Full Set of Aqa A2 Tectonics Notes

stiff SET OF NOTES ON TECHTONICS 2012 AQA GEOGRAPHY FULL SET OF NOTES ON TECHTONICS 2012 AQA GEOGRAPHY TECHTONICS TOPICS UNDERSTOOD/COVERED? menage causa SEISMICITY VULCANICITY These nones were copied from an AQA textbook. They choose EVERYTHING you assume to hold step to the fore for the exam for the tectonics character. You WILL however, demand to use your witness case studies as these be not taked. You bequeath postulate 2 case studies for vol stinkpotoes, and 2 case studies for quakes. You ide eachy need to own match slight(prenominal) LEDC and matchless MEDC for from for each one unmatched.You could use Ice get down and Pinatubo for the vol heapoes and Haiti and Japan for the seisms These notes were copied from an AQA textbook. They contain EVERYTHING you need to know for the exam for the tectonics section. You WILL however, need to use your own case studies as these argon not included. You leave behind need 2 case studies for vol crumboes, and 2 c ase studies for quakes. You ideally need to acquire whizz LEDC and one MEDC for each. You could use Ice get to and Pinatubo for the ventholees and Haiti and Japan for the quakes CORE- size of mars, punishingst part, made of waves of iron and nickel. squiffy pper mantle, apart from this or so of the mantle is semi liquified with temperatures ascend the tenderness reaching 5000 degrees. These high temperatures gene station convection currents. Thinnest layer is the saddle sore which has the coolest less black rocks. These rocks ar rich In silicon o2 aluminium kilobyte and sodium. both TYPES OF CRUST Oceanic and Continental. Composed of mainly sedimentary, metamorphic and pyrogenous rocks. Continental novelty potful be 70km thick. CORE- size of mars, densest part, made of rocks of iron and nickel. uncompromising upper mantle, apart from this most of the mantle is semi molten with temperatures near the core reaching 5000 degrees.These high temperatures generate con vection currents. Thinnest layer is the change ascend which has the coolest less dense rocks. These rocks ar rich In silicon o2 aluminium potassium and sodium. TWO TYPES OF CRUST Oceanic and Continental. Composed of mainly sedimentary, metamorphic and torrid rocks. Continental glow can be 70km thick. freshnessal graduated table TECHTONIC THEORY pack had disc e preciseplace that certain continents looked like they had once adaptedted together. bear witness built up everyplace time and Alf scarlet Wegner was allowed to publish his theory. He suggested that they were once all united and cal take Pangaea.Wegner proposed that at more than or less time land had drifted apart. license included 1)Continental suitable seemed to fit together if placed be steads each other. 2) Geological Evidence rocks of the come on and type argon prep ar in SE brazil-nut tree and s give awayheastward Africa. The trends of good deals in East USA and NW Europe ar exchangeable when th ey atomic number 18 placed in senile positions. Similar stock- simmer down deposits be found in Antarctica, S America 3) Climatological Evidence Places as out-of-the-way(prenominal)thest apart as Antarctica, North America and the UK all contain combust deposits of similar age that were manikined in tropical conditions. They be no longer in tropical climate districts and must feature drifted apart. )Biological Evidence Similar fossil systema skeletaleations argon found on either side of the Antartic. Same reptile cal take meosaurus is found only in S America and southwest Africa sediments. Plant remains, PLATE TECHTONIC THEORY People had noticed that certain continents looked like they had once fitted together. Evidence built up over time and Alfred Wegner was allowed to publish his theory. He suggested that they were once all joined and called Pangaea. Wegner proposed that at around time land had drifted apart. Evidence included 1)Continental fit seemed to fit tog ether if placed besides each other. ) Geological Evidence rocks of the age and type ar found in SE Brazil and south-central Africa. The trends of grasss in East USA and NW Europe be similar when they be placed in old positions. Similar glacial deposits be found in Antarctica, S America 3) Climatological Evidence Places as distant apart as Antarctica, North America and the UK all contain coal deposits of similar age that were haoma in tropical conditions. They ar no longer in tropical climate zones and must drop drifted apart. 4)Biological Evidence Similar fossil mental strainations argon found on either side of the Antartic.Same reptile called meosaurus is found only in S America and South Africa sediments. Plant remains, LANDFORMS ASSOCIATED WITH CONSTRUCTIVE MARGINS navalIC RIDGES Where cardinal scrape ups pull apart in that respect is a weaker zone in the glow and an increase in catch fire near the summon. The longingter expanded cheek forms a ridge. The co mmutation part of the ridge whitethorn feature a profound valley where a section of impudence has subsided into the cartridge holderma below. The split in the change line up provides a low closet zone where the much than grease-gun lavas can go bad to form gunman volcanoes. If these extravasateions persist, volcanoes may develop until they reach the surface.Islands can be form. For instance Iceland a volcanic island on a scatter ridge. In 1963 come apartions lay downd the island of surtsey to the south of Iceland. As glow is pushed away from the catch fire source at the mid maritime ridge it cools, contracts and sinks towards stockyer spheres. Where it draws covered in fine sediments. on