Section A: The challenges of natural hazards. 1. Natural Hazards. AQA Geography

Transcription

1 Section A: The challenges of natural hazards 1. Natural Hazards Name AQA Geography

2 Natural Hazards / Tectonic Hazards CHECKLIST Examples of different types of natural hazards. Global distribution of volcanoes and earthquakes The structure of the Earth s interior- including different layers and the characteristics of these layers. The movement of the Earth s tectonic plates and why they move (radioactive decay in the core) ridge push, slab pull, convection currents. The 4 different plate boundaries, the hazards that occur there and why they occur there- Destructive plate boundaries, constructive plate boundaries, conservative plate boundaries and collision zones. The primary and secondary (economic, social, environmental) impacts of the Haiti earthquake The immediate and long-term responses to Haiti earthquake. LIC The primary and secondary (economic, social, environmental) impacts of the Japan Earthquake and Tsunami in The immediate and long-term responses to Japan earthquake and tsunami. HIC Know why people live in tectonically active regions of the world. Factors affecting hazard risk- why people choose to live in at risk areas An understanding of the management strategies and responses to the volcano and earthquake s, including monitoring, prediction, protection and planning - before both and after the hazard Tick when revised

3 Natural Hazards Natural Hazards = a natural event (e.g. earthquake or hurricane) that threatens people or has the potential to cause damage, destruction or death Types of natural hazard: Type of hazard Definition Tectonic Hazard Atmospheric Hazard Geomorphological Hazard Biological Hazard Hazards that involve movement of tectonic plates in the Earth s crust e.g. Volcanoes Hazards that involve weather in the atmosphere e.g. Hurricanes Hazards that occur on the earth s surface e.g. Flooding Hazards that involve living organisms e.g. Forest Fires Deforestation- makes hillsides more unstable so landslides are more likely in earthquakes or from heavy rain. Global warming- increases the number of natural hazards such as hurricanes, floods and droughts. Urbanisation- more people live in cities meaning more people are affected by a natural hazard in the area. Population growth- the number of people on the planet is growing so more people are exposed to natural hazards meaning more death and damage are likely. What factors increase hazard risk? Location- most large cities are on the coast, so people are more exposed to hazards such as hurricanes and tsunamis. The structure of the Earth The Lithosphere the upper layer of the Earth, made up of the crust and very top of the mantle. It is about 100Km thick. Continental crust is thick but low density granite rock, normally 35-70Km thick Oceanic crust is thin but high density Basalt Rock, normally 5-10Km thick. The Asthenosphere the semi-molten rock upper part of the mantle, immediately underneath the lithosphere. The tectonic plates move over it. It is about 180Km thick Mantle- semi liquid layer made up of melted rock (MAGMA). Core Solid and made of iron and nickel. Radioactive Decay of Uranium generates heat, making the core 5500 o C

4 Paper 1 Natural Hazards. Name: Define natural hazards : Exam Zone. Give the meaning of the term tectonic hazard: Types of hazards (write them in the circle): What factors increase hazard risk? Fill the arrow with the reasons. Annotate the structure of the earth

5 Key Term Continental crust Oceanic Crust Lithosphere Definition The thicker but less dense part of the Earth s crust, usually 35-70Km thick. The thinner, denser part of the Earth s crust, usually 5-10Km thick. The rigid outer part of the earth made up of the crust and the top of the mantle Asthenosphere The upper layer of the Earth s mantle that the lithosphere moves over. Crust Mantle Core The solid, outer layer of the Earth. The area beneath the Earth s crust consisting of molten rock, magma. The centre of the earth, made of iron and nickel, where radioactive decay of uranium occurs to generate heat. Why do tectonic plates move? Slab pull occurs as denser oceanic crust subducts (sinks). Due to gravity, the rest of the slab (tectonic plate) is pulled along after the subducting section. Ridge push occurs as magma cools, becomes denser and is pulled down away from the ridge by gravity. At an ocean ridge, magma rises and fills the gap between the plates. Cooler magma sinks to complete the convection current. At the top of the mantle, convection current drag plates sideways due to a build-up of pressure. Hot magma rises due to heat from the core to create convection currents.

