115-538: The Alpine Fault is a geological fault that runs almost the entire length of New Zealand's South Island , being about 600 km (370 mi). long, and forms the boundary between the Pacific plate and the Australian plate . The Southern Alps have been uplifted on the fault over the last 12 million years in a series of earthquakes. However, most of the motion on the fault is strike-slip (side to side), with
230-478: A Mercalli intensity of VIII (significant property damage, loss of life possible) could recur on average in the Christchurch area every 55 years. The study also highlighted the dangers of soil liquefaction of the alluvial sediments underlying the city, and the likelihood of significant damage to water, sewer and power supply services. Geologists have recognised about 100 faults and fault segments in
345-498: A curfew was established for parts of Christchurch Central City from 7 pm to 7 am in response to the earthquake. The New Zealand Army was deployed to the worst affected areas in Canterbury . Insurance claims totalled between NZ$ 2.75 and $ 3.5 billion, although it is unclear how much cost can be attributed to each of the earthquake events in the 2010–2011 Canterbury earthquake sequence. The total estimated damage bill
460-405: A decollement . Extensional decollements can grow to great dimensions and form detachment faults , which are low-angle normal faults with regional tectonic significance. Due to the curvature of the fault plane, the horizontal extensional displacement on a listric fault implies a geometric "gap" between the hanging and footwalls of the fault forms when the slip motion occurs. To accommodate into
575-860: A plate boundary. This class is related to an offset in a spreading center , such as a mid-ocean ridge , or, less common, within continental lithosphere , such as the Dead Sea Transform in the Middle East or the Alpine Fault in New Zealand. Transform faults are also referred to as "conservative" plate boundaries since the lithosphere is neither created nor destroyed. Dip-slip faults can be either normal (" extensional ") or reverse . The terminology of "normal" and "reverse" comes from coal mining in England, where normal faults are
690-513: A Saturday were born at Christchurch Women's Hospital in the twenty-four hours after the quake, with the first baby arriving six minutes after the initial shock. This was at least in part due to outlying birthing centres being closed, pending structural checks, forcing more mothers to deliver at hospitals than was generally the case. The quake's epicentre was around Darfield , around 40 kilometres (25 mi) from Christchurch. Four metres (13 ft) of sideways movement has been measured between
805-460: A boil water notice remained in effect for parts of Waimakariri District until 19 September. A 5 km (3.1 mi) section of rail track was damaged near Kaiapoi and there was lesser track damage at Rolleston and near Belfast . As a precaution, state rail operator KiwiRail shut down the entire South Island rail network after the earthquake, halting some 15 trains. Two locomotives running light (i.e. without any carriages or wagons) came to
920-515: A complex splaying of faults, which is associated with large earthquakes adjacent to, but off the Alpine fault itself, such the 1929 Murchison earthquake , 1968 Inangahua earthquake and 1929 Arthur's Pass earthquake . The Alpine Fault has the greatest uplift of the Pacific plate near Aoraki / Mount Cook in its central section. Here the relative motion between the two plates averages 37–40 mm
1035-582: A fault hosting valuable porphyry copper deposits is northern Chile's Domeyko Fault with deposits at Chuquicamata , Collahuasi , El Abra , El Salvador , La Escondida and Potrerillos . Further south in Chile Los Bronces and El Teniente porphyry copper deposit lie each at the intersection of two fault systems. Faults may not always act as conduits to surface. It has been proposed that deep-seated "misoriented" faults may instead be zones where magmas forming porphyry copper stagnate achieving
1150-500: A fault is locked, and when it reaches a level that exceeds the strength threshold, the fault ruptures and the accumulated strain energy is released in part as seismic waves , forming an earthquake . Strain occurs accumulatively or instantaneously, depending on the liquid state of the rock; the ductile lower crust and mantle accumulate deformation gradually via shearing , whereas the brittle upper crust reacts by fracture – instantaneous stress release – resulting in motion along
1265-410: A fault often forms a discontinuity that may have a large influence on the mechanical behavior (strength, deformation, etc.) of soil and rock masses in, for example, tunnel , foundation , or slope construction. The level of a fault's activity can be critical for (1) locating buildings, tanks, and pipelines and (2) assessing the seismic shaking and tsunami hazard to infrastructure and people in
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#17327659055731380-476: A fault rupture". The February 2011 Christchurch earthquake experienced PGA of 1.51 g . GNS seismologists and geophysicists, who believed the 7.1 M w quake consisted of three or four separate quakes, quickly proposed at least two models for the quake. John Beavan proposed a four-fault model consisting of a 6.5 M w quake on the Charing Cross fault, followed by a 7.0 M w quake on
1495-408: A fault's age by studying soil features seen in shallow excavations and geomorphology seen in aerial photographs. Subsurface clues include shears and their relationships to carbonate nodules , eroded clay, and iron oxide mineralization, in the case of older soil, and lack of such signs in the case of younger soil. Radiocarbon dating of organic material buried next to or over a fault shear
1610-486: A fund to help repair historic buildings damaged by the quake. The Government allocated NZ$ 10 million towards restoration of such buildings a few days later. A feature of the quake was the damage caused by soil liquefaction . This was particularly the case in the riverside areas of Avonside , Dallington , Burwood , Avondale , and Kaiapoi , and in river delta areas near Bexley , Brooklands , Spencerville , Pines Beach , and Kairaki , with other areas being affected to
