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66-681: During the late Neogene period (23.03-2.58 million years ago), the Japan Trench underwent a period of plate convergence between the Pacific and Okhotsk plates. Based on the sediment sequence during this time, there appears to have been little net accretion of sediment onto the overlying plate as well as evidence of mild erosion at the base of the convergent margin. During the Cretaceous (145.5-66 million years ago) to early Paleogene (66–23.03 ma), evidence of andesitic volcanism along with

132-405: 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

198-860: 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

264-582: 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

330-500: 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

396-410: 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

462-408: 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

528-409: 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 the distinction, as

594-559: A series of continental glaciations in the Quaternary Period that followed. In ICS terminology, from upper (later, more recent) to lower (earlier): The Pliocene Epoch is subdivided into two ages: The Miocene Epoch is subdivided into six ages: In different geophysical regions of the world, other regional names are also used for the same or overlapping ages and other timeline subdivisions. The terms Neogene System (formal) and Upper Tertiary System (informal) describe

660-481: Is due to the comparatively fine divisibility of time units as time approaches the present, and due to geological preservation that causes the youngest sedimentary geological record to be preserved over a much larger area and to reflect many more environments than the older geological record. By dividing the Cenozoic Era into three (arguably two) periods ( Paleogene , Neogene, Quaternary ) instead of seven epochs,

726-543: 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

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792-702: Is often seen as an analogous climate to the projected climate of the near future as a result of anthropogenic global warming . Towards the end of the Pliocene, decreased heat transport towards the Antarctic resulting from a weakening of the Indonesian Throughflow (ITF) cooled the Earth, a process that exacerbated itself in a positive feedback as sea levels dropped and the ITF diminished and further limited

858-463: 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

924-793: The Paleogene . The Early Miocene was relatively cool; Early Miocene mid-latitude seawater and continental thermal gradients were already very similar to those of the present. During the Middle Miocene , Earth entered a warm phase known as the Middle Miocene Climatic Optimum (MMCO), which was driven by the emplacement of the Columbia River Basalt Group . Around 11 Ma, the Middle Miocene Warm Interval gave way to

990-603: The Austrian palaeontologist Moritz Hörnes (1815–1868). The earlier term Tertiary Period was used to define the span of time now covered by Paleogene and Neogene and, despite no longer being recognized as a formal stratigraphic term , "Tertiary" still sometimes remains in informal use. During this period, mammals and birds continued to evolve into modern forms, while other groups of life remained relatively unchanged. The first humans ( Homo habilis ) appeared in Africa near

1056-492: The Fukushima-oki region in 1938, registering five in total. The magnitudes were 7.4, 7.7, 7.8, 7.7 and 7.1. During December 1994, transient crustal movements were recorded by a Global Positioning System (GPS) network after an inter-plate earthquake arose within the Japan Trench. This very subtle, but distinct disruption observed indicates a "silent" slow fault slip was triggered by this. A recorded magnitude 7.7 earthquake

1122-607: The Gelasian Age, which was formerly considered part of the Neogene Period and Pliocene Epoch. Thus the Neogene Period ends bounding the succeeding Quaternary Period at 2.58 Mya. Normal fault In geology , a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth 's crust result from

1188-574: The Japan Trench occurs along the associated subduction zone at disruptive convergent plate boundaries between the Okhotsk and subducting Pacific plate. The continuing movement along these plate boundaries occur at a depth of about 8,000 metres (26,247 ft). During the year of 1896, a magnitude (M) 6.8 earthquake was recorded within the Japan Trench. Later during the same year, a destructive magnitude 8.5 earthquake occurred resulting in two tsunamis wreaking havoc. A series of M7 earthquakes occurred at

1254-505: The Miocene-Pliocene boundary. The first hominins , the ancestors of humans, may have appeared in southern Europe and migrated into Africa. The first humans (belonging to the species Homo habilis ) appeared in Africa near the end of the period. About 20 million years ago gymnosperms in the form of some conifer and cycad groups started to diversify and produce more species due to the changing conditions. In response to

1320-777: The Neogene and the Pliocene end at 2.58 Ma, that the Gelasian be transferred to the Pleistocene, and the Quaternary be recognized as the third period in the Cenozoic, citing key changes in Earth's climate, oceans, and biota that occurred 2.58 Ma and its correspondence to the Gauss-Matuyama magnetostratigraphic boundary . In 2006 ICS and INQUA reached a compromise that made Quaternary a sub-era, subdividing Cenozoic into

1386-562: The Pliocene Warm Interval (PWI), interrupting the longer-term cooling trend. The Pliocene Thermal Maximum (PTM) occurred between 3.3 and 3.0 Ma. During the Pliocene, Green Sahara phases of wet conditions in North Africa were frequent and occurred about every 21 kyr, being especially intense when Earth's orbit's eccentricity was high. The PWI had similar levels of atmospheric carbon dioxide to contemporary times and

