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P1 The Earth in the Universe • IP1.8 LO: consider the actions that governments can take to reduce the harmful effects of natural disasters • Name the 3 different types of plate boundary. • What happens at each of them? P1 The Earth in the Universe • IP1.8 Geohazards that might affect us P1 The Earth in the Universe • IP1.8 WHAT IS A GEOHAZARD? P1 The Earth in the Universe • IP1.8 What Earth processes can affect us? Geohazards that might affect us today are: • landslide • flood • the effects of a volcanic eruption • earthquake • tsunami P1 The Earth in the Universe • IP1.8 Landslide Landslides are triggered where: • slopes are steep • rocks are weak or fractured • erosion undermines a slope • water builds up in the ground • earthquakes strike • human activities are poorly planned P1 The Earth in the Universe • IP1.8 Collapse But, even on flat ground: • Foundations on weak rock can subside. • Old mine workings can collapse. • Soluble rocks below ground can dissolve. P1 The Earth in the Universe • IP1.8 Flood Floods occur: • in low-lying areas • after a storm upstream • after many wet days upstream • if snow melts quickly • when rivers overflow • on stormy coasts at high tide • if dams burst P1 The Earth in the Universe • IP1.8 Flood mayhem It’s not just the amount of water in a flood: • There are thick mud and silt deposits. • Sewers overflow. • Large objects are swept away: bridges, houses, embankments, cars. • There is electrical danger. P1 The Earth in the Universe • IP1.8 Eruption afar There are no active volcanoes in the UK, but a major eruption elsewhere may cause: • a volcanic winter – from ash and sulfur dioxide in the atmosphere • drought over great regions • widespread crop failure in summer, bitter cold in winter • the whole Earth cooled • fantastic sunsets P1 The Earth in the Universe • IP1.8 Eruption on your doorstep Catastrophic effects include: • blast: 30 km+ – everything is destroyed • tsunami – a great wave in coastal areas • glowing cloud – a red-hot current of ash – travelling with speeds of 100 km/h+ • lava flow – rarely kills because you can get out of the way • lahar – waterlogged volcanic ash flooding down valleys P1 The Earth in the Universe • IP1.8 Earthquakes in the UK • They are not big enough to make surface waves, so little damage occurs. • We can feel seismic waves. • Recent UK earthquakes: www.quakes.bgs.ac.uk/recent_event s/recent_events.html • Earthquakes are plotted from eyewitness accounts. • If you feel an earthquake, send in your evidence: www.quakes.bgs.ac.uk/questionnair e/EqQuestIntroB.html P1 The Earth in the Universe • IP1.8 Earthquake In a catastrophic earthquake: • The ground rises and falls in waves. • There is total destruction of non-flexible structures. • People are killed by falling buildings – outside is safest. • There is risk from falling glass and fire storms. • There may be a tsunami – a huge wave in coastal areas. • Many die afterwards from disease. • The most recent big earthquake: earthquake.usgs.gov/eqcenter/ recenteqsww/index.php?old=world. html P1 The Earth in the Universe • IP1.8 Tsunami These huge waves produced by volcanic eruptions, earthquakes, or submarine landslides: • can form waves over 40 m high • can reach speeds of 1000 km/h • can travel 10 000 km across oceans, killing thousands in coastal areas • can trick you, because water first draws back from the coast – and then thunders back in P1 The Earth in the Universe • IP1.8 Worry? – Us? • Major eruptions and earthquakes affect only the active zones of the Earth. • They don’t happen in the UK. • But – could a geohazard happen here? • What might its effects be? P1 The Earth in the Universe • IP1.8 • http://www.brainpop.com/science/earthsystem/n aturaldisasters/ • http://www.brainpop.com/science/earthsystem/e arthquakes/ • http://www.brainpop.com/science/earthsystem/ts unami/ P1 The Earth in the Universe • IP1.8 Imagine you are in an earthquake... • Using the worksheet as a guide, write down the effects of the earthquake on you and your family. P1 The Earth in the Universe • IP1.8 How can the government prepare their countries for a disaster such as these? Discuss the methods that we would have to use to protect ourselves. P1 The Earth in the Universe • IP1.8 Bingo Volcano Earthquake Conservative Convergent Divergent Tectonic Pangea Wegener Fossils Igneous Metamorphic Pressure Heat Sedimentary Sediment Erosion Weathering Magma