1725-473: A gigabyte of data per minute. 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. It was a $ 2.5 million international research project designed to drill 1.3 km to the fault plan in two months. The DFDP was the second project to try to drill an active fault zone and return samples after
1840-471: A high population density in the colder South Island. Therefore, while earthquakes are an important part of Māori oral tradition, no stories have been passed down about South Island earthquakes. Over the last thousand years, the major ruptures along the Alpine Fault, causing earthquakes of about magnitude 8 had previously been determined to have occurred at least four times. These had separation of between 100 and 350 years. The 1717 quake appeared to have involved
1955-481: A result of rock-mass movements. Large faults within Earth 's crust result from the action of plate tectonic forces, with the largest forming the boundaries between the plates, such as the megathrust faults of subduction zones or transform faults . Energy release associated with rapid movement on active faults is the cause of most earthquakes . Faults may also displace slowly, by aseismic creep . A fault plane
2070-545: A rupture along nearly 400 kilometres (250 mi) of the southern two-thirds of the fault. Scientists say that a similar earthquake could happen at any time, as the interval since 1717 is longer than the intervals between the earlier events. Newer research carried out by the University of Otago , the Australian Nuclear Science and Technology Organisation and others has revised the dates and nature of
2185-572: A stop just 30 metres short of a major buckle in the line. After inspection, services south of Dunedin and north of Kaikōura recommenced at 10:30 am that day. The Main South Line , linking Christchurch with Dunedin, was given the all-clear and reopened, albeit with a 40 km/h speed restriction north of Ashburton, just after 6 pm to allow emergency aid, including 300,000 litres (70,000 imp gal; 80,000 US gal) of drinking water, to be railed into Christchurch. By
2300-410: A substantially lesser degree or not at all. Damage from liquefaction may have been worsened by the high water table from a wet winter. Liquefaction can also cause buried pipes to float up to the surface. This has caused problems for the gravity-fed sewer system, which may need to be completely rebuilt in some areas. While the problem had long been well understood by planners, it is not clear that
2415-466: A year. This is distributed as 36–39 mm of horizontal and 6–10 mm upwards movement on the fault's plane per year. At the southern end of the fault there is effectively no uplift component of the Pacific plate and other faults share the strain as a result of the plate collision. These include in Fiordland faults associated with the 2003 Fiordland earthquake and 2009 Dusky Sound earthquake ,
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#17327659055732530-448: Is also fair evidence for a post 1717 event confined to North Westland section of the fault but the date is unclear. There are two modes of large earthquake behaviour with either major (M W 7–8) or great (M W > 8) earthquakes and predicting the next mode is a challenge as these appear to evolve over multiple seismic cycles in response to along-strike differences in geometry. Māori arrived in New Zealand about 1300 but never reached
2645-530: Is in the process of again separating from 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. 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. The uplift is due to an element of convergence between
2760-543: Is often critical in distinguishing active from inactive faults. From such relationships, paleoseismologists can estimate the sizes of past earthquakes over the past several hundred years, and develop rough projections of future fault activity. Many ore deposits lie on or are associated with faults. This is because the fractured rock associated with fault zones allow for magma ascent or the circulation of mineral-bearing fluids. Intersections of near-vertical faults are often locations of significant ore deposits. An example of
2875-406: Is summarised in the following timeline for the various sections of the fault. This work suggests that large fault ruptures occurred in 1717, about 1400, about 1100 and about 390 CE. 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 earthquake terms,
2990-444: Is the plane that represents the fracture surface of a fault. A fault trace or fault line is a place where the fault can be seen or mapped on the surface. A fault trace is also the line commonly plotted on geologic maps to represent a fault. A fault zone is a cluster of parallel faults. However, the term is also used for the zone of crushed rock along a single fault. Prolonged motion along closely spaced faults can blur
3105-464: The 1848 Marlborough earthquake and the 1855 Wairarapa earthquake , both of which badly affected Wellington. These led to formal standards after the 1931 Hawke's Bay earthquake , which have since been progressively updated. By contrast, Haiti's much lower standard codes were poorly enforced and many buildings were made of hand-made non-reinforced concrete, which is extremely vulnerable to seismic damage. Ground shaking in populated areas of Canterbury
3220-536: The 1931 Hawke's Bay earthquake cost NZ£ 7 million, equal to approximately $ 650 million in 2010 dollars. Reports of the quake's intensity in Christchurch generally ranged from V to VIII ( Moderate to Severe ) on the Modified Mercalli Intensity Scale . A strong smell of sulphur was widely reported in Christchurch following the earthquake. Sewers were damaged, and water lines were broken. The water supply at Rolleston, located to
3335-588: The 1989 San Francisco quake , which killed 63 people and was magnitude 7.1 also. The analysis especially compared the Canterbury quake with the 2010 Haiti earthquake , which also occurred in similar proximity to an urban area, also occurred at shallow depth under the surface, and was of very similar strength. Unlike the many tens of thousands of deaths in Haiti (with some estimates placing the death toll at one in ten or higher), only two deaths directly attributable to
