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44-641: The Chilean Lake District is a zone in Southern Chile defined by its many lakes in the Andean foothills . The term is primarily used in tourism literature and advertising, in Chile Zona Sur is preferred as a geographical concept. The Chilean Lake District includes the cities of Temuco , Villarrica , Pucón , Valdivia , Osorno , Entre Lagos (Puyehue), Puerto Octay , Frutillar , Puerto Varas and Puerto Montt . All lakes drain ultimately to

88-500: 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 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

132-603: A backdrop to clear blue or even turquoise waters, as at Lago Todos los Santos . The rivers that descend from the Andes rush over volcanic rocks, forming numerous white-water sections and waterfalls. Some sections still consist of old-growth forests, and in all seasons, but especially in the spring and summer, there are plenty of wildflowers and flowering trees. The pastures in the northernmost section, around Osorno , are well suited for raising cattle; milk, cheese, and butter are important products of that area. All kinds of berries grow in

176-405: 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 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

220-582: 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

264-489: A fault plane, where it becomes locked, are called asperities . Stress builds up when 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

308-408: 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

352-427: 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 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

396-588: A long-term ENE-WSW shortening. This shortening is accommodated by strike-slip faults . The details of this pattern show significant local variations. The climate of Southern Chile is rainy with a Mediterranean precipitation pattern . The windward slopes of the Chilean Coast Range and the Andes receive up to 3000–5000 mm of precipitation annually. Behind the Chilean Coast range there

440-484: A major fault. Synthetic faults dip in the same direction as the major fault while the antithetic faults dip in 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

484-400: 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 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

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528-421: 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, 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

572-464: 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 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

616-422: 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 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

660-598: Is a weak rain shadow while behind the Andes, in Argentina, precipitation drops sharply. The zone lies in the mid-latitudes and is strongly influenced by the Westerlies . During the summer the South Pacific High moves into the area. The main agricultural soils are; red clay soil ( rojo arcillosos , ultisols ), trumao and ñadi . Some red clay soils are planted with Eucalyptus globulus . In

704-423: 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 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

748-544: 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 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

792-756: Is mainly the Valdivian temperate rainforests . These forests are characterized by large trees, chiefly evergreen Nothofagus and Conifers plus Myrtles . The understory is made of vines , hanging vines , bushes, small trees, moss , dead trunks and decomposing matter. Despite being largely evergreen the Valdivian temperate rainforests do contain a number of deciduous tree species like Nothofagus obliqua and Nothofagus alpina . Other vegetations types of southern Chile include Fitzroya forests, Araucaria forests and wetlands called ñadis . A number of small mammals inhabit Southern Chile including

836-543: 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

880-492: Is particularly clear in the case of detachment faults and major thrust faults . The main types of fault rock include: In geotechnical engineering , 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

924-425: 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 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,

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968-762: 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 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

1012-548: The Calle-Calle River , which flows by the city of Valdivia ) are the only ones in the whole country that are navigable for any stretch. The Central Valley's southernmost portion is submerged in the ocean and forms the Golfo de Ancud . Isla de Chiloé , with its rolling hills, is the last important elevation of the coastal range of mountains. The lakes in this region are remarkably beautiful. The snow-covered Andes form

1056-605: The Pacific Ocean . In the north to Toltén River collects the water of Villarrica , Caburgua and Colico . South of these lakes lie the Seven Lakes whose waters reach the Pacific through Valdivia River . Bueno River drains the water of Ranco , Maihue , Puyehue and Rupanco lakes. Llanquihue Lake is drained to the Pacific by Maullín River and Petrohué River does the same for Todos los Santos Lake . In

1100-466: The Río Bío-Bío at about 37° south latitude to below Isla de Chiloé at about 43.4° south latitude. In this lake district of Chile, the valley between the Andes and the coastal range is closer to sea level, and the hundreds of rivers that descend from the Andes form lakes, some quite large, as they reach the lower elevations. They drain into the ocean through other rivers, some of which (principally

1144-691: The occupation of the Araucania . Spanish is widely spoken in all the region, but the southern people speak a bit slower than Santiaguinos. In the Araucanía region, the Mapudungun is used in rural communities, especially between elders. German is widely spoken in the region because of German colonization, but mostly as a second or third language. 39°19′48″S 72°20′20″W  /  39.33000°S 72.33889°W  / -39.33000; -72.33889 Strike-slip fault In geology ,

1188-536: The pudú , coypu and Darwin's fox . At the time of the Spanish arrival beans, maize and potatoes are known to have been cultivated in Valdivia and around Bueno River . The cultivation of beans extended likely all the way south to Chiloé Archipelago . Southern Chile was during the time of Spanish conquest and colony populated by indigenous Mapuches from Toltén River northwards and by Huilliches south of

1232-657: The seismic shaking and tsunami hazard to infrastructure and people in 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

1276-474: The area, some of which are exported, and freshwater farming of various species of trout and salmon has developed, with cultivators taking advantage of the abundant supply of clear running water. The lumber industry is also important. A number of tourists, mainly Chileans and Argentines, visit the area during the summer. In terms of tectonics at Zona Sur the South American Plate is experiencing

1320-403: The brittle upper crust reacts by fracture – instantaneous stress release – resulting in motion along 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

1364-436: 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 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

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1408-456: The fault and of the presence and nature of any mineralising fluids . Fault rocks are classified by their textures and 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

1452-402: The fault concerning the other side. In measuring the horizontal or vertical separation, the throw of 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

1496-576: 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 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

1540-401: 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 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

1584-427: 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 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

1628-475: 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 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

1672-455: The middle course of Bío Bío River , in the northern part of Zona Sur, soils are sandy with a coarsening trend towards the Andes. Soils of the Chilean Coast Range are mostly derived from metamorphic rock . These soils are usually poor in phosphorus, potassium and have toxic levels of aluminium. Often, these soils have poor drainage and their thickness is highly variable even at scale of tens of meters. The natural vegetation of Southern Chile

1716-500: 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 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,

1760-412: 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

1804-524: The river, both groups are classified as Araucanian. The mountainous zones in the east were populated by Pehuenches Puelches . Until the Battle of Curalaba and the following Destruction of Seven Cities around 1600 the southern zone was part of the General Captaincy of Chile and Spanish Empire. After 1600, the Spanish settlements were destroyed or abandoned with the exception of Valdivia that

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1848-468: 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 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

1892-570: The west large lakes end in terminal moraines and fluvioglacial deposits that are made up of boulders and gravel . The lakes formed in the Quaternary period by glacier erosion . Towards the Andes some lakes have a continuation as U-shaped valleys . Zona Sur Although many lakes can be found in the Andean and coastal regions of central Chile , the south (Sur de Chile) has the country's most lakes. Southern Chile stretches from below

1936-404: Was re-founded in 1645 with heavy fortifications. The zone between Valdivia and Chiloé was gradually incorporated into Chile by a series of agreements with local Huilliches and founding of settlements. By 1850, this process was culminated with the immigration of thousands of German immigrants to Valdivia, Osorno and Llanquihue. The zone north of Valdivia was incorporated into Chile in the 1880s during

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