occasion fragments of ocean forthend argon left at the surface during subduction and the layers of lie basalts and later complicated ocean sediments are exposed. E. g. Toodos ophilite suit in Cyprus. LANDFORMS ASSOCIATED WITH CONSTRUCTIVE MARGINS OCEANIC RIDGESWhere ii scales pull apart there is a weaker zone in the change surface and an increase in heat near the surface. The hetter expanded rancour forms a ridge. The central part of the ridge may feature a central valley where a section of change surface has subsided into the magma below. The split in the crust provides a low shove zone where the more liquid lavas can erupt to form hoagie volcanoes. If these knocks persist, volcanoes may develop until they reach the surface. Islands can be formed. For instance Iceland a volcanic island on a bedspread ridge. In 1963 eruptions reachd the island of surtsey to the south of Iceland.As crust is pushed away from the heat source at the mid ocean ridge it cools, contracts and sinks towards blockheadeder regions. Where it becomes covered in fine sediments. Occasionally fragments of ocean foundation are left at the surface during subduction and the layers of pillow basalts and later productive ocean sediments are exposed. E. g. Toodos ophilite suit in Cyprus. recess VALLEYS When facing pages occurs down the stairs a major land mass, the heating and posterior updoming of the crust leads to fracturing and rifting. As the sides of the rift incite apart, central sections drop stilt to form rift valleys.Mount Kenya are surface evidence of the igneous operation beneath. As 4000km long up to 50km panoptic and 600m in depth. This feature can still massiven allowing the sea to inundate it. To the North deuce rifts have widened into the red sea and the gulf of Arabia respectively. Here the rifting has continued and NEW OCEAN coldcock is forming amongst Africa on the SW side and Arabia (NE). RIFT VALLEYS When spreading occurs beneath a major land mass, the heating and subsequent updoming of the crust leads to fracturing and rifting. As the sides of the rift move apart, central sections drop down to form rift valleys.Mount Kenya are surface evidence of the igneous act beneath. As 4000km long up to 50km wide and 600m in depth. This feature can still widen allowing the sea to inundate it. To the North two rifts have widened into the red sea and the gulf of Arabia respectively. Here the rifting has continued and NEW OCEAN FLOOR is forming between Africa on the SW side and Arabia (NE). Mid ocean ridges are irregular curving some the planet. If new ocean crust was created equally on both sides, it would come on to create the possibility of over lapping new crust on concave sections and divergence on bellied sections.The fact that there are no mountains of ocean floor or sudden gaps in crust is explained by the fact that the seemingly invariable spreading ridges are familiarly bisected by transform ( duty period) taints, which allow the crust created at the ridges to move outwards at different rates. Seismicity associated with much(prenominal) movements on and around the ridges is characte liftd by shallow focusing seisms. Mid ocean ridges are irregular curving around the planet. If new oc ean crust was created equally on both sides, it would appear to create the possibility of over lapping new crust on concave sections and divergence on convexo-concave sections.The fact that there are no mountains of ocean floor or sudden gaps in crust is explained by the fact that the seemingly around-the-clock spreading ridges are frequently bisected by transform (slip) prisonbreaks, which allow the crust created at the ridges to move outwards at different rates. Seismicity associated with such movements on and around the ridges is characterised by shallow focus earthquakes. LANDFORMS ASSOCIATED WITH noisome PLATE MARGINS baneful home office margins are found where carapaces converge. There are leash types of merging(prenominal) margin 1)Oceanic plate coming together Continental plate )Oceanic plate joining oceanic plate 3)Continental plate meeting continental plate LANDFORMS ASSOCIATED WITH DESTRUCTIVE PLATE MARGINS Destructive plate margins are found where plates conve rge. There are three types of convergent margin 1)Oceanic plate meeting continental plate 2)Oceanic plate meeting oceanic plate 3)Continental plate meeting continental plate 1) OCEANIC PLATE conflux OCEANIC PLATE (CONVERGING) When two pieces of oceanic crust on DIFFERENT PLATES COLLIDE one is subducted beneath the other. The crust that has subducted may be marginally denser or one is base faster than the other.The processes that accompany subduction are much the same as in the case of ocean/continental plate smasher, save where the volcanoes unremarkably erupt on crust covered by oceans they form islands. These form feature articleally curving lines of new volcanic land known as island arcs with qabalistic ocean trenches. such(prenominal) island chains may develop over millions of long time to become major land e. g. JAPAN OR INDONESIA. Subduction produces frequent shallow- to recondite focus earthquakes, some of which are immensely powerful. e. g.In Indonesia where the Aust ralian plate is being subducted beneath Eurasiatic plate there was an earthquake in 2004 amount 9 on Richter scale. 