3450-604: The Canterbury Plains . The Alpine Fault is not a single structure but often splits into pure strike-slip and dip-slip components. Near the surface, the fault can have multiple rupture zones. The fault zone is exposed at numerous locations along the West Coast, and typically consists of a 10 to 50 m wide fault gouge zone with pervasive hydrothermal alteration. This last is because water penetrates down to up to 6 km (3.7 mi) through hot rock associated with
3565-463: The Chesapeake Bay impact crater . Ring faults are the result of a series of overlapping normal faults, forming a circular outline. Fractures created by ring faults may be filled by ring dikes . Synthetic and antithetic are terms used to describe minor faults associated with a major fault. Synthetic faults dip in the same direction as the major fault while the antithetic faults dip in
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3680-582: The Mercalli intensity scale . Some damaging aftershocks followed the main event, the strongest of which was a magnitude 6.3 shock known as the Christchurch earthquake that occurred nearly six months later on 22 February 2011. Because this aftershock was centred very close to Christchurch, it was much more destructive and resulted in the deaths of 185 people. The earthquake on 4 September caused widespread damage and several power outages, particularly in
3795-581: The Otago fault system , in Canterbury faults such as the Ostler Fault Zone and those associated with the 7.1 M W Darfield earthquake . The uplift in this South Westland region of the fault which has a dextral strike-slip rate of about 28 mm (1.1 in)/year is on the Australian plate side of it with meter scale vertical uplift every 290 years odd. Between 25 and 12 million years ago
3910-559: The San Andreas Fault Observatory at Depth . One of the goals of the project was to use the deformed rocks from the fault zone to determine its resistance to stress. Researchers also planned to install long term equipment for measuring pressure, temperature and seismic activity near the fault zone. 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,
4025-565: The Southern Alps were associated with a fault line approximately 650 km (400 miles) long. The fault was officially named the Alpine Fault in 1942 as an extension of a previously mapped structure. At the same time, Harold Wellman proposed the 480 kilometres (300 mi) lateral displacement on the Alpine Fault. This displacement was inferred by Wellman due in part to the similarity of rocks in Southland and Nelson on either side of
4140-459: The Tasman district and West Coast moving north and Canterbury and Otago moving south. The average slip rates in the fault's central region are about 38 mm (1.5 in) a year, very fast by global standards. The last major earthquake on the Alpine Fault was in about 1717 AD with a great earthquake magnitude of M w 8.1± 0.1. The probability of another one occurring before 2068
4255-439: The University of Canterbury and Lincoln University , and the Christchurch campus of the University of Otago were also closed until 13 September awaiting health and safety assessments. Crime in Christchurch decreased eleven percent compared with the previous year following the earthquake, although there were initial reports of looting in the city centre and "known criminals" trying to pass off as council workers to get into
4370-422: The 8000-year period. This gave a mean recurrence rate of 291 years, plus or minus 23 years, versus the previously estimated rate of 329 years, plus or minus 26 years. In the new study, the interval between earthquakes ranged from 160 to 350 years, and the probability of an earthquake occurring in the 50 years following 2017 was estimated at 29 percent for this southern sector of the fault alone. A 2021 study estimated
4485-522: The Alpine Fault could lead to roads (particularly in or to the West Coast) being blocked for months, as with the 2016 Kaikōura earthquake , with problems in supplying towns and evacuating tourists. District councils along the West Coast and in Canterbury have commissioned studies and begun preparations for an anticipated large earthquake on the Alpine Fault. In 1940, Harold Wellman found that
4600-487: The Alpine Fault to the southwest of Fiordland examined the Dagg Basin, an offshore sedimentary basin at 3,000 m (9,800 ft) depth. Basin sediments are primarily from Pleistocene glaciation , and structures within them reveal a past complexity that is no longer present in the basin. The current structure is a pull-apart basin along a releasing bend in the Alpine Fault, with a segment of inverted basin along
4715-436: The Alpine Fault. Because of this, during the mid-20th century it was speculated that the Alpine Fault creeps without making large earthquakes. However, it is now inferred by multiples lines of evidence that the Alpine Fault ruptures, creating major earthquakes approximately every few hundred years. The last whole fault rupture event was in 1717 and is now known to have been a great earthquake of M w 8.1± 0.1. There
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4830-409: The Alpine Fault. Lateral displacements of this magnitude could not be explained by pre-plate tectonics geology and his ideas were not initially widely accepted until 1956. 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 idea coupled with the displacement on the fault proposed that the earth's surface
4945-463: 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. 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. Originally this regional increase in grade
5060-552: The Greendale Fault, and a 6.2 M w quake near Hororata, with a 6.5 M w quake on the fourth fault, which could run between West Melton, Sandy Knolls and Burnham. Caroline Holden proposed a three-fault model, consisting of a 6.3 M w quake of 2–4 seconds on the Charing Cross fault, followed by a 6.9 M w quake lasting 7–18 seconds on the Greendale Fault, and an approximately 6.5 M w quake of 15–18 seconds near Hororata. Ultimately,
