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34-705: The 1989 Newcastle earthquake was an intraplate earthquake that occurred in Newcastle, New South Wales on Thursday 28 December. The shock measured 5.6 on the Richter scale and was one of Australia's most serious natural disasters , killing 13 people and injuring more than 160. The damage bill has been estimated at A$ 4 billion (or $ 9.5 billion in 2022, adjusted for inflation), including an insured loss of about $ 1 billion (or $ 2.4 billion in 2022, adjusted for inflation). The effects were felt over an area of around 200,000 square kilometres (77,000 sq mi) in

68-468: A graben , or more commonly a half-graben with normal faulting and rift-flank uplifts mainly on one side. Where rifts remain above sea level they form a rift valley , which may be filled by water forming a rift lake . The axis of the rift area may contain volcanic rocks , and active volcanism is a part of many, but not all, active rift systems. Major rifts occur along the central axis of most mid-ocean ridges , where new oceanic crust and lithosphere

102-449: A lacustrine environment or in a restricted marine environment, although not all rifts contain such sequences. Reservoir rocks may be developed in pre-rift, syn-rift and post-rift sequences. Effective regional seals may be present within the post-rift sequence if mudstones or evaporites are deposited. Just over half of estimated oil reserves are found associated with rifts containing marine syn-rift and post-rift sequences, just under

136-417: A causative fault can be located with great accuracy, and in most cases these line up in patterns consistent with faulting. Cryoseisms can sometimes be mistaken for intraplate earthquakes. Rift In geology , a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics . Typical rift features are a central linear downfaulted depression, called

170-403: A kind of orogeneses in extensional settings, which is referred as to rifting orogeny. Once rifting ceases, the mantle beneath the rift cools and this is accompanied by a broad area of post-rift subsidence. The amount of subsidence is directly related to the amount of thinning during the rifting phase calculated as the beta factor (initial crustal thickness divided by final crustal thickness), but

204-538: A large intraplate earthquake devastated the region of Gujarat , India. The earthquake occurred far from any plate boundaries, which meant the region above the epicenter was unprepared for earthquakes. In particular, the Kutch district suffered tremendous damage, where the death toll was over 12,000 and the total death toll was higher than 20,000. In 2017, the 24–29 km deep magnitude 6.5 Botswana earthquake that shook eastern Botswana occurred at over 300 km from

238-438: A mid-oceanic ridge and a set of conjugate margins separated by an oceanic basin. Rifting may be active, and controlled by mantle convection . It may also be passive, and driven by far-field tectonic forces that stretch the lithosphere. Margin architecture develops due to spatial and temporal relationships between extensional deformation phases. Margin segmentation eventually leads to the formation of rift domains with variations of

272-557: A series of separate segments that together form the linear zone characteristic of rifts. The individual rift segments have a dominantly half-graben geometry, controlled by a single basin-bounding fault. Segment lengths vary between rifts, depending on the elastic thickness of the lithosphere. Areas of thick colder lithosphere, such as the Baikal Rift have segment lengths in excess of 80 km, while in areas of warmer thin lithosphere, segment lengths may be less than 30 km. Along

306-717: A simple relay ramp at the overlap between two major faults of the same polarity, to zones of high structural complexity, particularly where the segments have opposite polarity. Accommodation zones may be located where older crustal structures intersect the rift axis. In the Gulf of Suez rift, the Zaafarana accommodation zone is located where a shear zone in the Arabian-Nubian Shield meets the rift. Rift flanks or shoulders are elevated areas around rifts. Rift shoulders are typically about 70 km wide. Contrary to what

340-417: A tsunami generated by the quake. Many cities live with the seismic risk of a rare, large intraplate earthquake. The cause of these earthquakes is often uncertain. In many cases, the causative fault is deeply buried and sometimes cannot even be found. Some studies have shown that quakes can be caused by fluids moving up the crust along ancient fault zones. In such circumstances, it is difficult to estimate

374-402: Is also affected by the degree to which the rift basin is filled at each stage, due to the greater density of sediments in contrast to water. The simple 'McKenzie model' of rifting, which considers the rifting stage to be instantaneous, provides a good first order estimate of the amount of crustal thinning from observations of the amount of post-rift subsidence. This has generally been replaced by

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408-451: Is created along a divergent boundary between two tectonic plates . Failed rifts are the result of continental rifting that failed to continue to the point of break-up. Typically the transition from rifting to spreading develops at a triple junction where three converging rifts meet over a hotspot . Two of these evolve to the point of seafloor spreading, while the third ultimately fails, becoming an aulacogen . Most rifts consist of