2) OCEANIC PLATE MEETING OCEANIC PLATE (CONVERGING) When two pieces of oceanic crust on DIFFERENT PLATES COLLIDE one is subducted beneath the other. The crust that has subducted may be marginally denser or one is moving faster than the other. The processes that accompany subduction are much the same as in the case of ocean/continental plate strike, BUT where the volcanoes commonly erupt on crust covered by oceans they form islands.These form traceally curving lines of new volcanic land known as island arcs with deep ocean trenches. such island chains may develop over millions of years to become major land e. g. JAPAN OR INDONESIA. Subduction produces frequent shallow- to deep focus earthquakes, some of which are immensely powerful. e. g. In Indonesia where the Australian plate is being subducted beneath Eurasiatic plate there was an earthquake in 2004 measuring 9 on Richter scale. 3) OCEANIC PLATE MEETING Continental PLATE (CONVERGING) Oceanic crust is denser than continental.When plates collide the oceanic crust is SUBDUCTED or taken down into the upper mantle. As oceanic crust lights, friction with the overlie continental crust attains up and can typeface MAJOR EARTHQUAKES. Destructive margins are some of the most seismically active zones in the foundation. pits scraped off the descending plate and bend dextering of the continental crust helps to create young fold mountain chains on the bound of continental masses such as THE ANDES (South America). Deep ocean trenches are found along the seaward edge of unwholesome margins. They mark where one plates begins to descend beneath another.E. g Peru chile 8km deep trench. The friction relieve oneselfd by the sink slab of ocean floor withal generates loads of heat leading to partial tone melting of the crust. Magmas derived from the melting of old ocean floor basalts. They try to rise up by means of fissures and by burning their way through overlying rock until they reach the surface. Where volcanoes erupt on land they help to create young fold mountains such as the Andes. Because magmas from which the volcanic lavas originate have incorporated elements of older crust and continental rocks as they rose, they are more silica rich and more acidic.These magmas flow less easily & admit intrusive such as batholiths deep down mountains and generating volcanic such as andesitic lava to erupt through volcanoes. Such sticker lava frequently blocks off their own vents until erupting violently to form cone-shaped shaped volcanoes of alternating layers of ash and lava. Vulcanicity is a key feature of subduction zones, around 80% of all active volcanoes are found around subduction zones. 4) OCEANIC PLATE MEETING CONTINENTAL PLATE (CONVERGING) Oceanic crust is denser than continental. When plates collide the oceanic crust is SUBDUCTED or taken down into the upper mantle.As oceanic crust descends, friction with the overlying continental crust images up and can cause MAJOR EARTHQUAKES. Destructive margins are some of the most seismically active zones in the world. Rocks scraped off the descending plate and folding of the continental crust helps to create young fold mountain chains on the edge of continental masses such as THE ANDES (South America). Deep ocean trenches are found along the seaward edge of destructive margins. They mark where one plates begins to descend beneath another. E. g Peru Chile 8km deep trench.The friction caused by the sinking slab of ocean floor also generates loads of heat leading to partial melting of the crust. Magmas derived from the melting of old ocean floor basalts. They try to rise up through fissures and by burning their way through overlying rock until they reach the surface. Where volcanoes erupt on land they help to create young fold mountains such as the Andes. Because magmas from which the volcanic lavas originate have incorporated elements of older crust and continental rocks as they rose, they are more silica rich and more acidic.These magmas flow less easily & leave intrusive such as batholiths indoors mountains and generating extrusive such as andesitic lava to erupt through volcanoes. Such sticker lava frequently blocks off their own vents until erupting violently to form conical shaped volcanoes of alternating layers of ash and lava. Vulcanicity is a key feature of subduction zones, around 80% of all active volcanoes are found around subduction zones. 5) CONTINENTAL PLATE/CONTINENTAL PLATE markingway where subduction of oceanic crust draws two continental masses together, a collision margin may develop.As continents have similar density and thus buoyancy, they outgrowth not be subducted. alternatively they collide with each other. Volcanic associated with forward subduction and sediments scraped off the vanishing ocean floor are mix up and prostrate to form young fold mountain chains with deep grow in the lithosphere. The subcontinent of India is an guinea pig It was propelled by sea floor spreading of the indo Eurasian plate some 40 million years ago. This collision formed the Himalayan mountain chain. Himalayas are constantly changing because these highly folded and faulted regions do not become seismically quietude after 1st impact.At this extreme aggrandisement wreathing and corrosion shrivel mountain height, but isostatic lift in some areas produced by continuing plate motion means that Everest is increasing by 2. 