6 Paper 1 Page 2 Natural Hazards. Name: Complete the boxes Key Term Definition Continental crust The thinner, denser part of the Earth s crust, usually 5-10Km thick. The rigid outer part of the earth made up of the crust and the top of the mantle Asthenosphere The upper layer of the Earth s mantle that the lithosphere moves over. Crust Mantle The area beneath the Earth s crust consisting of molten rock, magma. Core Why do tectonic plates move? Draw the diagram of ridge push / slab pull / convection currents: Where do earthquake and volcanoes occur? Name the plate margin and type of hazard found at them. Mid Atlantic Ridge: California and Haiti: Pacific Ring of fire Japan:

7 Where do earthquake and volcanoes occur? Some earthquakes and volcanoes occur away from plate boundaries e.g. Volcanoes are found at a volcanic hotspot in Hawaii. Japan sits on a destructive plate boundary- where earthquakes and volcanoes occur. The Mid-Atlantic ridge is a constructive plate boundaryearthquakes and volcanoes. California and Haiti sit on conservative plate boundaries, where only earthquakes occur. Most earthquakes and volcanoes occur on plate boundaries around the Pacific- The Pacific Ring of Fire.

8 Physical Process Found on Destructive Plate Boundaries Earthquakes, Tsunami s, Island Arc s and Composite Cone Volcanoes Destructive Plate Boundaries Fold Mountains Continental Plate on Continental Plate (Fold Mountains also formed on Continental and Oceanic)

9 Destructive Plate Boundary Oceanic vs Continental List the hazards found; Paper 1 Page 3 Natural Hazards. Name: Example of a destructive plate boundary; List the landforms found; Draw a destructive plate boundary. You must label it with; Oceanic crust Composite volcanoes Convection currents Slab pull Subduction zone Lithosphere Continental crust Fold Mountains (continental vs continental crust) Example: Fold mountains are formed when plates move. The movement of the two plates forces rock into a series of. Another name of this plate margin: Volcanoes are found at this type of plate boundary. True or false?

10 Constructive Plate Boundaries Occur when tectonic plates move apart from each other. Most tectonic plates move a few centimetres a year. This may not sound much, but over time whole continents have moved. 1. At constructive plate boundaries, the upper part of the mantle melts and the hot magma rises. 2. As the tectonic plates move apart by ridge push/ slab pull, the magma rises to form solid rock, a new part of the oceanic plate. Earthquakes are shallow focus and non-violent. 3. Magma erupts on to the surface. The lava runny creating shield volcanoes which have wide bases, and shallow sloping sides. E.G. Mid Atlantic Ridge; Eurasian and North American plate. They are moving away from each other about 5cm per year. Landforms: shield volcanoes, rift valley (Thingvellir valley), faults, volcanic islands (Surtsey) Conservative Plate Boundaries Tectonic plates move parallel to each other. The two plates can move side by side, either in the same direction at different speeds or in the opposite direction to one another. 1. Pressure builds as the plates are being pulled along by another plate subducting into the athenosphere. 2. As the plates move past each other they get stuck. 3. Eventually the rock fractures and the pressure is released as an earthquake. 4. There are no volcanoes at conservative plate boundaries, as no gaps or subduction between the plates. E.G. San Andreas fault is 800km long, at the plate margin between North American and Pacific Plate. The plates are sliding past each other in the same NW direction. The North American plates is moving at 6cm/yr. Pacific plate is moving faster 10 cm/yr. California has 1000 s of earthquakes hit a year. In M (magnitude) earthquake hit. (Earthquakes are measured on the Richter scale, a logarithmic scale, each increase by 1.0 is ten times as more powerful).

11 Paper 1 Page 4 Natural Hazards. Name: Constructive plate boundary E.g. List the hazards found; List the landforms found; Draw arrows onto the diagram from the numbered descriptions below. 1. Upper part of the mantel melts and hot magma rise. 2. Tectonic plates move apart by ridge push. 3. Magma erupts onto the surface to form shield volcanoes Conservative plate boundary E.g. List the hazard found; Finish the sentences; 1. Pressure buils as the plates are being 2. As the plates move True or false: There are no volcanoes found at this plate boundary. 3. The rock fractures and the pressure

