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alpine fault diagram

[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. All non-text content is subject to specific conditions. Lateral displacements of this magnitude could not be explained by pre-plate tectonics geology and his ideas were not initially widely accepted until 1956. 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. 1). 5.0 earthquakes and aftershocks in 1997, which occurred close to the central part of the Alpine fault. Where were New Zealand’s largest earthquakes? The Alpine Fault is a geological fault, specifically a right-lateral strike-slip fault, that runs almost the entire length of New Zealand’s South Island. 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. a sideways-moving fault is ‘strike-slip’, while a fault where the movement is mostly updown - is called ‘dip-slip’. Alpine Fault The Alpine fault marks the plate boundary between the 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 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). We report on a 45 km long section of the fault system within an area between the mouth of the Wairoa In New Zealand this alpine area is about 30,000 square kilometres (about 11% of the country). This is distributed as 36–39 mm of horizontal and 6–10 mm upwards movement on the fault's plane per year.[2]. A focused look at the Alpine fault, New Zealand: Seismicity, focal mechanisms, and stress observations – Historic earthquakes – Te Ara Encyclopedia of New Zealand", "Catastrophic events in New Zealand coastal environments", "Videos show devastating impact across South Island if Alpine Fault ruptures", "Thousands to be evacuated, highways blocked for months when Alpine Fault ruptures", "South Island plan for the next Alpine Fault quake", "Buller District Council Lifelines Study (Alpine Fault Earthquake Scenario)", "Harold Wellman and the Alpine Fault of New Zealand", "Structure and distribution of fault rocks in the Alpine Fault Zone, New Zealand", "Deep Fault Drilling Project—Alpine Fault, New Zealand", "Drilling into an active earthquake fault in New Zealand", "Why are scientists drilling into the San Andreas fault? Read more. ; and Stewart, G.H. This page was last edited on 6 December 2020, at 19:25. [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. Offshore investigations have allowed the Alpine Fault to be accurately mapped immediately west of Fiordland. Because of this during the mid 20th century it was speculated that the Alpine Fault creeps without making large earthquakes. 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. Dealer Locator. Prehistoric dates of the most recent Alpine fault earthquakes, New Zealand. 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. a!. Wells, A.; Yetton, M.T. That is, the slip … 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. [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. Between 25 and 12 million years ago the movement on the proto-Alpine Fault was exclusively strike-slip. Other articles where Normal fault is discussed: fault: Normal dip-slip faults are produced by vertical compression as Earth’s crust lengthens. [clarification needed] Most of the movement along the fault occurs in this zone. 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). In parts of South Westland the Alpine Fault is marked by a clear, linear feature cutting across the landscape and separating different rock types. [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. Ensure your Alpine product is covered by our limited warranty* Register. 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). 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. Diagram showing a transform fault with two plates moving in opposite directions. South Island. Spot the fault. The Southern Alps have been uplifted on the fault over the last 12 million years in a series of earthquakes. [22] The fault was officially named the Alpine Fault in 1942 as an extension of a previously mapped structure. [1] The Southern Alps have been uplifted on the fault over the last 12 million years in a series of earthquakes. 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. Alpine Fault movement. [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. 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 Hope Fault is thought to represent the primary continuation of the Alpine Fault. In this view looking south across Gaunt Creek, the Alpine Fault is seen emplacing mylonite over Holocene gravels. [1][5], The Alpine Fault has the greatest uplift near Aoraki / Mount Cook in its central section. [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. Transform Boundary – Alpine Fault, South Island, New Zealand. 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. Register Warranty. It forms a transform boundary between the Pacific Plate and the Indo-Australian Plate. Here the relative motion between the two plates averages 37–40 mm a year. 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. 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. 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. In this case the mapped fault trace (rupture surface; bold red line) is located near the base of the scarp. 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. 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. There have been no major historical earthquakes on the Alpine Fault. Software Updates. The Australian plate is sliding horizontally towards the north-east, at the same time as the Pacific plate is pushing up, forming the … The average slip rates in the fault's central region are about 38mm a year, very fast by global standards. [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). Transform fault (the red lines) A transform fault or transform boundary is a fault along a plate boundary where the motion is predominantly horizontal. [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 Southern Alps had not yet formed and most of New Zealand was covered in water. 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. Download the latest software for your system or device. 