5175-535: The New Zealand Treasury. Another projection of the cost covered by insurance (including EQC) was lower at $ 2.1 billion to $ 3.5 billion, but would still rank the quake as the world's fifth most costly to insurers. The Earthquake Commission covers only domestic residences with private insurance and does not provide cover for businesses. The EQC payout is limited to the first $ 100,000 plus GST of any individual claim, with any amount above that covered by
5290-540: The South Island were affected as their distribution centres in Christchurch were closed. Both The Warehouse and Progressive Enterprises (owners of Countdown ), which have their sole South Island distribution centres in Christchurch, had to ship essential products to their South Island stores from the North Island, while Foodstuffs (owners of New World and Pak'n Save ) had to ship to all their South Island stores from their Dunedin distribution centre. Many of
5405-596: The United Kingdom, and the United States. 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". One of the lead researchers said that it is likely to be globally unique. Fault (geology) In geology , a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as
5520-650: The Waitaki District Council building to stop at 4:36 am. The earthquake also caused the Dunedin Town Hall clock and the University of Otago clocktower to stop working in Dunedin, some 350 km away from the quake epicentre. The earthquake was a wake-up call to many New Zealand residents. Two Dunedin supermarkets sold out of bottled water following the earthquake as people stocked up on emergency supplies. Major stores across
5635-738: The afternoon of Monday 6 September, the entire South Island rail network had reopened with the exception of the Main North Line between Rangiora and Addington. Freight was shuttled by road between the two points, while the TranzCoastal was replaced with a coach service. Major bridges on state highways and the Lyttelton road tunnel were inspected by the NZ Transport Agency , and found to be in structurally sound condition. The only major road closure outside Christchurch
5750-524: The building over several weeks. Demolition began on 19 October 2010 and was continuing in late January. The 1911 Anglican church of St. John's in Hororata , five kilometres south of Glentunnel , was extensively damaged when part of its tower collapsed. The port town of Lyttelton 's most notable building, the 1876 Timeball station , was also affected by the earthquake, though strengthening work completed in 2005 may have saved it from further damage. In
5865-410: The central city cordon area. Police also observed a fifty-three percent jump in the rates of domestic violence following the earthquake. Many more heart attacks than usual were reported in the days following the quake. Usually the heart unit at Christchurch Hospital handles two to three heart attacks a day, but the rate had risen to eight to ten a day after the earthquake. A record number of babies for
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#17327659055735980-625: The central city, was reported to be extensively damaged and may be beyond repair, however the Repertory Theatre website notes "Beneath the rubble the lower façade is intact with not even a broken window. Further into the theatre everything was undisturbed; the auditorium, stage area, fly tower and dressing rooms intact. The historic proscenium undamaged." Several notable buildings in the Timaru area, 160 kilometres (99 mi) southwest of Christchurch, were also badly affected. A pinnacle on
6095-407: The city of Christchurch , New Zealand's second largest city at that time. Two residents were seriously injured, one by a collapsing chimney and a second by flying glass . At least two people died and over 1,700 were injured. Mass fatalities were avoided partly due to there being few houses of unreinforced construction, although this was also aided by the quake occurring during the early hours of
6210-676: The city's welfare centres. The boil water notice for Christchurch and Banks Peninsula was lifted late on 8 September 2010, after more than 500 tests conducted over three days found no contamination. Christchurch International Airport was closed following the earthquake and flights in and out of it cancelled. It reopened at 1:30 pm, following inspection of the terminals and main runway. All schools and early childhood centres in Christchurch City, Selwyn and Waimakariri Districts were ordered shut until Monday 13 September for health and safety assessments. The city's two universities,
6325-514: The crust of the Pacific plate , near the eastern foothills of the Southern Alps at the western edge of the Canterbury Plains . The earthquake epicentre was located about 80–90 km (50–56 mi) to the south and east of the current surface expression of the Australia – Pacific plate boundary through the island (the Alpine and Hope Faults ). Though removed from the plate boundary itself,
6440-414: The crust. A thrust fault has the same sense of motion as a reverse fault, but with the dip of the fault plane at less than 45°. Thrust faults typically form ramps, flats and fault-bend (hanging wall and footwall) folds. A section of a hanging wall or foot wall where a thrust fault formed along a relatively weak bedding plane is known as a flat and a section where the thrust fault cut upward through
6555-433: The direction of extension or shortening changes during the deformation but the earlier formed faults remain active. The hade angle is defined as the complement of the dip angle; it is the angle between the fault plane and a vertical plane that strikes parallel to the fault. Ring faults , also known as caldera faults , are faults that occur within collapsed volcanic calderas and the sites of bolide strikes, such as
6670-431: The distinction, as the rock between the faults is converted to fault-bound lenses of rock and then progressively crushed. Due to friction and the rigidity of the constituent rocks, the two sides of a fault cannot always glide or flow past each other easily, and so occasionally all movement stops. The regions of higher friction along a fault plane, where it becomes locked, are called asperities . Stress builds up when
