Presentation on theme: "Geography Restless Earth GCSE Revision AQA Unit 1 Section A."— Presentation transcript:
1GeographyRestless EarthGCSE RevisionAQA Unit 1 Section A
2Specification PART 1The Earth’s crust is unstable, particularly at plate margins.Distribution of plates; Contrasts between oceanic and continental plates, Destructive, constructive and conservative plate marginsUnique Landforms occur at plate margins.Location and formation of Fold Mountains, Ocean Trenches and Composite and Shield VolcanoesPeople use these landforms as a resource and adapt to the conditions within them.A case study of one range of fold mountains, including the ways in which they are used (Farming, Hydro Electric Power, Mining, Tourism and how people adapt to limited communications, poor soils and steep relief)Volcanoes are hazards resulting from tectonic activity. Their primary and secondary effects are positive as well as negative. Reponses change in the aftermath of the eruption.Characteristics of different volcanoes; A case study of a volcanic eruption – its cause, primary and secondary effects, positive and negative impacts, immediate and long term responses; monitoring and predicting volcanic eruptions
3Specification PART 2Supervolcanoes are on a much bigger scale than other volcanoes and an eruption would have global consequences.The characteristics of a supervolcano and the likely effects of an eruptionEarthquakes occur at constructive, destructive and conservative plate margins.Location and cause of earthquakes; features of earthquakes – epicentre, focus, shockwaves and the measurement of earthquakes using the Richter and Mercalli scalesThe effects of earthquakes and responses to them differ due to contrasts in levels of wealth.A case study of an earthquake in a rich part of the world and one from a poorer area – their specific causes, primary and secondary effects, immediate and long term responses and the need to protect, predict and prepare; contrasts in effects and responses will be clearTsunamis are a specific secondary effect and can have devastating effects in coastal areas.A case study of a tsunami – its cause, effects and responses
4GCSE Case Studies You must include: Background Information (Location, date, time etc.)Cause (Refer to processes, and be specific using technical language and key terms)Effects: Primary and SecondaryImpacts: Positive and Negative, Social, Economic, Environmental and Political (SEEP)Responses: Short Term, Long Term – Use SEEPRemember to be as specific as possible, using actual facts and figures and answering the question
12Divergent / Constructive Plate Boundaries This is where new crust is generated as plates pull away from each other (e.g. Mid-Atlantic Ridge between North American and Eurasian Plates)
13Convergent / Destructive Plate Boundaries This is an example of Subduction where an oceanic (dense) plate collides with a continental (less dense) plate.This means that oceanic crust is destroyed. An example of this is along the West Coast of America.
14Convergent / Destructive Plate Boundaries When two continental crusts meet, mountains are formed (e.g. the Himalayas) – this is NOT destructive.Fold Mountains are formed when rivers deposit sediments on the ocean floor, and as the plates are pushed together, the sediments are forced upwards into fold mountains.
15Transform / Conservative Plate Boundaries Plates slide past each other and crust is not produced or destroyed (e.g. North American plate and Pacific plate)
16Plate Boundary ZonesLess defined boundaries where the effects of plate interaction are unclearExample: African Plate
17Fold Mountains and Ocean Trenches - Locations These are mainly at convergent (destructive) plate boundaries.
18Hot SpotsHot Spots are sections of the Earth’s crust where plumes of magma rise, weakening the crust.AWAY FROM PLATE BOUNDARIES
19Types of Plates Oceanic Plates Continental Plates Newer – most less than 200 million years oldOlder – Most over 1500 million years oldDenserLess denseCan sinkCannot sinkCan be renewed or destroyedCannot be renewed or destroyed
20Case Study – The AndesLongest continental mountain range in the world (Area – 3.3 million sq. km)Aconcagua – Largest point in the Andes at 6,962m elevation
21Case Study – The AndesThe Andes cover the Entire Western coast of South America. From North to South, the countries covered are Venezuela down to Argentina (see map). The Andes are not a single line of peaks, they’re actually a succession of parallel and transverse ranges.
22Case Study – The AndesThere are three sections of the Andes, each separated by intermediate depressions. They are a set of fold mountains, formed by the Nazca and South American plates.
23How do people use The Andes? AgricultureHEP (Hydro Electric Power)MiningTourism
24Agriculture in the Andes For over 6,000 years, crops have been irrigated with spring water.Terracing has been installed to combat the steep slopes.Previously, maize and potatoes were the most important crops.
25Agriculture in the Andes Nowadays, tobacco, cotton and coffee are the main export crops.Another important crop is coca is used for herbal tea and also illegally used for the production of cocaine.
