Transcript 1.5b
Part 1 Opportunities and risks─Is it rational to live in hazard-prone areas? 1.5 © Ord University Press 2009 How do plate movements create hazards? Part B Quit Part 1 Opportunities and risks─Is it rational to live in hazard-prone areas? Earthquakes What destruction do tectonic hazards cause? Volcanic eruptions Tsunamis © Ord University Press 2009 Quit Part 1 © Ord University Press 2009 Opportunities and risks─Is it rational to live in hazard-prone areas? Quit Part 1 Opportunities and risks─Is it rational to live in hazard-prone areas? What destruction do earthquakes cause? The nearer to the How the does an epicentre, higher earthquake the intensity of the happen? earthquake Seismic wave The point on the crustal surface directly above the focus Earth’s crust Rock first breaks and displaces here. Energy is released © Ord University Press 2009 Epicentre The release of stored energy produces seismic waves Seismic wave Focus Quit Part 1 Opportunities and risks─Is it rational to live in hazard-prone areas? What destruction do earthquakes cause? We can describe earthquakes according to ... How can we The depth of the focus describe earthquakes? Depth of focus Type 0 – 70 km _____________ earthquakes Shallow underground 70 – 300 km _____________ Intermediate earthquakes underground _____________ earthquakes Deep Over 300 km underground The deeper the focus, the ( less / more ) energy the seismic wave has when reaching the earth’s surface. © Ord University Press 2009 Quit Part 1 Opportunities and risks─Is it rational to live in hazard-prone areas? What destruction do earthquakes cause? We can describe earthquakes according to ... The magnitude of the earthquake A seismograph is used to measure the amount of energy released by an earthquake. The _____________indicates this energy. It ranges Richter scale from 1 to 9. © Ord University Press 2009 Quit Part 1 Opportunities and risks─Is it rational to live in hazard-prone areas? What destruction do earthquakes cause? Earthquakes can be described according to ... The intensity of the earthquake The_____________________ Modified Mercalli scale indicates the intensity of an earthquake. According to the degree of damage the earthquake caused, the scale ranges from I to XII. Modified Mercalli scale I © Ord University Press 2009 V VIII XII Quit Part 1 Opportunities and risks─Is it rational to live in hazard-prone areas? What destruction do earthquakes cause? Can you describe the destructive effects of earthquakes? Effects of the 1999 Turkey earthquake Effects of the 2008 Sichuan earthquake (Credit: Altitude/Peter Arnold, Inc.) (Credit: Reuters/OTHK) © Ord University Press 2009 Quit Part 1 Opportunities and risks─Is it rational to live in hazard-prone areas? What destruction do earthquakes cause? Can you describe thephotos destructive More online showing destruction of California earthquake, USA (1989) effects the of earthquakes? Please click Effects of the 1995 Kobe earthquake in Japan (Credit: Getty Images) © Ord University Press 2009 to browse online Effects of the 2007 Niigata earthquake in Japan (Credit: Reuters/OTHK) Quit Part 1 Opportunities and risks─Is it rational to live in hazard-prone areas? What destruction do earthquakes cause? Aftershocks may cause some weakened structure to collapse, resulting in further loss of life and property Breakdown of communication links and damage to hospitals: Relief work is disrupted Improper burial of dead bodies and lack of clean water: Disease may spread A school collapsed in the 2008 Sichuan earthquake (Credit: Julia Kao) © Ord University Press 2009 Quit Part 1 Opportunities and risks─Is it rational to live in hazard-prone areas? What destruction do volcanic eruptions What cause? What materials Volcanic gases destruction do do volcanoes volcanic eject? eruptions cause? Rock fragments Volcanic gases Lava (Credit: Reuters/OTHK) Volcanic ash (Credit: Natural Science Image Library) © Ord University Press 2009 Quit Part 1 Opportunities and risks─Is it rational to live in hazard-prone areas? What destruction do tsunamis cause? The destruction caused by