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Earthquakes and volcanoes What are they? 1. energy Seismicwaves wavesreleased when plates move past each other 2. Richter logarithmic scalescale that measures earthquake magnitude 3. Continental thick, granitecrust plates that “float” on the mantle. They are less dense than oceanic plates. 4. Tsunami wave created by an underwater earthquake 5. Tectonic where two boundary tectonic plates meet. 6. Convergent/destructive where two plates meet, oceanic margin plate is subducted below continental to form volcanoes/earthquakes 7. Divergent/constructive where two plates move apart margin creating a chain of volcanoes e.g. Mid ocean trench 8. Evacuate move people away from danger 9. Geothermal energy formed energy by the heat of the earth 10. Pyroclastic material erupted flow from a volcano inc. ash, lava, gas and rocks The following slide shows 4 plate boundaries. For each one i. Name the boundary. ii. Say what hazards it creates. iii. Give an example of where it happens. B A a. collisional b. Mountains and earthquakes c. Himalayas C a. Conservative / tranform b. earthquakes c. California, Northridge a. Constructive / divergent b. volcanoes and (very occ) earthquakes c. Iceland D a. Destructive, collisional b. volcanoes and earthquakes c. Andes, Mount St Helens, Montserrat Minimising the effects a. b. c. d. e. f. Emergency Drills – emergency services know exactly what to do so they are organised [1] and can get people to safety quickly and efficiently leading to less death [1] Measuring gas emissions from vents – as magma rises gases like sulphur are released [1] if emissions are increase it shows an eruption is imminent and so people can be evacuated to safety [1] Placing concrete blocks on the ground – concrete blocks can be placed in the path of lava [1] this diverts the lava away from key buildings or infrastructure [1] reducing damage and speeding up rebuilding Counterweights in buildings – these reduce shaking of tall buildings [1] this leads to less buildings collapsing [1] which reduces the death toll (from falling building material) and cost of damage [1] Monitoring animal behaviour – animals and birds often leave an area in the hours before a quake [1] if animal behaviour is monitored this can give us an early warning sign [1] and can lead to early evacuation [1] Education – If people are aware of danger and how to react to it they can be prepared [1] this means in an emergency they know where to go and how to find out what is happening [1] reducing panic and confusion which can slow rescue [1] Causes of Hazards a. Destructive boundary Caribbean and N and S American Plates. Composite volcano which means its eruptions are sudden and violent b. Divergent boundary N. American Plate and Eurasian. Shield volcano so gentle eruption. Glacier on top of volcano melted forming floods and cooling lava to form ash. c. Conservative boundary – Caribbean and North American Plates Epicentre was 25km from capital so the major city and centre of emergency planning was destroyed. No strict rules of construction so buildings weren’t strong d. Conservative boundary N American and Pacific Plate. 15000 aftershocks which lead to damaged buildings collapsing. Landslides blocked roads Development Compare the likely effects of an earthquake in an MEDC and an LEDC. Explain the likely differences. Preparing for hazards Suggest two ways that people can prepare for or predict a. Earthquakes b. Volcanoes For each one explain how this would be effective