26HEP in the AndesHydro Electric Power is easy to collect in the Andes because of their steep slopes and narrow valleys, with its fast running water.174 dams for HEP are found in the Andes, and the elevation is perfect for the production of HEP.
27Mining in the AndesMining is popular because there are large deposits of certain ores and salts, as well as some hydrocarbons.There are huge copper deposits.There are also large potassium nitrate (saltpeter) , lithium and silver deposits.
28Tourism in the AndesActivities in the Andes include Trekking, Mountaineering, Rafting Trips and much more.The most famous trail is the Inca Trail.Tourism is controversial – some claim that traditional life is lost by tourism.
29Tourism in the AndesSustainability issues with Tourism include interrupted wildlife patterns, human buildings, erosion, roads, litter and use of helicopters.
30Key Terminology Commercial Farming – For a profit Subsistence Farming – For survival
31Types of Volcano Composite Volcanoes Shield Volcanoes Destructive plate marginsConstructive plate marginsEruptions infrequent, but violentEruptions frequent, but non-violentNarrow base and steep slopesWide base and gentle slopesHave secondary conesLow, rounded peakContains thick layers of lava and ashLayers of runny lava with little ashMostly lava, oozes out
32Types of VolcanoComposite Shield There is a greater build up in pressure in Composite volcanoes
33Case Study – Montserrat Volcano Background Information Located in Caribbean Sea near the Equator in a tropical location.On the Caribbean next to Atlantic plates.Population of 12,000 before the eruptions occurred.
34Case Study – Montserrat Volcano Background Information Dense tropical forest.104 square kilometres.£2800 – GNP per Capita (LEDC).Overseas Territory of Britain.Once called the Emerald Island.
35Case Study – Montserrat Volcano Background Information The volcano itself is located in the South of the Island and called Mount Soufriere.The eruptions lasted fromComposite Volcano that was peaceful before the eruptions.
36Case Study – Montserrat Volcano Causes Originally a surprise, before lasting for 2 years (first eruption for 350 years).Subduction zone at destructive plate margin – composite volcano.Caribbean and Atlantic Plates.
37Case Study – Montserrat Volcano Causes 1997 saw the worst volcanic activity.The lava flow was 600 oC, going at 20 km/h.The pyroclastic flows (fire with ash and mud) reached up to 130 km/h.
38Case Study – Montserrat Volcano Primary (Immediate) effects 19 people died.The capital – Plymouth – was evacuated.Residents had to choose between leaving or staying put.
39Case Study – Montserrat Volcano Secondary (later) effects Exclusion zone created (Southern part of the island).People forced to move.3500 people left the island.
40Case Study – Montserrat Volcano Secondary (later) effects
41Case Study – Montserrat Volcano Wider Impacts: Positive Encouraged people to go abroad (such as the UK).New start – Capital moved to Little Bay in the North of the island.Land more fertile.5000 people left in total.
42Case Study – Montserrat Volcano Wider Impacts: Negative Economy devastated – no tourists.Half of the island is now uninhabitable.The new airport can only handle 20 seater planes.Main towns, communications and services destroyed.
43Case Study – Montserrat Volcano Responses: Immediate Aid from London.Temporary schools made.Capital evacuated.Emergency food handed out.Southern area became exclusion zone.
44Case Study – Montserrat Volcano Responses: Long Term Rioting over lack of British support.£200m support from Britain.New transport links created.Some people returned and tourists started to return to the island, but the population became a lot more aged.
46SupervolcanoesThis means that more than 1,000 cubic kilometres (240 cubic miles) of magma (partially molten rock) erupt. They are not on plate boundaries.When the chamber reaches its maximum capacity, the colossal pressure that has built up causes a super eruption.Magma rises from the mantle to create a boiling reservoir in the Earth’s crust. This chamber increases steadily in size.Ash can reach up to 30 or 40ft, and there is a 100 mile radius danger zone – this is the reach of a pyroclastic flow.The term “Supervolcano” implies an eruption of magnitude 8 on the VEI Index (Volcano Explosivity Index).
47Key TerminologyCaldera – Crater of a supervolcano (34 by 45 miles at Yellowstone)Fissures – Cracks in the groundGeysers – Ground water heated upGeothermal – Heat under the ground that heats the ground water
48Main Supervolcanoes Toba, Indonesia Taupo, New Zealand (North Island) Long Valley, California, USALongridge, Oregon, USAYellowstone National Park, Wyoming, USA
49More on Supervolcanoes Supervolcanoes are normally above hot and subducted zones.