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1452-607: The Tohoku earthquake and its potential as one of the main triggers of tsunami wave formation occurring along the northeast coast of Japan. In 2013, the Integrated Ocean Drilling Program (IODP) Expedition 343 collected sediment samples from drilling at the plate boundary fault zone along the Japan Trench. The sediment cores collected exhibited low friction at coseismic slip velocities as well as at low slip velocities. These studies and samples have supported

1518-403: 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 is the plane that represents the fracture surface of

1584-544: The atmosphere, C 4 plants expanded and reached ecological dominance in grasslands during the last 10 million years. Also Asteraceae (daisies) went through a significant adaptive radiation . Eucalyptus fossil leaves occur in the Miocene of New Zealand, where the genus is not native today, but have been introduced from Australia. The Neogene traditionally ended at the end of the Pliocene Epoch, just before

1650-590: The beginning of the present Quaternary Period 2.58 million years ago. It is the second period of the Cenozoic and the eleventh period of the Phanerozoic . The Neogene is sub-divided into two epochs , the earlier Miocene and the later Pliocene . Some geologists assert that the Neogene cannot be clearly delineated from the modern geological period, the Quaternary . The term "Neogene" was coined in 1853 by

1716-512: The coastline of northern Japan. The damage left about 16,000 people killed along with a catastrophic level 7 nuclear meltdown of three nuclear reactors located at the Fukushima Daiichi Nuclear Power Plant complex. The World's Bank recorded the total cost of damage to be about US$ 235 billion, making it the costliest natural disaster in history . Large magnitude and frequent earthquake activity occurring at

1782-464: The cooler, seasonal climate, tropical plant species gave way to deciduous ones and grasslands replaced many forests. Grasses therefore greatly diversified, and herbivorous mammals evolved alongside it, creating the many grazing animals of today such as horses , antelope , and bison . Ice age mammals like the mammoths and woolly rhinoceros were common in Pliocene . With lower levels of CO 2 in

1848-414: 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

1914-662: The development of a large syncline and a thickened sediment sequence indicate the possible development of a forearc basin . Activity during the Cretaceous included subduction events as well as extensive accretion of sediment to the Northeastern Japan Arc that continues today. Volcanism decreased during the early Paleogene (66 ma), exposing the thickened Cretaceous-Paleogene 160 kilometres (99 mi) thick sediment sequence. Once this sediment sequence subsided, volcanism once again resumed. Seismic activity along

1980-433: 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

2046-654: The end of the period. Some continental movements took place, the most significant event being the connection of North and South America at the Isthmus of Panama , late in the Pliocene. This cut off the warm ocean currents from the Pacific to the Atlantic Ocean, leaving only the Gulf Stream to transfer heat to the Arctic Ocean . The global climate cooled considerably throughout the Neogene, culminating in

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2112-409: 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,

2178-532: 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

2244-413: 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

2310-406: 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

2376-428: 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

2442-531: 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

2508-429: 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

2574-467: The heat transported southward by the Leeuwin Current . By the end of the period the first of a series of glaciations of the current Ice Age began. Marine and continental flora and fauna have a modern appearance. The reptile group Choristodera went extinct in the early part of the period, while the amphibians known as Allocaudata disappeared at the end of it. Neogene also marked the end of

2640-469: The idea that these frictional properties of the fault zone possibly triggered the shallow and large slip during the Tohoku earthquake. Sediment samples within the Japan Trench consist mainly of highly localized clay-rich material. The subducting Pacific plate creates basins along the ocean floor of the Japan Trench, accommodating the deposition of fine-grained turbidites and interseismic sediment deposits through turbidity currents . These turbidites preserve

2706-491: 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 ,

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2772-464: 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

2838-408: 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

2904-435: 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

2970-486: The much cooler Late Miocene. The ice caps on both poles began to grow and thicken, a process enhanced by positive feedbacks from increased formation of sea ice. Between 7 and 5.3 Ma, a decrease in global temperatures termed the Late Miocene Cooling (LMC) ensued, driven by decreases in carbon dioxide concentrations. During the Pliocene, from about 5.3 to 2.7 Ma, another warm interval occurred, being known as

3036-473: The northern Japan Trench may be explained by variations in surface roughness of the subducting Pacific plate. Regions of smooth ocean floor subduction are correlated with typically large under-thrust earthquakes within the deeper part of the plate interface zone. No earthquakes have been observed or reported from the shallow aseismic zone of the north Japan Trench. Regions of rough ocean bottom subduction are correlated with large normal faulting earthquakes within

3102-611: The old classical Tertiary and Quaternary, a compromise that was rejected by International Union of Geological Sciences because it split both Neogene and Pliocene in two. Following formal discussions at the 2008 International Geological Congress in Oslo, Norway, the ICS decided in May 2009 to make the Quaternary the youngest period of the Cenozoic Era with its base at 2.58 Mya and including

3168-503: The older definition of the beginning of the Quaternary Period; many time scales show this division. However, there was a movement amongst geologists (particularly marine geologists ) to also include ongoing geological time (Quaternary) in the Neogene, while others (particularly terrestrial geologists) insist the Quaternary to be a separate period of distinctly different record. The somewhat confusing terminology and disagreement amongst geologists on where to draw what hierarchical boundaries