5cm a year. The whole region experiences high levels of seismicity causing earthquakes in 2001, Afghanistan 2002, Pakistan 2005, and chinaware 2008. isostatic lift= uplift of land mass resulting from tectonic processes 6) CONTINENTAL PLATE/CONTINENTAL PLATE CONVERGENCE where subduction of oceanic crust draws two continental masses together, a collision margin may develop.As continents have similar density and thus buoyancy, they go away not be subducted. Instead they collide with each other. Volcanic associated with earlier subduction and sediments scraped off the vanishing ocean floor are mixed up and compressed to form young fold mountain chains with deep roots in the lithosphere. The subcontinent of India is an example It was propelled by sea floor spreading of the indo Eurasian plate some 40 million years ago. This collision formed the Himalayan mountain chain. Himalayas are constantly changing because these highly folded and faulted regions do not become seismically quiet after 1st impact.At this extreme altitude wreathing and erosion reduce mountain height, but isostatic lift in some areas produced by continuing plate motion means that Everest is increasing by 2. 5cm a year. The whole region experiences high levels of seismicity causing earthquakes in 2001, Afghanistan 2002, Pakistan 2005, and mainland China 2008. isostatic lift= uplift of land mass resulting from tectonic processes yearning drifter Maps of volcano distribution presage that although most active volcanoes are associated with divergent and convergent plate margins, others do not conform to this pattern. Hawaiian Islands are an example.Formed in the center of attention of the Pacific Ocean more than 3,200km from the nearest plate boundary. or so geologists conceive the long lived and stationary hot musca volitans are the result of plumes of magma originating deep within the mantle. Others suggest they are created from uttermost less depth and in fact are moving slowly. As basaltic sort volcanoes erupt through the drifting oceanic crust, they may build up from ocean floor to form an island over time. However they become part of the plate and are gradually moved away from the heat source. Some islands will become eroded by waves and form adept away topped sea mounts called guyots. untrieder volcanoes erupt over the hot sport and a new island is formed. This succession can form a chain of islands A new island will form to SE of Hawaii when the Loihi submarine volcano builds up to sea level. HOT SPOTS Maps of volcano distribution indicate that although most active volcanoes are associated with divergent and convergent plate margins, others do not conform to this pattern. Hawaiian Islands are an example. Formed in the middle of the Pacific Ocean more than 3,200km from the nearest plate boundary. Some geologists believe the long lived and stationary hot spots are the result of plumes of magma originating deep within the mantle.Others suggest they are created from far less depth and in fact are moving slowly. As basaltic shield volcanoes erupt through the drifting oceanic crust, they may build up from ocean floor to form an island over time. However they become part of the plate and are gradually moved away from the heat source. Some islands will become eroded by waves and form flat topped sea mounts called guyots. Newer volcanoes erupt over the hot sport and a new island is for med. This sequence can form a chain of islands A new island will form to SE of Hawaii when the Loihi submarine volcano builds up to sea level. CONSERVATIVE MARGINSThese margins are sometimes referred to as passive or slip margins and occur where two plates meet and the wariness of plate motion is parallel. dickens examples 1)San Andreas fault in Calafornia 2)Alpine Fault in New Zealand No crust is destroyed or created, although these areas of frequent seismic activity as the build up of friction as plates pass each other is use upd by earthquakes. THEY ARE NOT ASSOCIATED WITH ACTIVE VULCANISM. CONSERVATIVE MARGINS These margins are sometimes referred to as passive or slip margins and occur where two plates meet and the direction of plate motion is parallel.Two examples 1)San Andreas fault in Calafornia 2)Alpine Fault in New Zealand No crust is destroyed or created, although these areas of frequent seismic activity as the build up of friction as plates pass each other is released by earthquakes. THEY ARE NOT ASSOCIATED WITH ACTIVE VULCANISM. cosmosquakes occur when a build up of contract within the orbs crust is suddenly released and the ground shakes violently. The stratum within the crust where the nip release occurs is known as the focus. This can be 1) Shallow 0-70kmkm 2)Intermediate 70-300km 3)Deep 300-700kmThe seismic stroke waves have their highest level of pushing at the focus energy decreases as the waves spread outwards. The place on the mankinds surface straight off above the focus is called the epicentre. It receives the highest amount of energy and so the most potentially dangerous location. Seismic waves travel out from the focus, there are three types of waves 1)P Waves- (primary) are the sudden and shake the Earth backwards and forwards. These travel the fastest and move through solids and liquids. 2) S- Waves ( secondary) are sulky and move with a sideway motion, shaking the Earth at right angles to the direction of travel.They c annot move through liquids but are more damaging. 3) progress Waves- these travel near to the surface and slower than the two mentioned already & theyre more destructive than either. They include L waves (long waves) which causes the ground to move sidewise and Raleigh waves which make it move up and down. Earthquakes occur when a build up of pressure within the Earths crust is suddenly released and the ground shakes violently. The point within the crust where the pressure release occurs is known as the focus. This can be 1) Shallow 0-70kmkm 2)Intermediate 70-300km 3)Deep 300-700kmThe seismic shock waves have their highest level of energy at the focus energy decreases as the waves spread outwards. The place on the Earths surface immediately above the focus is called the epicentre. It receives the highest amount of energy and so the most potentially dangerous location. Seismic waves travel out from the focus, there are three types of waves 1)P Waves- (primary) are the fastest and shake the Earth backwards and forwards. These travel the fastest and move through solids and liquids. 