50Yellowstone Supervolcano 3 known supereruptions at Yellowstone.All of these have been on a 600,000 to 700,000 year cycle, starting 2.1 million years ago.
51Yellowstone Supervolcano The last eruption was 640,000 years ago.On a geological timescale, this suggests that Yellowstone is overdue for an eruption.
52Impacts of a supervolcanic eruption Local Total DevastationPyroclastic flowsLots of ash and lavaAll in the area killed
53Impacts of a supervolcanic eruption National 100 mile radius hit by pyroclastic flowsAsh would block out the sun for 6 years, devastating food suppliesAir travel effectedAnimal killed by the ash – no protection
54Impacts of a supervolcanic eruption Global Ash would block out the sun for 6 years, devastating food suppliesAir travel effectedEntire change in global climate
55Impacts of a supervolcanic eruption Continued – All areas A magma chamber of 80km by 80km by 40km could result in 2 – 3 cubic kilometres of ash with people trapped from a 300km radius.Inhaling of ash makes you drown in “liquid” concrete.
56Impacts of a supervolcanic eruption Continued – All areas 100 tonnes of pumice, rock etc.Wall Street crash.People fighting to leave the countryNeed for back up generators.Traffic chaos, VEI 8, Everything closed, planes destroyed and multiple vents.
57Pyroclastic FlowsCan reach 800 km/h at 500 degrees Celsius.
58EarthquakesEarthquakes can be defined as a shaking movement of the Earth’s crust.They can occur at any plate margin.In theory, earthquakes can occur at any place along the Earth’s crust, but 90% are found at plate boundaries.
59Earthquakes Plates move because of a build up in pressure. The point where the energy is released is called the “focus”.The “epicentre” can be found directly above the focus.
60Earthquakes Shockwaves (tremors) are strongest at the epicentre. There are primary and secondary waves.
62Earthquake ScalesRichter Scale – A scale that uses a seismograph to calculate the strength of earthquakes – its logarithmic nature means that each level is 10x more damaging than the one before – it’s scientific, accurate, easy to understand but not that accessible.
63Earthquake ScalesMercalli Scale – A scale (from I to XII) that uses the damage caused to calculate the scale of the earthquake – it is incredibly quick and easy to evaluate but is a bit vague and could vary between LEDCs and MEDCs.
66Case Study – L’Aquilia Earthquake Key Figures 6th April 2009 – 3.32am (Local Time)2km North North West (NNW) of Aquilia6.3 on the Richter ScaleOver 300 dead (out of about 70,000)Quite an ancient town – liable to destructions
67Case Study – L’Aquilia Earthquake Short Term Impacts About 300 deaths (many more injured)Bridge and water pipe destroyedPeople in bedPrime Minister cancelled Moscow tripThousands of buildings damaged, including earthquake-resistant ones and historic buildings
68Case Study – L’Aquilia Earthquake Short Term Responses Area declared an emergency zone30 million euros national fundingCamps for the homelessRescue operationAll council tax and bills temporarily suspended, free phones given out
69Case Study – L’Aquilia Earthquake Short Term Responses Toll roads became freeSleeping in railway carriages permitted for the homelessCharity operations begun
70Case Study – L’Aquilia Earthquake Long Term Impacts Fires caused more damageAftershocks hampered rescue effortsLandslide
71Case Study – L’Aquilia Earthquake Long Term Responses New town built, though Italy originally refused international aidInvestigation on building safety20,000 of the 70,000 that once lived in L’Aquilia were unable to return even 5 years onEarthquake scientists given 6 year prison sentence for manslaughter
73Case Study – Sichuan Earthquake Key Figures 12th May 2008 – 2.28pm (Local Time)Lasted for 120 seconds7.9 on the Richter Scale69,000 people known to have diedEstimated cost totalled $75 million
74Case Study – Sichuan Earthquake Short Term Impacts About 69,000 people died5 million buildings collapsed, including chemical plants that spilled toxic ammoniaRoads and rivers blocked
75Case Study – Sichuan Earthquake Short Term Responses 20 helicopters assigned to rescue efforts immediately after the disasterTroops parachutedTent, clean water and food supplies given to any survivors
76Case Study – Sichuan Earthquake Long Term Impacts 18,000 people still missing two months after the earthquake5,000,000 homelessPhones cut off (landline and mobile)
77Case Study – Sichuan Earthquake Long Term Responses $75 million needed for rescue effortsHelp from Japan, Russia and South Korea£100 million donation by the Red Cross1 million temporary homes built and a $10 million rebuilding fund set aside
78Earthquake Comparisons L’AquiliaSichuan300 dead69,000 dead30 million euros needed$85 million + £100 million neededCamps and railway carriages provided for the homeless5,000,000 homeless – had to stay elsewherePhones handed outAll phone lines destroyed
