Year 9 Restless Earth Earthquakes and Plate Tectonics Revision PowerPoint Revise Earthquakes and restless earth using your exercise books, this PowerPoint and relevant sections of BBC Bitesize and learn on the internet geography websites: http://www.bbc.co.uk/schools/gcsebitesize/geography/natural_hazards/ http://www.geography.learnontheinternet.co.uk/topics/volcanoes.html http://www.geography.learnontheinternet.co.uk/topics/earthquakes.html http://www.geography.learnontheinternet.co.uk/topics/structureofearth. The Earth is divided into 4 layers • • • • Crust Mantle Outer (Liquid) core Inner (Solid) Core • Make sure you can describe and label the features of the 4 layers... Very thin solid “Skin” that we live on. As thin as 8 km in places. The crust is split into plates that “Float” on the Mantle. 5500-6000 Degrees Celsius. Iron and Nickel. 1260 Km thick. Solid due to the pressure. Liquid Iron and Nickel. 2220 Km thick. Forms about half the earth. Solid nearer the surface, but hot and soft nearer the core. The Earth gets hotter towards the centre! The Earth is densest at the inner core! Layer 1 - The Crust • The top layer of the earth – it’s surface its about 5 to 70 km’s deep • Its like an orange! • The crust is made up of plates – 12 in total • The plates sit in a layer called the lithosphere • But they don’t quiet fit together and are always moving around • This means that they are rubbing against each other, into each other, over each other or away from each other Layer 2 – The Mantle • The plates are moved around as they are powered from the Mantle • The mantle is about 3000 km’s deep • Its consists of semi-molten rock and liquid metal. • The energy produces convection currents because it is over 3000 degrees celsius. • This causes the plates to move. • Its like orange peel in a bowl of moving water. Layer 3 & 4 – The Core • The outer core is 1300 km’s in depth and consists of semi liquid molten metal • It is between 4000 – 5000 degrees • The Core is made up of 2 parts • The inner and outer core • The inner core is 800 km in depth and 6000 degrees celsius. • The two parts are cause of the magnetic field This video clip compares the earth to a peach... • http://www.bbc.co.uk/learningzone/clips/structure-of-the-earth/9117.html The earth’s crust is divided into plates The plates “float” on the Mantle. They move. They are dragged along by convection currents in the mantle. Plate boundaries are where the different plates meet. The red dots are Active volcanoes Volcanoes and 98% of earthquakes occur along the plate boundaries __ Tectonic Plate boundaries There are 4 types of Plate boundary. The names we used for them are: Constructive Destructive Conservative Collision Make sure you can describe and explain each one. Ensure you can explain how they cause earthquakes and volcanoes. Constructive Plate Boundary From geog1 Destructive Plate Boundary From geog1 Conservative Plate Boundary This type of plate boundary occurs in California, USA where the North American and Pacific plates slide past each other. The example there is known as the San Andreas fault. It explains why Los Angeles and San Francisco experience earthquakes. From geog1 Collision Plate Boundary This type of plate boundary creates mountains for example the Himalayas where the Indo-Australian plate is colliding with the Eurasian plate. This causes earthquakes in India and China. From geog1 Where is New Zealand? How do plate boundaries effect New Zealand North Island New Zealand Why do the plate boundaries cause problems for New Zealand? • New Zealand 7 August 2012 • http://www.bbc.co.uk/news/world-asia-19160562 • New Zealand 23 December 2012 • http://www.bbc.co.uk/news/world-asia-16313416 What might be happening in New Zealand The Indo Australian plate is being forced under the South Island of New Zealand. The Pacific Plate is being forced under the North Island. Thesea are destructive Plate boundaries. Destructive Plate Boundaries Make sure you can explain how a destructive plate boundary causes earthquakes and volcanos. Earthquakes Earthquakes are the “Shaking of the earth’s crust caused by rock movement”. You need to be able explain the keywords, explain how earthquakes are measured, explain how earthquakes occur and describe and explain a real earthquake by using a case study. You alos need to be able to explain how we try to reduce the effects of earthquakes. Keywords: • Magnitude How strong an earthquake is • Focus The place deep inside the earth where the rocks are moving and gives way • Richter Scale The scale on which the strength of an earthquake is measured • Aftershock Smaller earthquakes after the main large earthquake. • Seismometer An instrument used to measure the strength of the earthquake. • Epicentre The point at the surface directly above the focus Richter Scale Seismometer The Richter Scale A scale used to record the magnitude of earthquakes. Detected by seismometers, but people there won’t even certain there has been an earthquake. 