442-433: The 2011 Christchurch earthquake , the 2012 Indian Ocean earthquakes , the 2017 Puebla earthquake , the 1811–1812 New Madrid earthquakes , and the 1886 Charleston earthquake . The Earth's crust is made up of seven primary and eight secondary tectonic plates , plus dozens of tertiary microplates. The large plates move very slowly on top of convection currents in the underlying mantle . Because they do not all move in

476-654: The Boston (Cape Ann) earthquake of 1755 (estimated magnitude 6.0 to 6.3), earthquakes felt in New York City in 1737 and 1884 (both quakes estimated at 5.5 magnitude), and the Charleston earthquake in South Carolina in 1886 (estimated magnitude 6.5 to 7.3). The Charleston quake was particularly surprising because, unlike Boston and New York, the area had almost no history of even minor earthquakes. In 2001,

510-473: The Moho topography, including proximal domain with fault-rotated crustal blocks, necking zone with thinning of crustal basement , distal domain with deep sag basins, ocean-continent transition and oceanic domain. Deformation and magmatism interact during rift evolution. Magma-rich and magma-poor rifted margins may be formed. Magma-rich margins include major volcanic features. Globally, volcanic margins represent

544-603: The seismic hazard for a given city, especially if there was only one earthquake in historical times. Some progress is being made in understanding the fault mechanics driving these earthquakes. Intraplate earthquakes may be unrelated to ancient fault zones and instead caused by deglaciation or erosion. Scientists continue to search for the causes of these earthquakes, and especially for some indication of how often they recur. The best success has come with detailed micro-seismic monitoring, involving dense arrays of seismometers . In this manner, very small earthquakes associated with

578-659: The 'flexural cantilever model', which takes into account the geometry of the rift faults and the flexural isostasy of the upper part of the crust. Some rifts show a complex and prolonged history of rifting, with several distinct phases. The North Sea rift shows evidence of several separate rift phases from the Permian through to the Earliest Cretaceous , a period of over 100 million years. Rifting may lead to continental breakup and formation of oceanic basins. Successful rifting leads to seafloor spreading along

612-452: The axis of the rift the position, and in some cases the polarity (the dip direction), of the main rift bounding fault changes from segment to segment. Segment boundaries often have a more complex structure and generally cross the rift axis at a high angle. These segment boundary zones accommodate the differences in fault displacement between the segments and are therefore known as accommodation zones. Accommodation zones take various forms, from

646-474: The city on the day of the earthquake was lower than usual, due to a strike by local bus drivers. The earthquake struck in the middle of an interview by a local television station NBN with a union representative. The names of all 13 victims were published later in newspapers such as the Maitland Mercury In early 2007, a United States academic claimed that coal mining in the region triggered

680-655: The crust vulnerable to regional tectonic strain. Intraslab earthquakes radiate more seismic energy than interplate earthquakes ( megathrust earthquakes ) of a similar magnitude. This variation makes seismic energy a better measure for the potential macroseismic effects of an earthquake than the more common seismic moment used to calculate the magnitude M w  . Examples of intraplate earthquakes include those in Mineral, Virginia , in 2011 (estimated magnitude 5.8), Newcastle, New South Wales in 1989 , New Madrid in 1811 and 1812 (estimated magnitude as high as 8.6),

714-493: The death of a woman in Broadmeadow from earthquake-related shock, the final death toll was raised to 13. The earthquake caused damage to over 35,000 homes, 147 schools, and 3,000 commercial and/or other buildings, with significant damage (i.e. damage worth over $ 1,000; $ 2,400 in 2022 adjusted for inflation) caused to 10,000 homes and 42 schools (structural damage), within the immediate Newcastle area. The number of people in

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748-469: The development of isolated basins. In subaerial rifts, for example, drainage at the onset of rifting is generally internal, with no element of through drainage. As the rift evolves, some of the individual fault segments grow, eventually becoming linked together to form the larger bounding faults. Subsequent extension becomes concentrated on these faults. The longer faults and wider fault spacing leads to more continuous areas of fault-related subsidence along

782-473: The earthquake, although earthquake activity has been present in the area at least since European settlement first occurred. That is in addition to the statement by the former head of the earthquake monitoring group at Geoscience Australia , Dr David Denham, that the Newcastle earthquake occurred some distance from mining activity: "The depths of the focus of the earthquake was about 13, 14 kilometres, whereas