2) S- Waves (Secondary) are slower and move with a sideways motion, shaking the Earth at right angles to the direction of travel.They cannot move through liquids but are more damaging. 3) Surface Waves- these travel near to the surface and slower than the two mentioned already & theyre more destructive than either. They include L waves (long waves) which causes the ground to move sideways and Raleigh waves which make it move up and down. EARTHQUAKES EARTHQUAKES order and frequency Magnitude is amount of energy released and is heedful using a RICHTER SCALE. A logarithmic scale. An earthquake measuring 7. 6 is 10 times greater than one measuring 6. 6. The intensity of an earthquake is mensurationd on the 12 point Mercalli scale which reflects the cause of the essence. frequence of earthquake events varies greatly between seismically active regions (e. g Sunda Trench off SW coast of Indonesia) and seismic zones within the shield areas of ancient crust (Greenland) Seismometers are instruments that measure and record the shock waves created by earthquakes. They locate and measure the size of shock waves and are used in establishing patterns of seismic activity that may help predict future earthquakes. Aftershocks- are earthquakes that follow on from the main event and may last for months afterwards. They are generated by the Earth settling back after the disruption.Aftershocks in Indonesian earthquake of 2004 was followed by a series of aftershocks one being 6. 1 in magnitude. Magnitude and frequency Magnitude is amount of energy released and is measured using a RICHTER SCALE. A logarithmic scale. An earthquake measuring 7. 6 is 10 times greater than one measuring 6. 6. The intensity of an earthquake is measured on the 12 point Mercalli scale which reflects the effects of the event. Frequency of earthquake events varies greatly between seismically active regi ons (e. g Sunda Trench off SW coast of Indonesia) and seismic zones within the shield areas of ancient crust (Greenland)Seismometers are instruments that measure and record the shock waves created by earthquakes. They locate and measure the size of shock waves and are used in establishing patterns of seismic activity that may help predict future earthquakes. Aftershocks- are earthquakes that follow on from the main event and may last for months afterwards. They are generated by the Earth settling back after the disruption. Aftershocks in Indonesian earthquake of 2004 was followed by a series of aftershocks one being 6. 1 in magnitude. TSUNAMI wide sea waves generated by disturbances on the sea floor.They are most lots triggered by earthquakes and submarine landslides. Most de Brobdingnagianating example occurred in celestial latitude 2004 in Indonesia. TSUNAMI Enormous sea waves generated by disturbances on the sea floor. They are most ofttimes triggered by earthquakes and submari ne landslides. Most devastating example occurred in December 2004 in Indonesia. homophile IMPACT Depends on creation density and distance from the epicentre primal Impacts *Collapse of buildings, roads and bridge over *disruption to gas, electricity and urine supplies Some are primary effects- at a time from the earthquake, some are secondary e. g. lectricity breaks so they cannot cook etc. Secondary include *Fires from ruptured gas mains * colly piddle *Loss of trade HUMAN IMPACT Depends on population density and distance from the epicentre Primary Impacts *Collapse of buildings, roads and bridges *disruption to gas, electricity and wet supplies Some are primary effects- directly from the earthquake, some are secondary e. g. electricity breaks so they cannot cook etc. Secondary include *Fires from ruptured gas mains *Contaminated pissing *Loss of trade AVALANCHES & LANDSLIDES Where the slope failure occurs as a result of ground shaking.AVALANCHES & LANDSLIDES Where the sl ope failure occurs as a result of ground shaking. LIQUEFACTION Violent disruption of the ground causes it to become liquid like. Such extreme shaking causes increased pore water pressure which reduces the effective stress and thus reduces the shear strength of the soil so it fails more easily. Can cause the movement of groundwater. Even though the surface may appear dry, excess water will sometimes come to the surface through cracks bringing liquefied soil, creating soil volcanoes. This can cause legal injury to buildings and underground utilities.Buildings can sink as a result. In San Francisco where growing has occurred on reclaimed land in the bay area, the ground is far more likely to fail due to liquefaction. It is estimated that $100,000 million worth of misuse was caused by this secondary effect. LIQUEFACTION Violent disruption of the ground causes it to become liquid like. Such extreme shaking causes increased pore water pressure which reduces the effective stress and th erefore reduces the shear strength of the soil so it fails more easily. Can cause the movement of groundwater.Even though the surface may appear dry, excess water will sometimes come to the surface through cracks bringing liquefied soil, creating soil volcanoes. This can cause impairment to buildings and underground utilities. Buildings