12 2010 Haiti Earthquake12 th January magnitude quake Haiti is located on a conservative/transform Plate boundary. This is where two plates slide past each other. In this case, the North American plate moves West and the Caribbean plate moves East. The plates move 2cm a year. The plates become stuck due to friction along the plate boundary. Leading to the build up of pressure. Energy is released in the form of an earthquake. Background to Haiti Poorly self built houses often on steep slopes made people more vulnerable to landslides and destruction from the earthquake Poorest country in the Western Hemisphere- 66% of people live on $1 a day / GDP Per captia $731 Due to a rapid urbanisation in the capital city-port au Prince, many of the population have to live in slum conditions Most of the population of Port au Prince are uneducated and work in the informal economy Impacts 230,000 dead 300,000 injured 1,000,000 homeless 250,000 residences and 30,000 commercial buildings had collapsed or were severely damaged Airport and port buildings and infrastructure were destroyed Government buildings destroyed People died of broken limbs Hospitals and communication systems were destroyed Aid stations already in Port-Au-Prince were destroyed Responses Tsunami warnings were issued, but there was no tsunami People were buried in mass graves Aid agencies and the USA Army had to co-ordinate the aid effort as so many government buildings were destroyed, it took 48 hours to start distributing aid People had to live in refugee camps, where diseases such as cholera spread and increased the death toll Aid agencies paid people to work to clear up the rubble as their businesses had been destroyed 1 year after the earthquake many people were still living in tents in refugee camps Local people started searching the rubble for survivors, this was then taken over by aid agencies with heavy lifting equipment Why was it a disaster? Poor country with no earthquake proof buildings Destruction of government buildings meant that there was no central location to co-ordinate relief efforts from Poor country= poor healthcare and few doctors Port and airport were destroyed so getting aid in was challenging People having to live in cramped, un-hygienic refugee camps meant that diseases spread rapidly.

13 Paper 1 Page 5 Natural Hazards. Name: Earthquake case studies Haiti Case Study Japan Type of Plate Boundary Date Magnitude Plate names GDP Social Impact 1 primary 1 secondary Economic impact Environmental impact 1 primary 1 secondary Response 1 immediate 1 long- term Spider diagram: Why were the impacts worse in Haiti?

14 Japanese Earthquake and Tsunami Japan (Developed Country) Date 11 th March 2011 Death toll 16,447 Magnitude 9.0 on the Richter Scale Plate Boundary Destructive Eurasian and Pacific Plate the Pacific Plate is subducting under the Eurasian plate GDP / capita Impacts - The cost of the damage and economic losses has been estimated by the government of Japan at 16.9 trillion (over $217 billion), - Fukushima Nuclear Plant was damaged and radiation poisoning was released into the air and soil, leading to further evacuations; A Level 7 Nuclear Event was declared - The insurance bill is expected to reach around $22 billion; this is despite Japan being the best prepared country in the world - Infrastructure damage triggered fires and hampered relief efforts - Power was lost across a wide area of northern Japan, reduced power levels continued after the earthquake due to damage at nuclear power stations - Due to loss of power, manufacturing operations across Japan had to stop, leading to further economic losses - Rebuilding costs of 145billion (4% of Japan s economy) - 111, 944 buildings were destroyed Responses (management) Well prepared emergency crews lead rapid response- emergency crews were in place within 20 minutes of the earthquake, army personnel and additional emergency crews were in the affected area within 24 hours Gas and electricity supplies can be automatically shut off Earthquake proof design Sea water inland contaminated groundwater Earthquake sensors and warning systems caused many industrial facilities to shut down automatically, including the nuclear power stations What made the impacts worse? What reduced the impacts of the earthquake/ Tsunami? Tsunami walls were not high enough to cope with the 10m high tsunami Freezing temperatures hit survivors as a cold front fell over northern Japan days after the quake. The earthquake was high magnitude earthquakes of this size are estimated to happen once every 300 years on average Tsunami warnings were issued- Experts predict that less than 5% of people would have survived in the worst hit areas had it not been for the tsunami warning system and evacuation training which saved thousands of lives Communities were well equipped and residents well drilled to evacuate to designated buildings on higher ground Evacuation routes for tsunamis were well signed Japan educates people by holding earthquake drills and selling earthquake kits- 1 st September every year is earthquake awareness day Good engineering and strict Government building codes will have saved tens of thousands from the earthquake in Tokyo and other built-up areas

15 Paper 1 Page 6 Natural Hazards. Name: Risk Management Haiti Case Study Japan What protection did the two case studies have in place for the earthquake? Task: For the 3 P s. Add examples around the letter P. Use one colour for volcanoes / one colour for earthquakes. Finish the word off for the started P; Prediction (and monitoring), Protection, Planning.

