Unit 2 Revision PowerPoint

1. Unit 2 Revision PowerPoint

2. TROPICAL STORMS

3. What are tropical storms? There are four types of tropical storms: • Hurricanes • Willy willies • Typhoons • Cyclones These are the different terms used, but they all mean the same!!

4. What is a tropical storm? • Tropical storms are large areas of low pressure or extreme depressions • Depressions bring very wet and windy conditions. Depressions occur all throughout the year, but are most common around Autumn into Winter. Depressions also bring lots of clouds with them (try to remember a Depression as a depressingly wet and windy day!!!) • The opposite to a Depression is an Anti-Cyclone. Anti-cyclones bring calm weather with clear skies. You can also experience an anti-cyclone all throughout the year. During the summer months, anti-cyclones bring very hot weather with very little cloud and no rain, during the winter you usually get clear skies at night which makes it very cold. Usually in winter you will get lots of frost and fog in the morning as the night brought clear skies. Brrrrrrrr!!! Anti-Cyclones are also referred to as areas of High Pressure. • On satellite images they are shown up as, swirling masses of cloud, with the eye clearly visible at the centre • The eye of the storm is where you will find the calm and clear area at the centre of the tropical storm. • THINK: Why do you think that the eye of the storm may be considered as being dangerous to people?

5. What is a hurricane?

6. EXAM TIP The formation of a tropical storm could appear in two types of question; one involving diagrams and the other asking for a more detailed written response. Make sure that you can tackle both tasks effectively.

7. Where can we find tropical storms? Task: Name down four countries that experience tropical storms.

8. Task: 1. Describe what these images show you 2. Using the photos, can you identify the primary and secondary effects? The island of Haiti was greatly affected by Hurricane Hanna Images of Haiti, an between the Caribbean Sea and the Atlantic Ocean

9. What is a Storm Surge? Storm surges: Abnormal rise of the sea along a shore as the result of a storm; sometimes called a tidal surge http://www.nhc.noaa.gov/HAW2/english/storm_surge.shtml

10. A storm surge is... Storm surge is simply water that is pushed toward the shore by the force of the winds swirling around the storm. This advancing surge combines with the normal tides to create the hurricane storm tide. This rise in water level can cause severe flooding in coastal areas, particularly when the storm tide coincides with the normal high tides. The level of surge in a particular area is also determined by the slope of the continental shelf. A shallow slope off the coast (right, top picture) will allow a greater surge to inundate coastal communities. Communities with a steeper continental shelf (right, bottom picture) will not see as much surge inundation, although large breaking waves can still present major problems. Storm tides, waves, and currents in confined harbours severely damage ships, marinas, and pleasure boats.

11. Reducing the damage from tropical storms In order to reduce the damage from tropical storms, people are advised to follow these three steps: Forecast Prepare Act

12. Forecasting and Preparing for Tropical Storms Did you know?!?! Forecasters analyse large amounts of weather data and use complex computer modelling, but still only have a 20-25% chance of knowing exactly where a tropical storm will strike 48 hours in advance. Two large agencies monitor the movement of tropical storms, one is the ‘National Hurricane Centre’ (Atlantic) and the other is the ‘Joint Typhoon Warning Centre’ (Pacific). Warnings are issued to places where a tropical storm is likely to strike, but it is difficult to predict their movement with complete accuracy. WHY?

13. Tropical Cyclone Aila

14. What happened? Tropical Cyclone Aila hits Bangladesh and India on Monday 25th May 2009 (LEDCs) The tropical cyclone formed in the North Indian Ocean basin which includes the Bay of Bengal and the Arabian Sea For a tropical storm to form it needs the sea surface temperature to exceed 27 degree centigrade and this is common throughout the year in some regions of the Bay of Bengal Tropical Cyclone Season: The first tropical cyclone season peaks in April and May and the second in late October-early November and are caused by areas of low pressure

15. Effects of the Aila Tropical Cyclone Tropical cyclone Storms are the more dangerous and harmful in Bangladesh, They kill many people and livestock and destroy houses and crops as they push inland with force. The effects of the storm surge are greatest when the storm hits at the time of high tide. Aila has left 27 dead and over 400,000 affected in West Bengal so far.

16. NGO schemes in Bangladesh Most people in less developed countries, such as Bangladesh, are unable to afford the same protection as those in richer countries like the USA. With the help of Non-Government Organisations (NGOs), simple yet effective measures are being put in place to protect people from the cyclones that strike the country.