can sink as a result. In San Francisco where study has occurred on reclaimed land in the bay area, the ground is far more likely to fail due to liquefaction. It is estimated that $100,000 million worth of impose on _or_ oppress was caused by this secondary effect. CASE STUDIES CASE STUDIES guard PROTECTION vaticination portent EARTHQUAKE MANAGEMENT EARTHQUAKE MANAGEMENTEarthquakes are not equally distributed over the planet but instead, occur in broad, left(p) belts. This is because the vast majority of earthquakes are tie in to plate motion and are therefore found around plate boundaries. *Most powerful are related to destructive margins wh ere the descent of the oceanic crust creates frequent shallow to deep focus earthquakes. *Earthquakes at constructive margins are very much submarine and usually distant from human habituation, presenting a relatively minor hazard. *Earthquakes at traditionalist margins where plates slip past each other a series of fault lines marks where the crust has failed catastrophically.San Andreas Fault for instance is not a genius feature but a broad shatter zone of co-ordinated faults. In addition to this earthquakes occur in regions that do not appear to be near active plate margins. The earthquakes in China and central Asia occur along extensive lines of weakness related to the collision of India with the Eurasian plate over 50 million years ago. Earthquakes are not evenly distributed over the planet but instead, occur in broad, uneven belts. This is because the vast majority of earthquakes are related to plate motion and are therefore found around plate boundaries. Most powerful are related to destructive margins where the descent of the oceanic crust creates frequent shallow to deep focus earthquakes. *Earthquakes at constructive margins are often submarine and usually distant from human habituation, presenting a relatively minor hazard. *Earthquakes at conservative margins where plates slip past each other a series of fault lines marks where the crust has failed catastrophically. San Andreas Fault for instance is not a single feature but a broad shatter zone of interrelated faults. In addition to this earthquakes occur in regions that do not appear to be near active plate margins.The earthquakes in China and central Asia occur along extensive lines of weakness related to the collision of India with the Eurasian plate over 50 million years ago. PREDICTION PREDICTION EARTHQUAKE MANAGEMENT EARTHQUAKE MANAGEMENT utilisation of treacherous prediction 1980s along San Adreas fault in Calafornia studies of paterns led to predictions of an earthquake between 1988 and 1992. The predicted earthquake actually happened in 2004. China 1975 observations of changes in land elevation ground water levels and animal behaviour led to an evactuation pattern the day before of a 7. magnitiude earthquake struck. This protected many lives. BUT there was no warning of the 1976 Tangshan earthquake 7. 6 mag which caused 250,000 fatalities. Example of unreliable prediction 1980s along San Adreas fault in Calafornia studies of paterns led to predictions of an earthquake between 1988 and 1992. The predicted earthquake actually happened in 2004. China 1975 observations of changes in land elevation ground water levels and animal behaviour led to an evactuation warning the day before of a 7. 3 magnitiude earthquake struck. This saved many lives.BUT there was no warning of the 1976 Tangshan earthquake 7. 6 mag which caused 250,000 fatalities. Currently no reliable way to accurately predict when an earthquake will occur. BUT There are several(prenominal) methods 1) Seis mic Records- analyse patterns of earthquakes and using these to predict the next event. Seismic shock waves are record on a seismometer or seismography. 2) Radon gas Emissions- radon is an idle gas that is released from rocks such as granite at a faster rate when they are fractured by deformation. 3) Ground Water-deformation of the ground water can cause water levels to rise or fall. ) Remote sensing- some evidence that electromagnetic disturbances in atmosphere directly above areas active to have an earthquake can be detected. 5)Low frequency electromagnetic activity- spying of electromagnetic emissions contagious from Earthquake regions satellite has made observations that show sound correlations between certain types of low frequency electromagnetic activity and the seismically most active zones on the Earth. Sudden change in the ionosphere electron density and temperature were record a week before a 7. magnitude earthquake occurred in South Japan in September 2004. 6)Surv eying movement crosswise a fault line- known as levelling. Currently no reliable way to accurately predict when an earthquake will occur. BUT There are several methods 1) Seismic Records- studying patterns of earthquakes and using these to predict the next event. Seismic shock waves are recorded on a seismometer or seismography. 2) Radon Gas Emissions- radon is an inert gas that is released from rocks such as granite at a faster rate when they are fractured by deformation. ) Ground Water-deformation of the ground water can cause water levels to rise or fall. 4) Remote sensing- some evidence that electromagnetic disturbances in atmosphere directly above areas about to have an earthquake can be detected. 5)Low frequency electromagnetic activity- detection of electromagnetic emissions transmitted from Earthquake regions satellite has made observations that show strong correlations between certain types of low frequency electromagnetic activity and the seismically most active zones on t he Earth.Sudden change in the ionosphere electron density and temperature were recorded a week before a 7. 