6785-501: The earthquake likely reflects right-lateral motion on one of a number of regional faults related to the overall relative motion of these plates and may be related to the overall southern propagation of the Marlborough fault system in recent geologic time. The peak ground acceleration (PGA) measured was 1.26 g (12.36 m/s ), recorded near Darfield. GNS scientists considered this an "extremely rare seismic recording made near
6900-457: The earthquake relatively unscathed, though there was some damage to the town's war memorial and hospital and some homes were extensively damaged. Duvauchelle Hotel was also seriously affected. In Oamaru , 225 kilometres southwest of Christchurch, the earthquake caused part of a chimney on the St Kevin's College principal's residence to fall through the house, and caused the clock atop
7015-431: The earthquake were reported in New Zealand. This was ascribed to the fact that the quake happened in the early hours of a Saturday morning, when most people were asleep in timber-framed homes , and "...there would almost certainly have been many deaths and serious injuries had it happened during a busy time of the day...". Another important factor was building practices which took earthquakes into account, starting after
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#17327659055737130-555: The earthquake's epicentre, was the historic home of the Deans family, one of the Canterbury Region's pioneer settler families, but was so extensively damaged that it has been described as being "practically in ruins". The seven-storey Manchester Courts (or MLC Building ), located at the busy intersection of Manchester and Hereford Streets, was extensively damaged. It was the tallest commercial building in Christchurch when it
7245-406: The earthquake's epicentre. The September 2010 earthquake caused two Christchurch residents to be seriously injured, one by a falling chimney and a second by flying glass, and led to many with less serious injuries. One person died of a heart attack suffered during the quake, with the coroner's report identifying the earthquake as being a contributing factor. Another person died after falling during
7360-423: The earthquakes and given greater understanding of their number. Studies at Haast towards the centre of the fault only identified three major rupture events in the last 1000 years. Studies at the far southern end identified seven events in the last 2000 years and the most southern 20 km (12 mi) of the fault has had 27 events since 6000 BCE. This information has been updated with better dating techniques and
7475-399: The event appears to have been an extremely complex earthquake that involved up to seven faults. At 7 August 2012, the area had experienced 11,000+ recorded aftershocks of magnitude 2 or more, including 26 over 5.0 magnitude , and 2 over 6.0 magnitude. Many caused further damage to buildings in the Christchurch central business district , and some were felt as far away as 300 km to
7590-409: The fault (called a piercing point ). In practice, it is usually only possible to find the slip direction of faults, and an approximation of the heave and throw vector. The two sides of a non-vertical fault are known as the hanging wall and footwall . The hanging wall occurs above the fault plane and the footwall occurs below it. This terminology comes from mining: when working a tabular ore body,
7705-532: The fault is the vertical component of the separation and the heave of the fault is the horizontal component, as in "Throw up and heave out". The vector of slip can be qualitatively assessed by studying any drag folding of strata, which may be visible on either side of the fault. Drag folding is a zone of folding close to a fault that likely arises from frictional resistance to movement on the fault. The direction and magnitude of heave and throw can be measured only by finding common intersection points on either side of
7820-465: The fault movement. Faults are mainly classified in terms of the angle that the fault plane makes with the Earth's surface, known as the dip , and the direction of slip along the fault plane. Based on the direction of slip, faults can be categorized as: In a strike-slip fault (also known as a wrench fault , tear fault or transcurrent fault ), the fault surface (plane) is usually near vertical, and
7935-406: The fault. A fault in ductile rocks can also release instantaneously when the strain rate is too great. Slip is defined as the relative movement of geological features present on either side of a fault plane. A fault's sense of slip is defined as the relative motion of the rock on each side of the fault concerning the other side. In measuring the horizontal or vertical separation, the throw of
8050-399: The fault. The water then can arise in hot springs with temperatures of over 50 °C (122 °F) in the fault valley, although the temperature of the water at depth is much more extreme. Most of the movement along the fault occurs in this zone. In outcrop, the fault zone is overlain by mylonites which formed at depth and have been uplifted by the fault. A structural study of a segment of
8165-428: The footwall moves laterally either left or right with very little vertical motion. Strike-slip faults with left-lateral motion are also known as sinistral faults and those with right-lateral motion as dextral faults. Each is defined by the direction of movement of the ground as would be seen by an observer on the opposite side of the fault. A special class of strike-slip fault is the transform fault when it forms
8280-531: The footwall. The dip of most normal faults is at least 60 degrees but some normal faults dip at less than 45 degrees. A downthrown block between two normal faults dipping towards each other is a graben . A block stranded between two grabens, and therefore two normal faults dipping away from each other, is a horst . A sequence of grabens and horsts on the surface of the Earth produces a characteristic basin and range topography . Normal faults can evolve into listric faults, with their plane dip being steeper near