17. Wildfires Warm Up

18. What & Where are they? • Wildfires are a major hazard. • Can spread quickly & burn for a long time! • Dead plants mean that the fires will spread quickly. • Santa Ana Winds – drive the Californian wildfires. • Physical geography (shape) also affects the spread. • South facing slopes mean that the sun dries vegetation. • Steep slopes encourage the fire. CASESTUDY : California – Mainly physical Causes CASESTUDY: Greece – Mainly Human Causes

19. CAUSES Natural Human Accidents – to blame for starting many wildfires. Matches, Campfires, Cigarettes. Broken bottles magnify the sunlight. Slash & burn, can get out of control. Arson is when people set fires deliberately. Others include sparks from train wheels or machinery, military, BBQs & Chimneys. • Lightning – Biggest single cause of wildfires. • Need the right conditions to develop as smaller strikes die out quicker. • Spontaneous Heating - is the warming up of material until it catches fire without a spark being present. • Need large amounts of dead dry plant. • Volcanic eruptions - with red hot lava and ash. • Hot & Dry conditions.

20. EFFECTS Primary Secondary Loss of Jobs & Income Farm Workers & Businesses Homelessness Rebuilding of Properties takes a long time Insurance increase Damage to Economy Tourism disrupted Restricted access to recreational areas Increase risk of soil erosion & landslides Increased surface run-off Loss of habitats • Loss of Life • Injury • Destruction of Property & Possessions • Burning of Vegetation & Crops • Water & Air Pollution • Health Problems • Breathing Difficulties

21. Responses • Fire-Fighting teams spray them with water & foam. • Aeroplanes & Helicopters can access the area • AIR DROPS • Water & Fire-Retardant chemicals • Large Buckets attached to planes • Fire lines/fire breaks, act as a barrier • Dig trenches or clear areas of ground • Remove dry grasses, bushes, leaves, twigs, which act as fuel for the fire • Pulaski – cross between a hoe & an axe • Backfire – controlled burning in the path of the fire.

22. Preventing & Preparing • Volunteer groups – remove leaves • Controlled burning • EDUCATION! Enhances public awareness • The Smokey Bear campaign • Advice on burning debris • Reducing the risk of sparks • Posters, leaflets, advertisements, • DVD’s sent to schools • Evacuation plans • GIS technologies

23. Prediction (more to come) • Changes to wildfire intensity (severity of burning) • Increase in areas experiencing them • Increase in wildfire season • High amount of wildfires coincide with above-average temperature and early snowmelt • Some scientists believe that climate change, due to global warming, mean that wildfires will continue to increase • They also believe that areas that don’t currently experience wildfires will do soon • In areas where they are common they will burn for longer, and be more intense • These will release stored CO2 into the atmosphere, further contributing to global warming.

24. Other Beliefs • Some believe that periods of increased wildfires are part of a natural cycle • Higher temperatures & lower rainfall • Detailed studies of wildfires across the globe to see if changes are permanent • Cost of damage is increasing • Especially in MEDCs

25. The crust is solid and varies in size between about 6 to 64km (4 to 40 miles) thick The mantle is semi liquid at the top solid near the bottom. And is 2,900km (1,800 miles) thick The outer core is a liquid, 2,000 km (1,240 miles) thick The inner core is a solid, 2,740km (1,700 miles) thick INSIDE THE EARTH • There are four main layers of Earth • The inner core is a solid. It is five times more dense than surface rocks. • The outer core is a liquid. • The mantle is a semi liquid, containing low-density material, and is about 2,900 km thick. • The crust is a solid and is divided into two main types: oceanic crust and continental crust. • The crust • The depth of the crust varies between 6 km and 64 km.  • Continental crust is mostly formed of granite. • Continental crust is less dense than the oceanic crust. • Because it is denser the oceanic crust plunges beneath the continental one when they come together. Task: Draw an annotated diagram of a cross section through the earth.