3234-494: 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

3300-788: The outer-rise region, along with larger tsunami earthquakes occurring at the shallow region of the plate interface (megathrust events) . In 1980, lipids samples were taken via sediment cores located on both the landward and distal sides of the Japan Trench during six sections of the Deep Sea Drilling Project's transect. They were analyzed using gas chromatography and computerized-gas chromatography-mass spectrometric data. Samples were identified to contain many components such as aliphatic and aromatic hydrocarbons, ketones, alcohols, acids and other poly functional components. These components are considered as indicators for terrestrial, marine (non-bacterial), and bacterial inputs within

3366-628: The periods are more closely comparable to the duration of periods in the Mesozoic and Paleozoic Eras. The International Commission on Stratigraphy (ICS) once proposed that the Quaternary be considered a sub-era (sub-erathem) of the Neogene, with a beginning date of 2.58 Ma, namely the start of the Gelasian Stage . In the 2004 proposal of the ICS, the Neogene would have consisted of the Miocene and Pliocene Epochs. The International Union for Quaternary Research (INQUA) counterproposed that

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3432-501: The reptilian genera Langstonia and Barinasuchus , terrestrial predators that were the last surviving members of Sebecosuchia , a group related to crocodiles. The oceans were dominated by large carnivores like megalodons and livyatans , and 19 million years ago about 70% of all pelagic shark species disappeared. Mammals and birds continued to be the dominant terrestrial vertebrates, and took many forms as they adapted to various habitats. An explosive radiation of ursids took place at

3498-412: 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

3564-411: 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

3630-622: The rocks deposited during the Neogene Period . The continents in the Neogene were very close to their current positions. The Isthmus of Panama formed, connecting North and South America . The Indian subcontinent continued to collide with Asia , forming the Himalayas . Sea levels fell, creating land bridges between Africa and Eurasia and between Eurasia and North America. The global climate became more seasonal and continued an overall drying and cooling trend which began during

3696-518: The same cultures further supported the phylogenetic results observed. The discovery of different bacterial domains in these sediments can be used as indicators for microbial diversity found within the Japan Trench. Neogene The Neogene ( / ˈ n iː . ə dʒ iː n / NEE -ə-jeen , ) is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period 23.03 million years ago ( Mya ) to

3762-417: The sediment deposits as a geologic record of past large earthquakes by indicating the change in sediment deposition through sediment gravity flow . The small deep-sea basins with high sedimentation rates found along the Japan Trench pose favorable environmental conditions for the studying of turbidite paleoseismology . During an exploration to the Japan Trench on January 1, 1999, a sample of deep-sea sediment

3828-616: The sediment of the Japan Trench. Expedition 343 of the Japan Trench Fast Driling Project was conducted under the supervision and authority of the Japan Agency For Marine-Earth Science and Technology ( JAMSTEC ). The drilling occurred during two periods; April 1 to May 24, 2012, and from July 5th-18th, 2012. Their main goal was to better understand the very large fault slip of 30–50 metres (98–164 ft) that occurred during

3894-416: 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

3960-400: 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

4026-560: The table to the right, occurring in the years 1938, 1989, 1992, 2005, 2008, 2008 and 2011. Ocean bottom seismometers placed in the base of the Japan Trench measures the ground for any motion created by recording the seismic waves emitted. In 2012, the National Research Institute for Earth Science and Disaster Resilience (NIED) stationed in Tokyo started the construction of seismic and tsunami observation networks along

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4092-460: The trench spanning an area of about 450 km (280 mi) long and 150 km (93 mi) wide resulted here. It is considered as the most powerful earthquake ever recorded in Japan as well as one of the four most powerful earthquakes ever recorded since the start of modern record-keeping in 1900. This megathrust earthquake caused giant tsunami waves to form which eventually caused destruction to

4158-404: The trench. They planned to layout 154 stations about 30 km (19 mi) apart, each equipped with an accelerometer to observe seismic changes and a water pressure gauge for tsunami observation. On March 11, 2011, a magnitude 9.0 earthquake occurred on the subduction interface boundary of the Pacific plate sinking underneath Japan along the Japan Trench. A rupture within the central region of

4224-582: 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

4290-529: Was recorded in Sanriku-oki that may have been triggered by the slow slip observed earlier. Many other earthquakes have been recorded from interplate and transient postseismic slip data along the Japan Trench. Dates include August 2005, May 2008, July 2008, and March 2010 ranging in magnitudes 7.2, 7.0, 6.9, and 6.7 respectively. A characteristic earthquake (~M7) periodically occurred at a recurring interval rate of about 37 years. ~M7 earthquakes can be seen in

4356-514: Was taken from a depth of 6,292 metres (20,643 ft) from the use of a pressure-retaining sediment sampler. Samples from the expedition showed that the microbial diversity displayed a wide distribution of types in the Bacteria domain. 16S ribosomal RNA genes were amplified through the use of polymerase chain reaction (PCR) to determine the nucleotides and identify the bacteria phylogenetically . Further analysis of fatty acids extracted from

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