8395-711: The former Canterbury College buildings, was less fortunate, with moderate damage to the Great Hall, the Clocktower, and the Observatory. The structure of the University of Canterbury 's buildings survived the earthquake, but its museum collection of Greek and Roman artefacts (the Logie Memorial Collection) was significantly damaged. Also, as many of the bookshelves in the main library were toppled, with repairs expected to take until Christmas,
8510-429: The geometric gap, and depending on its rheology , the hanging wall might fold and slide downwards into the gap and produce rollover folding , or break into further faults and blocks which fil in the gap. If faults form, imbrication fans or domino faulting may form. A reverse fault is the opposite of a normal fault—the hanging wall moves up relative to the footwall. Reverse faults indicate compressive shortening of
8625-491: The implied mechanism of deformation. A fault that passes through different levels of the lithosphere will have many different types of fault rock developed along its surface. Continued dip-slip displacement tends to juxtapose fault rocks characteristic of different crustal levels, with varying degrees of overprinting. This effect is particularly clear in the case of detachment faults and major thrust faults . The main types of fault rock include: In geotechnical engineering ,
8740-406: The insurance company holding the policy. The insurance companies themselves had limited or no exposure, having offloaded most of their risk to reinsurance companies. The EQC had reinsurance of $ 2.5 billion with a $ 1.5 billion excess, so its exposure was the first $ 1.5 billion and any amount after the first $ 4 billion. It had a total fund prior to this earthquake of approx $ 6 billion. For comparison,
8855-551: The interior in good order. The City Council's own new Civic Building sustained some interior damage, mainly to fixtures and fittings that delayed it being reopened for a week. Others, such as the city's International Antarctic Centre and Christchurch Art Gallery , the latter of which served as the Civil Defence Headquarters during the earthquake aftermath, suffered little or no damage and were able to be used immediately. Christchurch Arts Centre , housed in
8970-737: The island. At this point, it splits into a set of smaller faults known as the Marlborough fault system . 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. The Hope Fault is thought to represent the primary continuation of the Alpine Fault. The Australian plate, which
9085-464: The largest faults on Earth and give rise to the largest earthquakes. A fault which has a component of dip-slip and a component of strike-slip is termed an oblique-slip fault . Nearly all faults have some component of both dip-slip and strike-slip; hence, defining a fault as oblique requires both dip and strike components to be measurable and significant. Some oblique faults occur within transtensional and transpressional regimes, and others occur where
9200-518: The later Christchurch earthquake in February 2011 the building was severely damaged, and it is planned by Heritage New Zealand for it to be dismantled, with the possibility of reconstruction. The Valley Inn Tavern in Heathcote , built in 1877, survived the initial quake, but had to be torn down after the large 5.1 magnitude aftershock. Lincoln 's historic 1883 public house, The Famous Grouse,
9315-408: The miner stood with the footwall under his feet and with the hanging wall above him. These terms are important for distinguishing different dip-slip fault types: reverse faults and normal faults. In a reverse fault, the hanging wall displaces upward, while in a normal fault the hanging wall displaces downward. Distinguishing between these two fault types is important for determining the stress regime of
9430-419: The morning when most people were off the street. The earthquake's epicentre was 40 kilometres (25 mi) west of Christchurch, close to the town of Darfield . The hypocentre was at a depth of 10 km. A foreshock of roughly magnitude 5.8 hit five seconds before the main quake, and strong aftershocks were reported, up to magnitude 5.4. The quake was felt as lasting up to 40 seconds, and
9545-513: The most badly affected structures in both Christchurch and the surrounding districts were old buildings, including several notable landmarks. Heritage New Zealand board member Anna Crighton said the earthquake had been "unbelievably destructive." The historic homesteads of Hororata and Homebush inland from Christchurch were both extensively damaged, as were Ohinetahi homestead and Godley House on Banks Peninsula . Homebush, located four kilometres from Glentunnel and only 15 kilometres from
9660-435: The most common. With the passage of time, a regional reversal between tensional and compressional stresses (or vice-versa) might occur, and faults may be reactivated with their relative block movement inverted in opposite directions to the original movement (fault inversion). In such a way, a normal fault may therefore become a reverse fault and vice versa. In a normal fault, the hanging wall moves downward, relative to
9775-538: The mountains leading to more erosion. This, along with isostatic constraints, has kept the Southern Alps less than 4,000 m (13,000 ft) high. Uplift on the Alpine Fault has led to the exposure of deep metamorphic rocks near the fault within the Southern Alps. This includes mylonites and the Alpine Schist , which increases in metamorphic grade towards the fault. The eroded material has formed
9890-422: The movement on the proto-Alpine Fault was exclusively strike-slip. The Southern Alps had not yet formed and most of New Zealand was covered in water. Then uplift slowly began as the plate motion became slightly oblique to the strike of the Alpine Fault. In the last 12 million years, the Southern Alps have been uplifted approximately 20 km (12 mi), however, as this has occurred more rain has been trapped by
10005-494: The opposite direction. These faults may be accompanied by rollover anticlines (e.g. the Niger Delta Structural Style). All faults have a measurable thickness, made up of deformed rock characteristic of the level in the crust where the faulting happened, of the rock types affected by the fault and of the presence and nature of any mineralising fluids . Fault rocks are classified by their textures and
