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18 Cards in this Set
- Front
- Back
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Describe the characteristics of oceanic crust (3) |
•Oceanic crust is generally less than 200 million years old – some is muchnewer – a million years old in Iceland. •It is dense and can sink beneathcontinental crust. •Oceanic crust can be renewed at constructive platemargins and destroyed at subduction zones. |
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Describe the world distribution of volcanoes (3) |
•Volcanoes occur in lines, such as along the west coast of North andSouth America. •There are many clustering along the edge of the PacificOcean, especially in/near Japan. •There are small clusters in places suchas Iceland, southern Italy •They tend to follow the plate margins such asin the middle of the Atlantic Ocean where the plates are moving apart ornear Japan where the plates are moving together. `This is not always thecase and some such as Hawaii are a long way from plate margins andoccur relatively isolated. |
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Use a case study to discuss the immediate and long-term responses to a volcaniceruption (8) |
• When Eyjafjallajokull erupted in April 2010, residents had to wear masksto prevent them breathing in the ash from the volcano. •People living nearit had to be evacuated to shelters. They tried to seal their homes from theash and got their cattle inside to protect them. •Much of European airspace was closed as the impacts on jet engines could lead to crashes.This caused chaos as all flights within countries like England werecancelled and passengers were stranded. •When given the all-clear,people went back to their homes and cleared the ash from their homesand farms - and began to plant crops. •The water from melting glaciersthreatened the road going along the south coast – Route 1 – and thiswas saved by the embankment on which the road was built being takenaway to allow the water to pass. •This saved the bridges nearby and wasrebuilt within weeks of the eruption and restored power supplies. •Quickthinking action at the start prevented more serious disruption later andmade the restoration of the link much easier. |
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How is a supervolcano different from a volcano? (2) |
•A supervolcano is much bigger than a volcano – in terms of itsbase/shape and the amount of magma that is erupted – where at least1000 cubic km of material can be erupted – in contrast to Mount StHelens where 1 cubic km was erupted. •It is different in shape as it is sunken in the middle (caldera) rather than coming to a peak. • Supervolcanoeserupt less frequently |
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Describe the likely global consequences of a supervolcano eruption (4) |
• Ash would beemitted into the atmosphere. This would travel away from the volcanowith the wind towards countries like the UK where it would be expected toarrive within 5 days of an eruption. •The ash would reduce the amount ofrays from the Sun that could penetrate and so temperatures would fall •causing a volcanic winter •This would make it difficult to grow enoughfood, crops would fail and it could lead to widespread deaths • (and) peopletrying to emigrate. |
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To what extent is there a relationship between the largest and deadliest earthquakesshown in Figure 1? (3) |
•Only on two occasions out of five does the highest magnitude ofthe year cause the most deaths i.e. in 2011 in Japan and in 2008in China. •Sometimes the magnitude is relatively low but causes alot of deaths as in Haiti in 2010. •There is a limited relationshipbetween the largest and the deadliest earthquakes. |
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Outline one reason why the largest earthquakes do not always cause the most deaths (2) |
•population densitymay be low so few people present in the danger area •some areasmay be poor and so buildings just collapse killing people. |
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What are fold mountains? (2) |
Fold mountains are large ranges of mountains where differentrock layers have crumpled into anticlines and synclines as theyhave pushed together. |
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Use a case study to describe how people use fold mountains (6) |
•Farming – reference to the growing of subsistence crops, such aspotatoes on terraces – steps made to create flat areas. Mostcrops are grown in lower parts of valleys, including some cashcrops such as cotton. Male llamas are used as pack animalswhilst the females are used for meat and milk, and their wool isused for clothes and rugs. •H.E.P. – steep, narrow valleys are suitable for construction ofdams and steep relief gives fast flowing water needed to turn theturbines. Peru has a number of schemes, including Yuncanproject and the El Platinal project that is under construction. •Mining – the Andes are rich in minerals – tin, nickel, silver andgold are all present.Yanacocha gold mine in Peru is the largest in the world and hasled to expansion of the town Cajamarca from 30,000 to 240,000inhabitants. •Tourism – high mountains provide spectacular scenery of highpeaks, valleys, lakes and glaciers. In addition, there are ancientareas of settlement such as Machu Picchu and the Inca Trail – a45km trek in the mountains. |
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With the help of Figure 1, outline differences between constructive and destructiveplate margins (3) |
• Constructive plate margins occur where plates move away from each other – aswith the North American plate and Eurasian plate in the Atlantic Ocean •whereasdestructive plate margins are found where plates move towards each other – asis the case with the Nazca plate and the South American plate. •New crustformed versus destroyed. •Land forms at different plate margins. |
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Give one example of a conservative plate margin shown in Figure 1 (1) |
North American plate and Pacific plate |
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Outline the characteristics of a shield volcano (2) |
• flat/rounded top •low lying •broad base •gently sloping sides •made of runny lava/ basaltic lava • little ash • non-explosive eruption •frequent eruptions |
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Explain the formation of a composite volcano (4) |
•Composite volcanoes occur at destructive plate margins. •Here, plates movetowards each other due to convection currents. •Pressure builds up over a longperiod of time as the denser oceanic plate sinks beneath the continental plate. •Melting of this occurs in the subduction zone due to friction and heat and thecrust becomes magma. •This process causes a build-up of pressure which isreleased in an explosive eruption – giving volcanoes that are formed of stickyslow flowing lava and ash often in alternate layers along a line of weakness/fault. |
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Describe how volcanoes are monitored so that people can prepare for an eruption (4) |
•Earthquakes occurring more frequently or strongly are a sign that an eruption islikely to occur •and this gives warning and time to prepare. •Tiltmeters •recordeven a slight change in the shape of the land and spiders monitor gases – theconcentration of sulphur dioxide increases before an eruption. •Changesidentified in advance allow time for evacuation if necessary or stocking up ofessential supplies. |
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Explain the cause of the Japanese tsunami (3) |
• Recognition of destructive plate margin with epicenter / earthquake originatingunder the ocean. •This resulted in the land being thrown / flexed upwards leadingto displacement of the column of water above. •This separates and heads towardthe coast. •As it approaches, the wave length reduces and the height increasesas the water piles onto the coast. |
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Use a case study to describe the effects of a tsunami (8) |
•The area along the coast to the north of Tokyo was worst affected – stretchingfor over 200 miles. •Closest to the epicentre was Minamisanriku where it isthought that half of its 17 000 population died. •The wave was in excess of 10metres and engulfed entire settlements transporting cars and boats like toys. •In Sendai, these were shifted to the harbour wall, people were stranded in theairport and 5 million did not have power and 1 million had no mains watersupply. •Water flooded the reactors of the Fukushima nuclear plant causing theloss of power, but more worryingly the risk of meltdown as more people had tomove from their homes. |
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Describe the distribution of earthquakes (4) |
•earthquakes occur in linear clusters •many occur on plateboundaries •especially destructive and/or conservative plateboundaries (• with example) • clustering around edge of Pacificplate |
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Draw a labelled diagram(s) to explain why earthquakes occur atconservative plate boundaries (4) |
•Diagram should show plates moving in similar directions (but not thesame) •should label to show sliding past each other •same direction,but at different speeds •the pressure building up as the plates stick andthe sudden release causing the jerking movement which is theearthquake. •An example may be used – likely to be San Andreas Fault. |