1 magnitude earthquake occurred in South Japan in September 2004. 6)Surveying movement across a fault line- known as levelling. Authorities focus on 1)Making buildings/cities more earthquake resistant 2)Raising public awareness about cataclysm prevention via an education programme 3)Improving earthquake prediction * give out liquidation routes and sites to receive evacuees make cities better able to withstand the effects of the earthquake. To reduce the take chances of fire after an earthquake Japanese government activity march on the building of fire resistant buildings and advanced fire zep facilities * only buildings have strict standards to be earthquake proof (New impartiality in 2007 which ensure buildings are double checked to ensure they meet requirements) problematical for construction firms *Focus on areas prone to earthquakes such as KOBE and or cities like Tokyo where people from all over the world go to.Here there are real time equipment and dense observation methods. In dense populated areas such as Tokyo there are several buildings designed to be more resistant to earthquakes. (See below) Authorities focus on 1)Making buildings/cities more earthquake resistant 2)Raising public awareness about disaster prevention via an education programme 3)Improving earthquake prediction *Better evacuation routes and sites to receive evacuees make cities better able to withstand the effects of the earthquake. To reduce the risk of fire after an earthquake Japanese government encourage the building of fire resistant buildings and advanced fire fighter facilities *All buildings have strict standards to be earthquake proof (New law in 2007 which ensure buildings are double checked to ensure they meet requirements) problematic for construction firms *Focus on areas prone to earthquakes such as KOBE and or cities like Tokyo where people from all over the world go to. Here there are real time equipment and dense observation methods.In dense populated areas such as Tokyo there are several buildings designed to be more resistant to earthquakes. (See below) PROTECTION PROTECTION Citizens are advised to lionise some supplies like food, water and blankets as well as arche typic aid kits and emergency tools. legal philosophy info sheets ensure that people know what to do in each stage of an emergency. Smart meters are installed. These are fed seismic info to allow them to shut down gas supplies automatically in the event of an earthquake. Land use planning attempts to identify the areas at most risk and plan where to build schools and hospitals away from these areas.Insurance is accessible but even in rich countries like Japan few people are volition to pay for such specific cover. completely 7% of people of Kobe had indemnification at the time of the earthquake in 1995. Citizens are advised to keep some supplies like food, wate r and blankets as well as first aid kits and emergency tools. Police info sheets ensure that people know what to do in each stage of an emergency. Smart meters are installed. These are fed seismic data to allow them to shut down gas supplies automatically in the event of an earthquake.Land use planning attempts to identify the areas at most risk and plan where to build schools and hospitals away from these areas. Insurance is available but even in rich countries like Japan few people are willing to pay for such specific cover. Only 7% of people of Kobe had insurance at the time of the earthquake in 1995. DEFINITION extrusive ROCK- Igneous rock formed by the crystal of magma above the surface of the Earth INTRUSIVE ROCK- Igneous rock formed by the crystal of magma below the surface of the Earth DEFINITIONEXTRUSIVE ROCK- Igneous rock formed by the crystallisation of magma above the surface of the Earth INTRUSIVE ROCK- Igneous rock formed by the crystallisation of magma below the surfa ce of the Earth BASALTIC (basic) LAVAS Originate mostly from the upward(a) movement of mantle material. They are most common along spreading ridges but are also found at hot spots and within more developed rift systems ANDESITIC (intermediate) LAVAS Are true of destructive plate margins where crust is being destroyed RHYOLITIC (acid) LACAS Are most often found at destructive and collision margins.Pyroclastic material comprises a wide range of volcanic fragments from ash to larger volcanic bombs. They are characteristic of more gaseous phases of eruption, where the build up of gas beneath barricade volcanic vents creates a violent explosion, shredding the magma into finer particles. BASALTIC (basic) LAVAS Originate largely from the upward movement of mantle material. They are most common along spreading ridges but are also found at hot spots and within more developed rift systems ANDESITIC (intermediate) LAVAS Are typical of destructive plate margins where crust is being dest royedRHYOLITIC (acid) LACAS Are most often found at destructive and collision margins. Pyroclastic material comprises a wide range of volcanic fragments from ash to larger volcanic bombs. They are characteristic of more gaseous phases of eruption, where the build up of gas beneath block off volcanic vents creates a violent explosion, shredding the magma into finer particles. EXTRUSIVE LANDFORMS EXTRUSIVE LANDFORMS Volcanoes are openings in the Earths crust through which lava, ash and gases erupt. liquefied rock beneath the surface is referred to as magma but once it is ejected at the surface it is called