10120-659: The plates, meaning that the fault has a significant high-angle reverse oblique component to its displacement. In the northern section of the fault the transition to the Marlborough Fault System reflects transfer displacement between the mainly transform plate boundary of the Alpine fault and the mainly destructive boundary further northwards from the Hikurangi Subduction Zone to the Kermadec Trench . This has resulted in
10235-415: The probability of an earthquake occurring before 2068 was 75 percent. Large ruptures can also trigger earthquakes on the faults continuing north from the Alpine Fault. 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. A 2018 study says that a significant rupture in
10350-529: The public understood it as well, or that it widely influenced development, buying or building decisions. Liquefaction risk at the Pegasus Town site was identified in 2005, so the developers spent approximately $ 20 million on soil compaction, and the ground there held firm during the quake. The media have remarked on the lack of casualties, despite the close parallels of the quake to incidents that have had devastating consequences in other countries, such as
10465-505: The quake. In 2020 it was suggested in the journal Earthquake Spectra that someone died after being thrown off the toilet, although Coronial Services is unable to find the coroner's report for that death. The subsequent 22 February 2011 aftershock caused a large number of deaths and casualties, along with significant damage to buildings and infrastructure. Total Earthquake Commission (EQC), private insurance and individual costs were estimated to reach as high as NZ$ 4 billion according to
10580-478: The region, some as close as 20 km to central Christchurch. The closest faults to Christchurch capable of producing powerful earthquakes occur in the Rangiora - Cust area, near Hororata , and near Darfield . However, the 2010 quake ruptured the ground surface on a previously unknown fault and involved slip on up to seven individual faults. The main quake occurred as a result of strike-slip faulting within
10695-412: The right time for—and type of— igneous differentiation . At a given time differentiated magmas would burst violently out of the fault-traps and head to shallower places in the crust where porphyry copper deposits would be formed. As faults are zones of weakness, they facilitate the interaction of water with the surrounding rock and enhance chemical weathering . The enhanced chemical weathering increases
10810-561: The size of the weathered zone and hence creates more space for groundwater . Fault zones act as aquifers and also assist groundwater transport. 2010 Canterbury earthquake The 2010 Canterbury earthquake (also known as the Darfield earthquake ) struck the South Island of New Zealand with a moment magnitude of 7.1 at 4:35 am local time on 4 September , and had a maximum perceived intensity of X ( Extreme ) on
10925-551: The south in Dunedin . Notable aftershocks, in chronological order, include: The Earthquake Commission has published two Geotechnical Land Damage Assessment & Reinstatement Report[s] . The first Stage-1 report was published on 21 October 2010. The report briefly describes the mechanics of the earthquake, underlying geology, residential land damage assessment, reconstruction considerations, land and building reinstatement, and remediation options. The second Stage-2 report
11040-402: The southern edge due to transpression . The study discussed the short-lived nature of the releasing bend (on the order of 10 to 10 years), during which there were 450 – 1650 m of dextral displacement. The nature of the displacement served as an example of the kinds of ephemeral structures that can develop along a mature strike-slip fault system. There have been no major historical earthquakes on
11155-444: The southwest of Christchurch, was contaminated. Power to up to 75 percent of the city was disrupted. Christchurch Hospital was forced to use emergency generators in the immediate aftermath of the quake. About 90% of the electricity in Christchurch had been restored by 6:00 pm the day of the earthquake. The repair of electricity was estimated to be more difficult in the rural areas. One building caught fire after its electricity
11270-416: The stratigraphic sequence is known as a ramp . Typically, thrust faults move within formations by forming flats and climbing up sections with ramps. This results in the hanging wall flat (or a portion thereof) lying atop the foot wall ramp as shown in the fault-bend fold diagram. Thrust faults form nappes and klippen in the large thrust belts. Subduction zones are a special class of thrusts that form
11385-400: The surface, then shallower with increased depth, with the fault plane curving into the Earth. They can also form where the hanging wall is absent (such as on a cliff), where the footwall may slump in a manner that creates multiple listric faults. The fault panes of listric faults can further flatten and evolve into a horizontal or near-horizontal plane, where slip progresses horizontally along
11500-576: The tower of St Mary's Anglican Church tower fell to the ground, and the recently restored tower itself sustained "significant cracking". The spire of St. Joseph's Catholic Church in Temuka was also shifted 10 centimetres (4 in) by the earthquake, leaving it precariously balanced, and the town's historic Royal Hotel was also damaged. Heritage experts urged building owners not to hastily demolish their buildings. The mayor warned of significant penalties for demolishing buildings without consent, and launched
11615-410: The town "will never be the same again". As noted above, damage to buried pipes may have allowed sewage to contaminate the residential water supply, and residents were warned to boil tap water before using it for brushing teeth, drinking, and washing or cooking food. A boil water notice for most of Selwyn District was lifted on 9 September. E. coli had been found in a water sample from Kaiapoi, and