16 Why do people live at plate boundaries? Risk Management Rich with minerals such as gold, lead, silver and zinc Settlements established near fertile land Pressures of world population force people into potentially risky areas People evaluate the risk of an event happening as worth the risk to be near resources Settlements are well established with friends and family not wanting to relocate People live near the coast for tourism and fishing (tsunami risk) Geothermal energy source Mining sulphur Tourism- 100 million people visit volcanic sites every year Prediction methods Volcano Tiltmeter- measures dome of volcano Gas emissions- high sulphur dioxide before an eruption Spider robots- climb into volcanoes to take measurements GPS satellite- monitors deformation Seismometers- measures tremors Thermal heat sensors- detect temperature changes within volcano Measure temperature- take temperature readings in local streams and rivers Earthquake Radon detectors- detects any radon given off in the area which could be a sign of activity Seismometers- measure tremors Pattern maps- plot previous eruptions on maps to spot danger zones Animals acting strangely- certain animals will act differently before an eruption Protection methods Volcano Evacuation- set up blast radius to keep locals away Lahar channels- set up channels for the lava to run in away from homes Earthquake Shake table- build skyscrapers on a movable table that soaks up the tremors Strengthen roads and bridges- helps emergency services get to sites and prevents collapses Aseismic buildings- earthquake resistant e.g. rubber crumb cement to move with tremors Rubber shock absorbers- soak up tremors preventing tall buildings from toppling Planning methods Volcano Emergency shelter- refugee camps set up with food supplies Exclusion zones- where not to go to stay safe Education- people will know about preventing damage from harmful gases

17 Earthquake Furniture fastened down- less damage if trapped in house Evacuation centres- for those who lose homes Earthquake drills- practised for major events in Japanese curriculum Emergency supplies readied by Red Cross with safety packages Earthquake proof building

18 Paper 1 Page 7 Natural Hazards. Name: Draw and label two earthquake proof buildings. One for a HIC, one for a LIC. HIC LIC

19 Exam Questions: Define tectonic plate (1 mark) What is the asthenosphere? (1 mark) Give the meaning of the term tectonic hazard (2 marks) Describe one way a region affected by earthquakes can prepare for this hazard. (2 marks) How do oceanic and continental crusts differ? (2 marks) Name the landforms found at a constructive plate boundary (2 mark) What forces are at work at a constructive plate boundary? (2 marks) Describe the distribution of areas most risk of tectonic hazards (2 marks) Using an example(s), describe the effects of earthquakes on people and property. (4 marks) Explain how tectonic plates move (4 marks) Explain why both earthquakes and volcanoes can occur on a destructive plate boundary (4 marks) Draw and label a diagram of a constructive plate boundary (4 marks) Give 2 differences between shield and composite volcanoes (4 marks) Explain how volcanoes form at destructive plate boundaries? (4 marks) What were the primary and secondary effects of the Haiti earthquake? (4 marks) Describe two ways in which tectonic hazards can be predicted (4 marks) Compare the impacts of two earthquakes in contrasting locations (6 marks) Evaluate the management strategies used to reduce the impacts of one tectonic hazard you have studied. (6 marks) Suggest reasons why developing countries are more vulnerable to either earthquake OR volcano damage. (6 marks) Explain why some tectonic hazards cause more deaths than others (6 marks) Evaluate the success of management strategies for one tectonic hazard you have studied (9 marks) For a named earthquake event, assess the primary and secondary impacts (9 marks) To what extent would you agree is it easier to manage earthquakes in a HIC rather than a LIC? (9 marks) Discuss. Is prediction, protection or planning the most useful in reducing risks of a tectonic hazard? (9 marks)