26. Continental Drift As early as 1620 Francis Bacon noted the jigsaw-like ‘fit’ of the continents In 1912 Wegener put forward the theory of continental drift He proposed that a ‘super continent’ called Pangea split into Gondwanaland and Laurasia, separated by the Tethys Sea Source; USGS What was his evidence? Geology– Geological correspondence between continents, e.g. the Appalachian Mountains of the USA and the mountains of NW Europe Climatology- Evidence of glaciation in Brazil and India. Coal, sandstone and limestone would not have formed in Britain’s present climate Biology- Evidence of same fossils from each side of Atlantic Ocean, e.g. Mesosaurus fossils found only in Brazil and South Africa

27. Plate movement What makes plates move? Powerful convection currents generated from the heat of the Earth’s centre, move the plates above Oceanic crust is heavier and is being destroyed in some places (subduction). In others it is being formed (e.g. Mid-Atlantic Ridge) The Eurasian plate is a mixture of both types This is where plate movement causes earthquakes and / or volcanoes and landforms associated with the particular type of boundary They’re either pushed up, subducted or new crust forms between them

28. What is continental drift?

29. 7 5 5 5 7 3 5 4 1 2 1 3 3 2 2 2 2 5 3 10 18 17 18 6 key Plates Rate of movement (cm per year) D Juan de Fuca A Adriatic Earthquake foci Collision zone Constructive margin E Cocos B Aegean Movement of plates C Turkish Destructive zones Uncertain plate boundary Complete worksheet and stick in your books. THE WORLD’S MAIN PLATE BOUNDARIES

30. Divergent margin Convergent margin (subduction) Plate 1 Plate 2 Plate 1 Plate 2 Continental crust Oceanic trench Oceanic crust Oceanic crust Mid-ocean ridge Rift valley Lithosphere Lithosphere Asthenosphere Asthenosphere TYPES OF PLATE BOUNDARYTask: Using these slides and page 64 and page 65 of the text book draw annotated diagrams of each plate boundary. 2 Destructive margin (subduction zone) Processes • The oceanic crust moves towards the continental crust and sinks beneath it due to its greater density. • Deep sea trenches and island arcs are formed. • Volcanic activity is common. • Example: Nazca sinks under the South American plate. 1 Constructive margins (spreading or divergent plates) Processes • Two plates move apart from each other. • New oceanic crust is formed, creating mid ocean ridges. • Volcanic activity is common. • Mid Atlantic Ridge (Europe is moving away from North America).

31. Iceland Iceland lies on the plate boundary between the North American and the Eurasian plates. The Island has been created by the divergent plate movement. The photo shows Thingvellir – to the right is the Eurasian plate, and to the left is the North American plate Plates pulling apart

32. Convergent margin (collision) Transform fault margin Plate 1 Plate 2 Plate 1 Plate 2 Continental crust Transform fault Continental crust Lithosphere Lithosphere Asthenosphere Asthenosphere TYPES OF PLATE BOUNDARY (CONTINUED) 3 Collision zones Processes • Two continental crusts collide. • As neither can sink they are folded up into fold mountains. • Example: The Indian plate collided with the Eurasian plate to form the Himalayas. 4 Conservative margins (passive margins or transform plates) Processes • Two plates move sideways past each other but land is neither destroyed nor created. • Example: San Andreas fault in California.

33. The San Andreas Fault Runs 1300km through California The last great earthquake to hit San Francisco was in 1906….

34. Tectonic hazards: earthquakes An earthquake is the shaking of the ground due to a sudden release of energy. What causes this to happen? It occurs because there is a fracture (break) or sudden movement in the Earth’s crust. This usually happens because the plates that make up the Earth’s crust are moving. Seismic waves spread out from the focus The further the waves travel the more energy they lose and the less damage they are likely to do The focus is the place where the fracture or break in actually happens inside the crust The epicentre is the place on the surface, directly above the focus, where the earthquake waves are first felt

35. Varying impacts • Why does the damage from an earthquake vary substantially • from one location to another? • The extent of earthquake damage is influenced by: • Magnitude • The time of the day it strikes • The structural materials of the buildings • The duration of the earthquake • The depth of the focus and distance from epicentre • The nature of the underlying material (rock or unconsolidated sediment) • The population (total and density) of the area • The level of economic development / disaster response • The vulnerability of the population • Secondary hazards such as fires, landslides and tsunami. • The occurrence of aftershocks • Other factors may hinder rescue and response efforts, e.g. conflicts, terrain, weather • Human alterations to the natural environment