816-567: The majority of passive continental margins. Magma-starved rifted margins are affected by large-scale faulting and crustal hyperextension. As a consequence, upper mantle peridotites and gabbros are commonly exposed and serpentinized along extensional detachments at the seafloor. Many rifts are the sites of at least minor magmatic activity , particularly in the early stages of rifting. Alkali basalts and bimodal volcanism are common products of rift-related magmatism. Recent studies indicate that post-collisional granites in collisional orogens are

850-435: The minimum strength. Songs about the Newcastle earthquake include Intraplate earthquake Intraplate earthquakes are relatively rare compared to the more familiar interplate earthquakes. Buildings far from plate boundaries are rarely protected with seismic retrofitting , so large intraplate earthquakes can inflict heavy damage. Examples of damaging intraplate earthquakes are the devastating 2001 Gujarat earthquake ,

884-778: The nearest active plate boundary. The event occurred in an underpopulated area of Botswana. The 1888 earthquake in Río de la Plata was an intraplate quake, from reactivated faults in the Quilmes Trough, far from the boundaries of the South American plate . With a magnitude greater than 5.0 it was felt "in the cities of Buenos Aires, La Plata and other small towns and villages along the Rio de Plata coastal regions." The towns of Punta del Este and Maldonado in Uruguay were hit by

918-439: The ones associated with mining, they're actually right close to the mine, because that's where the stress release takes place." Despite records of previous earthquakes in the area, even the most recent construction codes in Newcastle at the time of the earthquake (issued in 1979) required neither the adoption of earthquake-resistant design nor the strengthening of old buildings, although they did encourage owners to provide more than

952-404: The product of rifting magmatism at converged plate margins. The sedimentary rocks associated with continental rifts host important deposits of both minerals and hydrocarbons . SedEx mineral deposits are found mainly in continental rift settings. They form within post-rift sequences when hydrothermal fluids associated with magmatic activity are expelled at the seabed. Continental rifts are

986-484: The rift axis. Significant uplift of the rift shoulders develops at this stage, strongly influencing drainage and sedimentation in the rift basins. During the climax of lithospheric rifting, as the crust is thinned, the Earth's surface subsides and the Moho becomes correspondingly raised. At the same time, the mantle lithosphere becomes thinned, causing a rise of the top of the asthenosphere. This brings high heat flow from

1020-408: The same direction, plates often directly collide or slide laterally along each other , a tectonic environment that makes interplate earthquakes frequent. By contrast, relatively few earthquakes occur in intraplate environments away from plate junctures. These earthquakes often occur at the location of ancient failed rifts , partial fractures of existing plates, because they may leave a weakness in

1054-521: The sites of significant oil and gas accumulations, such as the Viking Graben and the Gulf of Suez Rift . Thirty percent of giant oil and gas fields are found within such a setting. In 1999 it was estimated that there were 200 billion barrels of recoverable oil reserves hosted in rifts. Source rocks are often developed within the sediments filling the active rift ( syn-rift ), forming either in

1989 Newcastle earthquake - Misplaced Pages Continue

1088-657: The state of New South Wales , with isolated reports of movement in areas up to 800 kilometres (500 mi) from Newcastle. Damage to buildings and facilities was reported over an area of 9,000 km (3,500 sq mi). The highest death toll and damage occurred at the Newcastle Workers Club, where the floor collapsed. Nine people were killed and many more were trapped beneath the rubble. Another three people were crushed to death when masonry from building façades collapsed onto awnings on Beaumont Street , Hamilton , an inner-city suburb of Newcastle. Following

1122-491: The upwelling asthenosphere into the thinning lithosphere, heating the orogenic lithosphere for dehydration melting, typically causing extreme metamorphism at high thermal gradients of greater than 30 °C. The metamorphic products are high to ultrahigh temperature granulites and their associated migmatite and granites in collisional orogens, with possible emplacement of metamorphic core complexes in continental rift zones but oceanic core complexes in spreading ridges. This leads to

1156-549: Was previously thought, elevated passive continental margins (EPCM) such as the Brazilian Highlands , the Scandinavian Mountains and India's Western Ghats , are not rift shoulders. The formation of rift basins and strain localization reflects rift maturity. At the onset of rifting, the upper part of the lithosphere starts to extend on a series of initially unconnected normal faults , leading to

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