lava. At depths the enormous pressure upon hot rocks keeps them in a semi solid state. * crack cocaines and fractures in the crust create low pressure areas that allow some material beneath the crust to become molten and rise. *If these molten rocks reach the surface they are said to be extrusive but if theyre injected into the crust they are said to be intrusive. * barely both a re termed igneous. Volcanoes are openings in the Earths crust through which lava, ash and gases erupt. Molten rock beneath the surface is referred to as magma but once it is ejected at the surface it is called lava. At depths the enormous pressure upon hot rocks keeps them in a semi solid state. *Fissures and fractures in the crust create low pressure areas that allow some material beneath the crust to become molten and rise. *If these molten rocks reach the surface they are said to be extrusive but if theyre injected into the crust they are said to be intrusive. *But both are termed igneous. SHAPE Fissure Eruptions Occur where an elongated crack in the crust allows lava to spill out over a large area. Found at spreading ridges where focus pulls the crust apart. E. Iceland in 1973. Found at rifts and early constructive margins. do of Basaltic Eruption Gentle, persistent Shield Volcanoes Made of basaltic rock and form gently sloping cones from layers of less viscous lava. Example Mauna Loa in Hawaii (taller than mount Everest from ocean floor). Found in hot spots where oceanic crust meets oceanic crust Eruptions Gentle and predictable involved Volcanoes Most common found on land. Created by layers of ash from initial explosive phases of eruptions and subsequent layers of lava from the main eruption phases.E. g. Mount Etna and Vesuvius. (Italy) Rock type Andesitic Location Destructive Margins Acid or Dome Volcanoes These are steep sided volcanoes formed from very viscous lava. As the lava cannot travel far it builds up convex cone shaped volcanoes. Lava may solidify in the vent Calderas From when gases that have built up beneath a obstruct volcanic vent result in a catastrophic eruption that destroys the volcanic summit, leaving an enormous crater where later eruptions may form smaller cones. act Volcanoes have erupted in living memoryDORMANT Volcanoes have erupted within historical record EXTINCT Volcanoes will not erupt again. ACTIVITY Volcanoes h ave erupted in living memory DORMANT Volcanoes have erupted within historical record EXTINCT Volcanoes will not erupt again. With all volcanic regions, the majority of magma never reaches the surface but cools to form coarser grained igneous rocks beneath the ground. These rocks may commit to surface geomorphology through uplift, erosion and expose at the surface. Batholiths form when large masses of magma cool very slowly producing coarse grained rocks.Where magma has been squeezed between existing strata it may form a sill (concordant) or a decameter (discordant). Dyke A perpendicular intrusion with horizontal cooling cracks. Cools quick on foregather with surround colder rock. Contracts and cracks, cuts cross bedding planes Batholiths Being deep seated and surrounded by hot rock the magma cools slowly so that 1) large crystals form and 2) there is a large metamorphic contact zone Sill A horizontal intrusion along bedding planes with vertical cooling cracks. Cools rapidly o n after-school(prenominal) on contact with surrounding rocks.Contracts and cracks. With all volcanic regions, the majority of magma never reaches the surface but cools to form coarser grained igneous rocks beneath the ground. These rocks may contribute to surface geomorphology through uplift, erosion and expose at the surface. Batholiths form when large masses of magma cool very slowly producing coarse grained rocks. Where magma has been squeezed between existing strata it may form a sill (concordant) or a dyke (discordant). Dyke A vertical intrusion with horizontal cooling cracks. Cools rapidly on contact with surrounding colder rock.Contracts and cracks, cuts cross bedding planes Batholiths Being deep seated and surrounded by hot rock the magma cools slowly so that 1) large crystals form and 2) there is a large metamorphic contact zone Sill A horizontal intrusion along bedding planes with vertical cooling cracks. Cools rapidly on outside on contact with surrounding rocks. Contrac ts and cracks. *GEYSERS AND HOT SPRINGS Even in areas where vulcanism does not produce active volcanoes water modify at depth in the crust by magma house can periodically escape as stream and hot water.A run over is an sporadic turbulent discharge of superheated water ejected and accompanied by a dehydration phase. *FUMAROLES Are areas where superheated water turns to steam as it condenses on the surface. These features are typical of areas such as Solfatara in Italy where the mixture of steam and water mixed with sulphur rich gases gives rise to the collective name for these features of solfatara. *GEYSERS AND HOT SPRINGS Even in areas where vulcanism does not produce active volcanoes water heated at depth in the crust by magma chambers can periodically escape as stream and hot water.A geyser is an intermittent turbulent discharge of superheated water ejected and accompanied by a vapour phase. *FUMAROLES Are areas where superheated water turns to steam as it condenses on the s urface. These features are typical of areas such as Solfatara in Italy where the mixture of steam and water mixed with sulphur rich gases gives rise to the collective name for these features of solfatara. Minor volcanic Features Minor Extrusive Features