36. How does where you live affect the impact of an Earthquake? Likely to be high, thousands Probably fairly low Lower number due to good rescue services and education of people Many, lots from aftershocks and people trying to rescue others Extensive, especially to buildings Structures more likely to be ‘earthquake proof’ Potentially a long term problem. Quite low as people are more likely to be insured, so be able to rebuild Not too high, but more of a problem in an LEDC. More likely to need aid Very high due to greater amount of possessions, and insurance claims

37. Measuring the magnitude of earthquakes Each level goes up by a magnitude of 10.

38. Kobe Earthquake, Japan,1995, MEDC Tuesday January 17th at 5.46am, measuring 7.3 on the Richter scale. The epicenter was on Awaji Island just across from Kobe. The focus was 14 km deep. There is a fault running through the Kobe area, which had not moved for 50 years, so a lot of pressure had built up. Nearly 6,500 people lost their lives; 4,600 of these were from Kobe – the closest city to the epicentre. 300,000 people lost their homes. $200 billion damage – 2.5% of Japan’s GDP at the time Within 5 weeks there had been 50 aftershocks. There were 1350 After shocks in total Fires caused by ruptured gas lines caused secondary damage. Water mains burst and roads were blocked. 130km of bullet train track was closed. 12 trains were derailed. Most collapsed structures did adhere to building codes, but only to out-dated 1960’s standards 1 in 5 of the buildings in the worst affected area of the city collapsed. Buildings collapsed or were damaged. 85% of schools were destroyed, 12% of industry was lost and 90% of the port. The soil liquefied and many building sank at strange angles. Army led relief effort. Vital supplies flown in, e.g. tents medical supplies, food, water and rescue teams. Government criticized for not doing enough to help. Army took to long to arrive. They also turned down help from other countries.

39. COPING WITH EARTHQUAKES People cope with hazards in a number of ways. • At an individual level three important factors affect how a person copes: • Experience: people with more experience of hazards are better able to adjust to them. • Levels of wealth: people with more money have more choices open to them. • Personality: is the person a leader or a follower, a risk-taker or very cautious? The three basic options from which they can choose are: • to do nothing and accept the hazard. • to adjust to living in a hazardous environment. • to leave the area. The first and last options are the most extreme actions. In most cases, the middle option is used. How people adjust to the hazard depends on: • the type of hazard. • the risk (probability) of the hazard - several factors influence how people view the risk. • the likely cost (loss) caused by the hazard. Ways of managing the consequences of a hazard include: • sharing the cost of loss, through insurance or disaster relief. • modifying the hazard event, through building design, building location and emergency procedures. • improved forecasting and warning.

41. Volcanoes Warm Up

42. Destructive margin (subduction) Plate 2 Plate 1 Oceanic trench Continental crust Oceanic crust Lithosphere Asthenosphere • The plate boundary which causes the most volcanoes. • Processes • The oceanic crust moves towards the continental crust and sinks beneath it due to its greater density. • Deep sea trenches and island arcs are formed. • Volcanic activity is common. • Example: Nazca sinks under the South American plate.

43. 3 TYPES OF VOLCANO

45. Inside the Volcano • The magma chamberis a collection of magma inside the Earth, below the volcano. • The main ventis the main outlet for the magma to escape. • Secondary ventsare smaller outlets through which magma escapes. • The crateris created after an eruption blows the top off the volcano. • An eruption occurs when pressure in the magma chamber forces magma up the main vent, towards the crater at the top of the volcano. Some magma will also be forced out of the secondary vent at the side of the volcano.

46. Causes • Volcanoes form when magma reaches the Earth's surface, causing eruptions of lava and ash. They occur at destructive and constructiveplate boundaries • The immediate effects of volcanic eruptions can be devastating, but they may be beneficial in the long term

47. How They Form • Magma rises through cracks or weaknesses in the Earth's crust. • Pressure builds up inside the Earth. • When this pressure is released, eg as a result of plate movement, magma explodes to the surface causing a volcanic eruption. • The lava from the eruption cools to form new crust. • Over time, after several eruptions, the rock builds up and a volcano forms

48. EFFECTS Primary Secondary Mudflows Changes in landscape/climate Food/water supply Homelessness Businesses Close Insurance Claims Unemployment Premiums increase Tourism depleted • Destroyed by fire • Explosions • Weight of ash • Crops/Livestock destroyed

50. Why Live Near A Volcano • Geothermal Energy • Tourism • Fertile Soils • Mineral Extraction • Raw Materials • Would you live near a volcano?