volcanoes o… At this point it splits into a set of smaller faults known as the Marlborough Fault System. 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. This gave a mean recurrence rate of 291 years, plus or minus 23 years, down from the previously estimated rate of 329 years, plus or minus 26 years. Figure 7Schematic diagram of the dextral-reverse Alpine Fault and its scarp. Normal faults are common; they bound many of the mountain ranges of the world and many of the rift valleys found along spreading margins… In parts of South Westland the Alpine Fault is marked by a clear, linear feature cutting across the landscape and separating different rock types. There is paleotsunami evidence of near-simultaneous ruptures of the Alpine Fault and Wellington (and/or other major) faults to the North having occurred at least twice in the past 1,000 years. These had previously been determined to have occurred in approximately 1100, 1430, 1620 and 1717 CE, at intervals between 100 and 350 years. This set of faults, which includes the Wairau Fault, the Hope Fault, the Awatere Fault, and the Clarence Fault, transfer displacement between the Alpine Fault and the Hikurangi subduction zone to the north. 5.0 earthquakes and aftershocks in 1997, which occurred close to the central part 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. All non-text content is subject to specific conditions. The Alpine Fault is called a strike slip or transform fault. Read more. A right-lateral strike-slip fault, that runs almost the entire length of New Zealand's South Island. [clarification needed] Most of the movement along the fault occurs in this zone. [5] The Alpine Fault is not a single structure but often splits into pure strike-slip and dip-slip components. 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. [25], The Deep Fault Drilling Project (DFDP) was an attempt in 2014 to retrieve rock and fluid samples and make geophysical measurements inside the Alpine Fault zone at depth. [27] The DFDP was the second project to try to drill an active fault zone and return samples after the San Andreas Fault Observatory at Depth. The content of this field is kept private and will not be shown publicly. Snow on the mountains of the Pacific plate contrasts with the lower land of the Australian plate. [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. Scientists say that a similar earthquake could happen at any time as the interval since 1717 is longer than between the earlier events. [26][27] It was a $2.5 million international research project designed to drill 1.3 km to the fault plan in two months. Richard H. Sibson from the same university also used the Alpine Fault to refine his nomenclature of fault rocks which gained international adherence. The Southern Alps had not yet formed and most of New Zealand was covered in water. This is distributed as 36–39 mm of horizontal and 6–10 mm upwards movement on the fault's plane per year.[2]. The Australian plate pushing below the Pacific plate and running parallel to it has brought the deeper strata of rock to the surface. In the last 12 million years the Southern Alps have been uplifted approximately 20 kilometres, however, as this has occurred more rain has been trapped by the mountains leading to more erosion. All text licensed under the Creative Commons Attribution-NonCommercial 3.0 New Zealand Licence unless otherwise stated. The Alpine Fault forms part of the on-land Pacific-Australian plate boundary. The Māori arrived in New Zealand c.1300 but never reached a high population density in the colder South Island. [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. Earthquakes along the fault, and the associated earth movements, have formed the Southern Alps. 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. In this view looking south across Gaunt Creek, the Alpine Fault is seen emplacing mylonite over Holocene gravels. ", "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. The average slip rates in the fault's central region are about 38mm a year, very fast by global standards. [23] Wellman also proposed in 1964 that the Alpine Fault was a Cenozoic structure, which was in conflict with the older Mesozoic age accepted at the time. It forms a transform boundary between the Pacific Plate and the Indo-Australian Plate. [10] So while earthquakes are an important part of Māori oral tradition, no stories have been passed down about South Island earthquakes. a sideways-moving fault is ‘strike-slip’, while a fault where the movement is mostly updown - is called ‘dip-slip’. That is, the slip … The Southern Alps have been uplifted on the fault over the last 12 million years in a series of earthquakes. Software Updates. The Alpine Schist is located on the eastern margin of the Alpine Fault, which accommodates oblique collision between the Pacific and Australian plates in New Zealand. A focused look at the Alpine fault, New Zealand: Seismicity, focal mechanisms, and stress observations Alpine Fault Tours, Whataroa Picture: Gaunt Creek exposure site - Check out Tripadvisor members' 349 candid photos and videos. Paragenetic diagram showing the distribution of mineral phases in the different Alpine Fault rock types. The Alpine fault is the Pacific‐Australian plate boundary in the South Island of New Zealand. In this case the mapped fault trace (rupture surface; bold red line) is located near the base of the scarp. [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. Alpine Fault The Alpine fault marks the plate boundary between the The Alpine Fault is a mature, dextral strike-slip fault that marks the western boundary of the Southern Alps. Until 1956 activity near the fault passes out to sea north of Milford Sound, and is distinct. Mm of horizontal and 6–10 mm upwards movement on the Alpine fault, Harold proposed! At the base of the Pacific plate and running parallel to it has brought the deeper strata of to. [ clarification needed ] most of the figure ( arrow away/towards ) lateral displacement on the fault... Are produced by vertical compression as earth ’ s crust lengthens exhumation predict. 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