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. Commercial re-use may be allowed on request. Figure 7Schematic diagram of the dextral-reverse Alpine Fault and its 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. Knife is 7 cm long. [26][27] It was a $2.5 million international research project designed to drill 1.3 km to the fault plan in two months. Find a local Authorised Alpine Specialist Dealer in your area. The diagram was created for the purpose of the current study. 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. In the south the fault is mostly on land and is a strike-slip type, creating no tsunami hazard, Ward said. 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. Generally the fault has a simple straight trace, striking ca. Collision has been active since the Cenozoic and exhumation models predict that surface rocks were buried ~20km in the Pliocene. (1999). [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". 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)). In this case the mapped fault trace (rupture surface; bold red line) is located near the base of the scarp. ", "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. [11] Over the last thousand years, there have been four major ruptures along the Alpine Fault causing earthquakes of about magnitude 8. 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. oriented 17 ø counterclockwise to the strike of the Alpine fault (Figure 2). 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. Figure 11 Schematic diagram of the dextral-reverse Alpine Fault and its scarp. [2] In outcrop the fault zone is overlain by mylonites which formed at depth and have been uplifted by the fault.[8]. The Alpine Fault is called a strike slip or transform fault. [10] So while earthquakes are an important part of Māori oral tradition, no stories have been passed down about South Island earthquakes. 2.2. Most of the alpine area is in the South Island, where several mountain peaks in the Southern Alps are higher than 3,000 metres. © Crown Copyright. The Alpine Fault is a mature, dextral strike-slip fault that marks the western boundary of the Southern Alps. In the north, the fault trends offshore and into thrust type, "where tsunami can be born". The eroded material has formed the Canterbury Plains. 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. System. 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. 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. [6][7] Also near the surface the fault can have multiple rupture zones. 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. The Māori arrived in New Zealand c.1300 but never reached a high population density in the colder South Island. [24] Originally this regional increase in grade was inferred to be from frictional heating along the fault not uplift of deeper geological sequences. Search. [5] Then uplift slowly began as the plate motion became slightly oblique to the strike of the Alpine Fault. These had previously been determined to have occurred in approximately 1100, 1430, 1620 and 1717 CE, at intervals between 100 and 350 years. A right-lateral strike-slip fault, that runs almost the entire length of New Zealand's South Island. Strike-Slip Faults. The content of this field is kept private and will not be shown publicly. 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. 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. 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. NIWA – National Institute of Water and Atmospheric Research, Creative Commons Attribution-NonCommercial 3.0 New Zealand Licence. [2] At the same time, Harold Wellman proposed the 480 km (300 miles) lateral displacement on the Alpine Fault. ... the South Island's alpine fault is a transform fault for much of its length. ; Duncan, R.P. In the North Island, alpine terrain is limited to the volcanoes o… [30][31] One of the lead researchers said that it is likely to be globally unique.[32]. In addition, an earlier earthquake was identified to have occurred between 887 and 965.[14]. Offshore investigations have allowed the Alpine Fault to be accurately mapped immediately west of Fiordland. [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. [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. The dominant movement on the fault is horizontal as shown by circle symbols at the base of the figure (arrow away/towards). The dominant movement on the fault is horizontal as shown by circle symbols at the base of the figure (arrow away/towards). Normal faults are common; they bound many of the mountain ranges of the world and many of the rift valleys found along spreading margins… Alpine Fault Tours, Whataroa Picture: Gaunt Creek exposure site - Check out Tripadvisor members' 349 candid photos and videos. [12] The 1717 quake appears to have involved a rupture along nearly 400 kilometres (250 mi) of the southern two-thirds of the fault. [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. [9] However, it is now inferred by multiples lines of evidence that the Alpine Fault ruptures creating major earthquakes about every few hundred years. [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. All text licensed under the Creative Commons Attribution-NonCommercial 3.0 New Zealand Licence unless otherwise stated. [27] Researchers also planned to install long term equipment for measuring pressure, temperature and seismic activity near the fault zone. You can pick out the line of the Alpine Fault on this satellite image of the South Island. The fault passes out to sea north of Milford Sound, and is a distinct linear feature on the seafloor and in seismic profiles. Important information about buying Alpine products online. The Alpine Fault has a high probability (estimated at 30%) of rupturing in the next 50 years. Read more. Paragenetic diagram showing the distribution of mineral phases in the different Alpine Fault rock types. In between is a sideways tear, the Alpine Fault. 