79Factors affecting earthquake effects MagnitudeRural / UrbanPopulation sizeBuilding QualityTime of DayMEDC / LEDCSpread of diseaseCommunication linksAvailability of emergency services
80Predicting Earthquakes Parkfield, USA, had a run of earthquakes from the 1800s to the 1960s where a magnitude 6 earthquake hit every 22 years or so. However, the pattern ended when the USGS came to investigate (United States Geological Survey)
81Predicting Earthquakes Fence offsets can show tremorsStress built up can be reviewed by instrumentsGround can rise by up to 6 metresPredicting the size of the earthquake is particularly crucial
82Predicting Earthquakes The Chaos Theory looks at the amount of chaos and mathematical formulas – it has a very high accuracy rateOther mysterious earthquake changes include ground water level, animal behaviour and bright lights in the sky
83Predicting Earthquakes Chinese Snakes – In the case of an earthquake, they will try to escape their enclosure or even kill themselvesBright lights in the sky might be caused by small currents in crushed rocks – there might also be electromagnetic pulses
84Predicting Earthquakes A key question is whether to put money intoPredicting earthquakesMaking the buildings so that they don’t fall down and kill people in the first place
85Predicting Earthquakes Earthquake drills are taughtAt the moment, we have to say no to predictionUSGS – Could they make recording systems along the San Andreas Fault to create an early warning system? – This would cost 100 million dollars, but would save 200 billion dollars
86The Three Ps – Hazard Management At a glance Prediction – Trying to forecast when an event will happen (volcanoes are easier than earthquakes)Protection – Constructing buildings to meet appropriate safety standardsPreparation – Organising drills and codes of practise so that people know what to do in the case of an emergency
87The Three Ps – Hazard Management Key Idea The effects of and responses to volcanic eruptions and earthquakes, and how they differ due to contrasts in levels of wealth.
88Monitoring Techniques Volcano PredictionWarning SignsMonitoring TechniquesHundreds of small earthquakes as magma rises up through cracksSeismometers are used to detect earthquakesTemperatures increase around the volcano as activity increasesThermal imaging techniques and satellite cameras can detect heatWhen near to erupting, gas is released, which increases in levels of sulphur as the eruption nearsGas samples and chemical sensors are used to measure sulphur levels
89Earthquake Prediction Monitoring of water levelsUsing seismometers for ground movementLooking at past patternsStrange animal behaviourRocks with small charge when crushedMonitoring release of radon gasLaser beams across a fault for any small movements
90Earthquake Protection Liquefaction is where sediments sink and water rises when earthquakes occur, making anything above the ground (like a house) unstable. This can be prevented by fitting flexible strings down into stiff ground
91Earthquake Protection The Transamerica Pyramid in San Francisco is designed to combat the force of an earthquake by changing its shape and being fitted with stability supports amongst other features.
93Earthquake Preparation TV / Radio / School Earthquake Drills (using “DROP – COVER – HOLD ON)Roads and Bridges to withstand powerEarthquake-proof buildings like “The Transamerica Pyramid”Emergency kits (first-aid items, blankets, tinned food etc.)
94Suggestions for Preparation Strap heavy objects to wallsEmergency closets – easily accessibleFire extinguishersRoof in a good condition
95Scientist Research Scientists have concentrated on protection This is because prediction has been proven to be too difficult to achieve
96Why do people stay at risk? This is because volcanic land can be more fertile than others, it may be the only space available and some places may have been established before our knowledge of earthquakes and volcanoes had developed
97TsunamisThese are special types of wave caused by water being displaced upwards, generally by an earthquake.They are unlike most other waves, which are caused by the wind.
98Indian Ocean Case Study The epicentre of the earthquake was in the Indian Ocean, near Banda Aceh in Indonesia.220,000 died, 650,000 were injured, 2 million became homeless and people that knew the rescue procedure were killed before they could help.
99Indian Ocean Case Study Most fishing boats were destroyed (primary industry), and the area was isolated due to rail/road links damaged.Trees uprooted, drinking water contaminated and salinisation occurred, making the land infertile.
100GeographyRestless EarthGCSE RevisionAQA Unit 1 Section A