20 Suggested Revision Activities: Complete a venn diagram / comparison alley for the impacts/ responses of your two earthquake case studies Test your memory on the structure of the Earth by playing maps from memory against yourself (look at the diagram, cover it and re-draw it from memory) Create a case study facts and figures quiz and ask a willing volunteer to test you on it Create flash cards with exam questions on one side, and the answer on the other Create a plasticine model of the different types of plate boundaries- can you add labels? Make a jigsaw puzzle of the two types of earthquake building designs. General Revision Activities Flash Cards which have the key term on one side and its meaning on the other, used for check and test Revision Quiz As simple as a piece of A4 paper folded into a booklet with at least 10 questions on the outside and answers on the inside. Use the revision checklist to ensure your quiz covers all key contents. Mind Map Use a combination of key words, colours, symbols and pictures/sketches to summarise the key knowledge needed for each case study based on the revision check list Revision Guide Answer all the areas on a revision checklist, presenting it however you like Exam practice KEY WORD GLOSSARY Key Term Crust Lithosphere Asthenosphere Mantle Core Primary Effects/impacts Secondary Effects/ impacts Responses Immediate responses Long-term responses Focus Epicentre Destructive Constructive Rift Valley Richter Scale Conservative Volcanic Hotspot Continental Crust Oceanic Crust Meaning The outer layer of the earth, made of solid rock which is split into tectonic plates The crust and the very top of the mantle, this is a solid layer The semi-molten upper part of the mantle that the earth s tectonic plates rest on A layer of the earth, that is made up of a highly viscous liquid The centre of the earth, the inner part is solid iron and nickel (due to high pressure) the outer part is liquid iron and nickel Caused instantly be a tectonic event e.g. roads destroyed by lava or buildings collapse from shaking in an earthquake In the hours, days and weeks after a tectonic event e.g. people made homeless as buildings are destroyed, food/ water shortages occur Management strategies put in place either before or after a tectonic event to minimize the impacts Happen immediately e.g. provide shelter, food and water. Happen after a period of time e.g. schools rebuilt, remembrance days, improved building regulations. The point within the earth s crust where an earthquake starts, this is where the energy creating the shock waves is released from The point on the earth s surface directly above the focus, where an earthquake is strongest A plate boundary where an oceanic and continental plate move towards each other and oceanic crust subducts. High magnitude earthquakes and composite volcanoes occur e.g. Merapi Where two plates move apart, shield volcanoes form islands when they break the ocean s surface e.g. Iceland on the Mid-Atlantic Ridge Formed at constructive plate boundary, a steep sided valley created when land drops as plates move apart. A logarithmic scale that measures the power of earthquakes. One on the scale means the power is increased by 10 not 1. Where two plates slide past each other. No volcanoes form, high magnitude earthquakes occur e.g. the San Andres Fault, California Where volcanoes form in the middle of a plate due to a magma plume in the mantle, where magma rises up and melts the plate above, shield volcanoes are formed e.g. Kilauea, Hawaii, Pacific Ocean Thick, low density crust (6-60Km thick) made of rocks such as granite Thin, high density crust (0-6Km thick) made of rocks such as basalt

21 Convection Currents Basaltic lava Andesitic lava Shield volcano Composite volcano Tsunami Deforestation Urbanisation Slab Pull Ridge Push Atmospheric hazards Geomorphological hazards Biological Hazards Global Warming Caused by heat from radioactive decay in the core, these occur in the mantle and drive the movement of tectonic plates Thin, runny lava (low viscosity) this flows along way before cooling, creating shield volcanoes Thick, gloopy lava (high viscosity) this cools rapidly creating composite volcanoes. Produces highly explosive eruptions Forms with gentle slopes and a wide base e.g. Kilauea, Hawaii from basaltic lava Forms with steep slopes and a narrow base e.g. Merapi, Indonesia from composite lava and ash layers A large wave caused by another tectonic hazard event, usually an under-ocean earthquake Increases hazard risk by removing trees which bind soil together, this increases risk of landslides Increases hazard risk by meaning more people live in one area and there are more impermeable surfaces Happens at destructive plate boundaries, the subduction of oceanic crust due to gravity pulls the rest of the plate along, making it move Happens at constructive plate boundaries, magma rises up to create a ridge, lava cools, solidifies and gravity then pushes this section of crust down away from the plate boundary, causing the rest of the plate to move. Hazards that involve weather in the atmosphere e.g. Hurricanes Hazards that occur on the earth s surface e.g. Flooding Hazards that involve living organisms e.g. Forest Fires The increasing temperature of Earth, which increases the magnitude and frequency of hazards such as hurricanes and floods