11730-467: The two sides of the previously unknown fault. In many towns outside Christchurch, the electrical grid was disrupted, with it taking an estimated two days to fully restore power to those affected. Power outages were reported as far away as Dunedin. Access was restricted to over 350 homes in the town of Kaiapoi, of which about 100 were deemed unsafe. Some 22 commercial properties were deemed unsafe. According to Ron Keating, Mayor of Waimakariri District,
11845-656: The university arranged electronic access to many academic publishers databases for students about to sit exams. The Oxford Terrace Baptist Church , constructed 1881–1882, was extensively damaged. Several other Christchurch area churches also suffered serious damage, including St. Mary's Anglican church in Merivale , St. John's Anglican church in Latimer Square, and the Rugby Street Methodist church. The city's Repertory Theatre, on Kilmore Street in
11960-401: The up to 800 kilometres (500 mi) long fault was remarkably consistent, rupturing on average every 330 years, at intervals ranging from 140 years to 510 years. 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
12075-582: The vicinity. In California, for example, new building construction has been prohibited directly on or near faults that have moved within the Holocene Epoch (the last 11,700 years) of the Earth's geological history. Also, faults that have shown movement during the Holocene plus Pleistocene Epochs (the last 2.6 million years) may receive consideration, especially for critical structures such as power plants, dams, hospitals, and schools. Geologists assess
12190-483: Was a slip in the Rakaia Gorge , blocking State Highway 77 . The slip was partially cleared by 4 pm to allow a single lane of traffic through the site. Kaiapoi's main road was closed for a few days. The quake caused damage to historic buildings in Lyttelton , Christchurch's port town, including cracks in a church and the destruction of parts of a hotel. The Akaroa area of Banks Peninsula came through
12305-826: Was also irreparably damaged and was demolished within days of the earthquake. Many of Christchurch's major landmarks survived intact, including the Canterbury Provincial Council Buildings , the Anglican cathedral , and Christ's College . The Catholic Cathedral of the Blessed Sacrament (Christchurch Basilica) also survived, although it suffered severe structural damage and also had some windows broken. The central city's iconic Christchurch Press building also survived with only minor damage. Most modern buildings performed as they were designed to do, preserving life rather than keeping
12420-572: Was built in 1905–06 for the New Zealand Express Company, and blended 1890s Chicago Skyscraper style with English Edwardian architecture. The building had a Category One Historic Places trust classification , but was deemed unsafe and was one of just two historic CBD buildings the City Council initially proposed for immediate demolition. That decision was reversed hours later when the building's owner proposed to dismantle
12535-544: Was estimated at 75 percent in 2021. 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 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
12650-752: Was felt widely across the South Island, and in the North Island as far north as New Plymouth . As the epicentre was on land away from the coast, no tsunami occurred. The National Crisis Management Centre in the basement of the Beehive in Wellington was activated, and Civil Defence declared a state of emergency for Christchurch, the Selwyn District , and the Waimakariri District , while Selwyn District, Waimakariri and Timaru activated their emergency operation centres. Initially,
12765-477: Was in relatively rapid constant movement and helped to overthrow the old geosynclinal hypothesis in favour of plate tectonics. In 1964 a 25-metre-long concrete wall was built across the fault to measure the fault's movements and to find if it moves slowly over time or suddenly during big earthquakes. The wall has not moved since being built, which indicates that the build up of energy is released suddenly during large earthquakes. Richard Norris and Alan Cooper from
12880-598: Was inferred to be from frictional heating along the fault not uplift of deeper geological sequences. Richard H. Sibson from the same university also used the Alpine Fault to refine his nomenclature of fault rocks which gained international adherence. Chorus 's dark fibre cables that pass through the Alpine Fault, from the north and south of Haast, are used for distributed acoustic sensing , which detects cable movement produced by earthquakes. Measurements are made using 7,250 'interrogator' locations, spaced four metres apart, which emit and detect pulses of light, generating about
12995-430: Was published on 1 December 2010. It divides the quake-affected areas into three zones, and outlines the remediation plans for these areas. Most of the damage was in the area surrounding the epicentre, including the city of Christchurch , New Zealand's second-largest urban area with a population of 386,000. Minor damage was reported as far away as Dunedin and Nelson , both around 300–350 kilometres (190–220 mi) from
13110-506: Was turned back on, igniting leaking LPG in the building. The fire was quickly extinguished by the Fire Service before it could spread. Damage to buried pipes may have allowed sewage to contaminate the residential water supply. Residents were warned to boil tap water before using it for brushing teeth, drinking, and washing or cooking food. Several cases of gastroenteritis were reported. By 7 September 28 cases had been observed at
13225-559: Was up to $ 40 billion, making it the fifth-biggest insurance event in the world since 1953. In the first eighty years of European settlement in Christchurch (1850–1930), four earthquakes caused significant damage, the last of these centred at Motunau on the North Canterbury coast in 1922. Modelling conducted for the New Zealand Earthquake Commission (EQC) in 1991 found that earthquakes with
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