The content of this field is kept private and will not be shown publicly. 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. [2] In outcrop the fault zone is overlain by mylonites which formed at depth and have been uplifted by the fault.[8]. [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. A right-lateral strike-slip fault, that runs almost the entire length of New Zealand's South Island. (1999). That is, the slip … Most of the alpine area is in the South Island, where several mountain peaks in the Southern Alps are higher than 3,000 metres. [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. [12] The 1717 quake appears to have involved a rupture along nearly 400 kilometres (250 mi) of the southern two-thirds of the fault. These had previously been determined to have occurred in approximately 1100, 1430, 1620 and 1717 CE, at intervals between 100 and 350 years. 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. Alpine Fault Tours, Whataroa Picture: Gaunt Creek exposure site - Check out Tripadvisor members' 349 candid photos and videos. [9] However, it is now inferred by multiples lines of evidence that the Alpine Fault ruptures creating major earthquakes about every few hundred years. In between earthquakes, the Alpine Fault is locked. [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. In this view looking south across Gaunt Creek, the Alpine Fault is seen emplacing mylonite over Holocene gravels. 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. The Australian plate is sliding horizontally towards the north-east, at the same time as the Pacific plate is pushing up, forming the … [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. This page was last edited on 6 December 2020, at 19:25. [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. Generally the fault has a simple straight trace, striking ca. B: Arrows and enlargements highlight PST veins in quartzofeldspathic mylonite (photomicrograph in plane polarized light). [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. This includes mylonites and the Alpine Schist, which increases in metamorphic grade towards the fault. 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. It is the responsibility of the user of any material to obtain clearance from the copyright holder. Ensure your Alpine product is covered by our limited warranty* Register. NIWA – National Institute of Water and Atmospheric Research, Creative Commons Attribution-NonCommercial 3.0 New Zealand Licence. The Southern Alps had not yet formed and most of New Zealand was covered in water. The Alpine Fault is a mature, dextral strike-slip fault that marks the western boundary of the Southern Alps. In parts of South Westland the Alpine Fault is marked by a clear, linear feature cutting across the landscape and separating different rock types. 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. Paragenetic diagram showing the distribution of mineral phases in the different Alpine Fault rock types. System. We report on a 45 km long section of the fault system within an area between the mouth of the Wairoa In the North Island, alpine terrain is limited to the volcanoes o… Where were New Zealand’s largest earthquakes? Strike-slip faults have walls that move sideways, not up or down. [24] Originally this regional increase in grade was inferred to be from frictional heating along the fault not uplift of deeper geological sequences. At this point it splits into a set of smaller faults known as the Marlborough Fault System. The diagram was created for the purpose of the current study. 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. 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. 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. Transform Boundary – Alpine Fault, South Island, New Zealand. 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. Commercial re-use may be allowed on request. Figure 7Schematic diagram of the dextral-reverse Alpine Fault and its scarp. [22] The fault was officially named the Alpine Fault in 1942 as an extension of a previously mapped structure. Here the relative motion between the two plates averages 37–40 mm a year. The Māori arrived in New Zealand c.1300 but never reached a high population density in the colder South Island. Alpine Fault movement. Important information about buying Alpine products online. The fault passes out to sea north of Milford Sound, and is a distinct linear feature on the seafloor and in seismic profiles. Offshore investigations have allowed the Alpine Fault to be accurately mapped immediately west of Fiordland. 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. 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. [20][21], In 1940 Harold Wellman found that the Southern Alps were associated with a fault line approximately 650 km (400 miles) long. 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). Diagram showing a transform fault with two plates moving in opposite directions. 1). 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. 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. Richard H. Sibson from the same university also used the Alpine Fault to refine his nomenclature of fault rocks which gained international adherence. The Alpine fault is the Pacific-Australian plate boundary in the South Island of New Zealand. The dominant movement on the fault is horizontal as shown by circle symbols at the base of the figure (arrow away/towards). In the south the fault is mostly on land and is a strike-slip type, creating no tsunami hazard, Ward said. 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. It forms a transform boundary between the Pacific Plate and the Indo-Australian Plate. In addition, an earlier earthquake was identified to have occurred between 887 and 965.[14]. In New Zealand this alpine area is about 30,000 square kilometres (about 11% of the country). 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 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. 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. [26][27] It was a $2.5 million international research project designed to drill 1.3 km to the fault plan in two months. [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). Because of this during the mid 20th century it was speculated that the Alpine Fault creeps without making large earthquakes. 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. [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. 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. Search. [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. In between is a sideways tear, the Alpine Fault. Earthquakes along the fault, and the associated earth movements, have formed the Southern Alps. 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 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. ; and Stewart, G.H. It passes out to sea just north of Milford Sound, and marks the western edge of northern Fiordland. [10] So while earthquakes are an important part of Māori oral tradition, no stories have been passed down about South Island earthquakes. Dealer Locator. 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 text licensed under the Creative Commons Attribution-NonCommercial 3.0 New Zealand Licence unless otherwise stated. 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. [11] Over the last thousand years, there have been four major ruptures along the Alpine Fault causing earthquakes of about magnitude 8. In this case the mapped fault trace (rupture surface; bold red line) is located near the base of the scarp. The Hope Fault is thought to represent the primary continuation of the Alpine Fault. 5.0 earthquakes and aftershocks in 1997, which occurred close to the central part of the Alpine fault. Read more. South Island. The Alpine Fault has a high probability (estimated at 30%) of rupturing in the next 50 years. Knife is 7 cm long. Snow on the mountains of the Pacific plate contrasts with the lower land of the Australian plate. This is distributed as 36–39 mm of horizontal and 6–10 mm upwards movement on the fault's plane per year.[2]. 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. Strike-Slip Faults. The Southern Alps have been uplifted on the fault over the last 12 million years in a series of earthquakes. 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). The Alpine Fault is called a strike slip or transform fault. Read more. 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