That is, the slip … Figure 7Schematic diagram of the dextral-reverse Alpine Fault and its scarp. 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. 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. 5.0 earthquakes and aftershocks in 1997, which occurred close to the central part of the Alpine fault. In between is a sideways tear, the Alpine Fault. ; Duncan, R.P. Generally the fault has a simple straight trace, striking ca. 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. NIWA – National Institute of Water and Atmospheric Research, Creative Commons Attribution-NonCommercial 3.0 New Zealand Licence. Because of this during the mid 20th century it was speculated that the Alpine Fault creeps without making large earthquakes. [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. The Southern Alps have been uplifted on the fault over the last 12 million years in a series of earthquakes. [2] At the same time, Harold Wellman proposed the 480 km (300 miles) lateral displacement on the Alpine Fault. [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. It passes out to sea just north of Milford Sound, and marks the western edge of northern Fiordland. [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. Ensure your Alpine product is covered by our limited warranty* Register. 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 has a high probability (estimated at 30%) of rupturing in the next 50 years. [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. Wells, A.; Yetton, M.T. 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 the Pacific-Australian plate boundary in the South Island of New Zealand. Paragenetic diagram showing the distribution of mineral phases in the different Alpine Fault rock types. Strike-Slip Faults. The average slip rates in the fault's central region are about 38mm a year, very fast by global standards. In parts of South Westland the Alpine Fault is marked by a clear, linear feature cutting across the landscape and separating different rock types. The Hope Fault is thought to represent the primary continuation of the Alpine Fault. a!. [3], Large ruptures can also trigger earthquakes on the faults continuing north from the Alpine Fault. 2.2. Prehistoric dates of the most recent Alpine fault earthquakes, New Zealand. It forms a transform boundary between the Pacific Plate and the Indo-Australian Plate. Important information about buying Alpine products online. 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. Normal faults are common; they bound many of the mountain ranges of the world and many of the rift valleys found along spreading margins… Scientists say that a similar earthquake could happen at any time as the interval since 1717 is longer than between the earlier events. [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. Offshore investigations have allowed the Alpine Fault to be accurately mapped immediately west of Fiordland. [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. © Crown Copyright. 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. [20][21], In 1940 Harold Wellman found that the Southern Alps were associated with a fault line approximately 650 km (400 miles) long. 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. 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. Strike-slip faults have walls that move sideways, not up or down. ... the South Island's alpine fault is a transform fault for much of its length. In this view looking south across Gaunt Creek, the Alpine Fault is seen emplacing mylonite over Holocene gravels. [6][7] Also near the surface the fault can have multiple rupture zones. You can pick out the line of the Alpine Fault on this satellite image of the South Island. Transform fault (the red lines) A transform fault or transform boundary is a fault along a plate boundary where the motion is predominantly horizontal. The content of this field is kept private and will not be shown publicly. 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)). 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. 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 between earthquakes, the Alpine Fault is locked. In addition, an earlier earthquake was identified to have occurred between 887 and 965.[14]. [1][5], The Alpine Fault has the greatest uplift near Aoraki / Mount Cook in its central section. The Australian plate pushing below the Pacific plate and running parallel to it has brought the deeper strata of rock to the surface. Search. The Australian plate is sliding horizontally towards the north-east, at the same time as the Pacific plate is pushing up, forming the … Snow on the mountains of the Pacific plate contrasts with the lower land of the Australian plate. Here the relative motion between the two plates averages 37–40 mm a year. The diagram was created for the purpose of the current study. [5] Then uplift slowly began as the plate motion became slightly oblique to the strike of the Alpine Fault. [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. At this point it splits into a set of smaller faults known as the Marlborough Fault System. His ideas were not initially widely accepted until 1956 case the mapped fault trace rupture! Same university also used the Alpine fault and its scarp for much of its.... [ 32 ] the dominant movement on the mountains of the Alpine fault last edited on December... Measuring pressure, temperature and seismic activity near the surface are produced vertical... 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