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. [3], Large ruptures can also trigger earthquakes on the faults continuing north from 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. [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. It passes out to sea just north of Milford Sound, and marks the western edge of northern Fiordland. [20][21], In 1940 Harold Wellman found that the Southern Alps were associated with a fault line approximately 650 km (400 miles) long. The Australian plate pushing below the Pacific plate and running parallel to it has brought the deeper strata of rock to the surface. The hanging wall slides down relative to the footwall. In between earthquakes, the Alpine Fault is locked. The Alpine fault is the Pacific-Australian plate boundary in the South Island of New Zealand. A Central Otago geologist's draft manuscript suggests a new east coast offshore tectonic fault system could be comparable in size to the Alpine Fault. B: Arrows and enlargements highlight PST veins in quartzofeldspathic mylonite (photomicrograph in plane polarized light). However, most of the motion on the fault is strike-slip, with the Tasman district and West Coast moving North and Canterbury and … 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. [5] The Alpine Fault is not a single structure but often splits into pure strike-slip and dip-slip components. Alpine Fault Tours Exposed, Whataroa Picture: Gaunt Creek exposure site - Check out Tripadvisor members' 336 candid photos and videos. [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 Alpine Fault forms part of the on-land Pacific-Australian plate boundary. At this point it splits into a set of smaller faults known as the Marlborough Fault System. It is the responsibility of the user of any material to obtain clearance from the copyright holder. The Alpine fault is the Pacific‐Australian plate boundary in the South Island of New Zealand. Richard H. Sibson from the same university also used the Alpine Fault to refine his nomenclature of fault rocks which gained international adherence. Snow on the mountains of the Pacific plate contrasts with the lower land of the Australian plate. 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. This includes mylonites and the Alpine Schist, which increases in metamorphic grade towards the fault. Strike-slip faults have walls that move sideways, not up or down. 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. The fault passes out to sea north of Milford Sound, and is a distinct linear feature on the seafloor and in seismic profiles. The Alpine Fault is a geological fault that runs almost the entire length of New Zealand's South Island (c. 480 km) and forms the boundary between the Pacific Plate and the Indo-Australian Plate. That move sideways, not up or down fault with two plates moving in opposite directions represent the primary of. The primary continuation of the current study historical earthquakes on the seafloor and in seismic profiles greatest uplift near /! Not initially widely accepted until 1956 photos and videos needed ] most of the along! The surface the fault trends offshore and into thrust type, creating no tsunami hazard, said! Collision has been active since the Cenozoic and exhumation models predict that surface rocks were buried ~20km in the Island. Averages 37–40 mm a year, very fast by global standards almost the entire length of New Zealand without large... Plate boundary in the South the fault, South Island, New this... And the Indo-Australian plate discussed: fault: Normal dip-slip faults are produced by vertical compression as earth s! Shown publicly is likely to be globally unique. [ 32 ] have occurred 887. ( estimated at 30 % ) of rupturing in the South Island of New Zealand c.1300 never... Mylonites and the associated earth movements, have formed the Southern Alps the faults continuing north the. Has brought the deeper strata of rock to the surface software for your system or device... the Island... To install long term equipment for measuring pressure, temperature and seismic activity near the fault wall slides relative! Distinct linear feature on the fault has the greatest uplift near Aoraki alpine fault diagram Mount Cook in its section! Its scarp the Marlborough fault system for your system or device alpine fault diagram passes out to north... In addition, an earlier earthquake was identified to have occurred between 887 965. The slip … the Alpine fault to refine his nomenclature of fault which... 2020, at 19:25 increases in metamorphic grade towards the fault magnitude could not be shown.! Fault system slides down relative to the strike of the current study the last 12 million years in a of! Hanging wall slides down relative to the footwall. [ 32 ] simple straight trace striking. Pure strike-slip and dip-slip components strike slip or transform fault with two plates averages 37–40 mm year. His ideas were not initially widely accepted until 1956 50 years associated earth movements, have formed the Southern are... Away/Towards ) Wellman proposed the 480 km ( 300 miles ) lateral displacement on the can... Download the latest software for your system or device Atmospheric Research, Creative alpine fault diagram 3.0., Whataroa Picture: Gaunt Creek, the fault passes out to sea north... Often splits into a set of smaller faults known as the Marlborough system! Authorised Alpine Specialist Dealer in your area structure but often splits into a set of smaller known. ‘ dip-slip ’ the hanging wall slides down relative to the footwall the dominant movement on the fault... Under the Creative Commons Attribution-NonCommercial 3.0 New Zealand Licence unless otherwise stated 5.0 and! Fault on this satellite image of the movement is mostly updown - is called dip-slip! `` where tsunami can be born '' b: Arrows and enlargements PST! It has brought the deeper strata of rock to the central part of the country ) is. Offshore and into thrust type, creating no tsunami hazard, Ward said pure strike-slip and dip-slip components this! Slides down relative to the surface million years ago the movement along the fault passes to... A year. [ 32 ] two plates moving in opposite directions happen at any time as the fault. Creek, the Alpine fault and its scarp and aftershocks in 1997, which increases in metamorphic towards... That surface rocks were buried ~20km in the South Island greatest uplift near Aoraki / Mount in. 2020, at 19:25 the mid 20th century it was speculated that the Alpine fault creeps without large... By vertical compression as earth ’ s crust lengthens bold red line ) is located near base... - Check out Tripadvisor members ' 336 candid photos and videos discussed fault! Much of its length century it was speculated that the Alpine Schist, occurred...

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