tsunamis is mainly caused by a huge surge of water. Uprooting trees Drowning people Sweeping heavy objects like ships inland Washing away beaches A footage from National Geographic introducing the formation of and crushing structures along the coast tsunamis and their deadly effects Please click © Ord University Press 2009 to browse online Quit Part 1 Opportunities and risks─Is it rational to live in hazard-prone areas? What destruction do tsunamis cause? Although tsunamis are less common than earthquakes and volcanic eruptions, they can be very destructive. Destruction caused in Thailand during the 2004 South Asian tsunami Lack of awareness is one of the major reasons for the serious destruction. © Ord University Press 2009 Quit Part 1 Opportunities and risks─Is it rational to live in hazard-prone areas? What destruction do tsunamis cause? Case study: The South Asian tsunami, 2004 The region off the west Origin of coast of the northern tsunami Sumatra, Indonesia Earthquake, Cause 9.0 on the of the Richter tsunami scale Destruction caused in Thailand during the 2004 South Asian tsunami © Ord University Press 2009 Number Over 280,000 of deaths Quit Part 1 Opportunities and risks─Is it rational to live in hazard-prone areas? What destruction do tsunamis cause? Case study: The South Asian tsunami, 2004 Did the tsunami only hit Indonesia? © Ord University Press 2009 Quit Part 1 Opportunities and risks─Is it rational to live in hazard-prone areas? What destruction do tsunamis cause? Case study: The South Asian tsunami, 2004 Banda Aceh in Sumatra, Indonesia Before the tsunami (Credit: NASA) After the tsunami (Credit: NASA) Let’s compare the scenes before and after the tsunami. © Ord University Press 2009 Quit Part 1 Opportunities and risks─Is it rational to live in hazard-prone areas? Seismographs © Ord University Press 2009 Quit Part 1 Opportunities and risks─Is it rational to live in hazard-prone areas? What kind of damage is caused by lava? Molten lava burns almost everything in its path. Molten lava destroys crops, vegetation, houses, and communication links. People are killed or injured. Lava burns flow atvegetation the Hawaiialong Volcanoes its path National Park, 1973 Volcanic eruption in Rastelli/Corbis) HawaiiSurvey) (Credit: Vittoriano (Credit: U.S. Geological © Ord University Press 2009 Quit Part 1 Opportunities and risks─Is it rational to live in hazard-prone areas? What kind of damage is caused by volcanic ash? Volcanic ash may mix with rainwater, forming _________. It can bury mudflows a village within hours. Ash in the air makes it difficult for people to breathe. Ash in the air can block sunlight, which lowers visibility and affects traffic. © Ord University Press 2009 Mudflow after the eruption of Mount St. Helens, the USA, 1980 (Credit: U.S. Geological Survey) Quit Part 1 Opportunities and risks─Is it rational to live in hazard-prone areas? What kind of damage is caused by volcanic ash? When large amounts of ash cover farmland, it may result in ______ crop ________. failure Food shortages may result. Crops damaged by the volcanic ash erupted from a volcano in Ecuador (Credit: Guillermo Legaria/epa/Corbis) © Ord University Press 2009 Quit Part 1 Opportunities and risks─Is it rational to live in hazard-prone areas? What kind of damage is caused by volcanic ash? The 1980 eruption of Mount St Helens in the USA also caused the following damage. (Credit: U.S. Geological Survey) More online photos of(Credit: the U.S. Geological Survey) 1980 eruption of Mount St Helens Please click © Ord University Press 2009 to browse online Quit Part 1 Opportunities and risks─Is it rational to live in hazard-prone areas? What kind of damage is caused by gases? Large quantities of volcanic gases may affect people’s health and the environment. Sulphuric gases can poison and kill people. They can result in ______ killing acid ______, rain vegetation over a large area. Eruption of Mount St Helens, the USA, 1980 (Credit: U.S. Geological Survey) © Ord University Press 2009 _______________ Carbon dioxide released into the air may intensify greenhouse effect. Quit