0 1 2 Windows shatter and break 3 Light fittings sway and ornaments fall off shelves. 4 5 6 Major catastrophe 7 Buildings damaged, walls crumble, windows break, signs fall off shops 8 9 Richter scale no. No. of Typical effects of this magnitude earthquakes per year < 3.4 800 000 Detected only by seismometers 3.5 - 4.2 30 000 Just about noticeable indoors 4.3 - 4.8 4 800 Most people notice them, windows rattle. 4.9 - 5.4 1400 Everyone notices them, dishes may break, open doors swing. 5.5 - 6.1 500 Slight damage to buildings, plaster cracks, bricks fall. 6.2 6.9 100 Much damage to buildings: chimneys fall, houses move on foundations. 7.0 - 7.3 15 Serious damage: bridges twist, walls fracture, buildings may collapse. 7.4 - 7.9 4 Great damage, most buildings collapse. > 8.0 One every 5 to 10 years Total damage, surface waves seen, objects thrown in the air. Why is California at risk? Why is Kobe in Japan at risk? Watch these video clips http://www.bbc.co.uk/learningzone/clips/1989-santa-cruz-california-earthquake/5722.html http://www.bbc.co.uk/learningzone/clips/earthquakes-in-california-and-japan/14078.html Now look at the maps on the next slideIt’s all to do with the North American plate and Pacific plate moving together at different speeds. Look at these two maps… The San Andreas Fault runs along a conservative plate boundary The North American plate moves at 3cm per year. The Pacific plate moves at 5cm per year. It’s as if one of the plates is remaining still. As they slide past each other, they get locked together. Enormous pressure builds up. The rock eventually gives way and the plates lurch forward. The energy released is felt as an earthquake. Therefore California is at risk, so what happened in 1994? Watch this video to find out… http://www.bbc.co.uk/mediaselector/check/player/nol/newsid_6720000/newsid_6722300?redirect=672 2349.stm&news=1&nbwm=1&nbram=1&bbwm=1&bbram=1&asb=1 Think about your radio news scripts. Be ready to describe with evidence what happened. MAGNITUDE AND EPICENTER The Northridge, Los Angeles earthquake occurred at 4:30 a.m. local time on January 17, 1994. Northridge is located about 30 km northwest of Los Angeles. This earthquake had a 6.9 magnitude. The duration was about 10 seconds to 20 seconds. DEATH TOLL The number of fatalities in the Northridge earthquake was 57. About 9000 people were injured. The fact that the earthquake occurred at 4:30 a.m. minimized the death toll. STRUCTURAL DAMAGE The Northridge earthquake caused extensive damage to parking structures and freeway overpasses (Motor way bridges and fly overs) For example, a section of the Antelope Valley Freeway collapsed onto the Golden State Freeway south of Newhall. Also, a section of the Santa Monica Freeway in West Los Angeles collapsed. In addition, a 2500-car parking garage at the California State University at Northridge collapsed. This structure was about 3 km away from the epicenter. Furthermore, the Northridge earthquake triggered landslides in the Santa Susana Mountains, Santa Monica Mountains, and western San Gabriel Mountains. These landslides damaged homes, blocked roads and damaged water lines. Year 9 Earthquakes Haiti 12 January 2010 Where is Haiti? Why is it at risk? First reports… http://news.bbc.co.uk/1/hi/8455629.stm Immediate aftermath http://news.bbc.co.uk/1/hi/world/americas/8458307.stm Eyewitness to aftershock, descriptions of damage. http://news.bbc.co.uk/1/hi/world/americas/8460575.stm Death toll rising, Aid arriving. •http://www.bbc.co.uk/news/world-latin-america-11740647 •12 Nov 2010 Cholera outbreak- link to infrastructure damaged in earthquake. Haiti Earthquake! 1653hrs Tuesday 12 January 2010 • Magnitude 7 on the Richter scale • At least 52 aftershocks within 24 hours. • An estimated three million people were affected by the quake • 230,000 people killed. • 300,000 injured • 1,000,000 homeless. • 250,000 homes destroyed. • 30,000 business premises destroyed. Key facts to use in a case study! Reducing the Effects of earthquakes Remember your mind maps? Predict Plan Act We try to prepare for natural disasters by predicting where and when they might occur, planning for the disaster and taking long and short term actions to help us prepare and cope with them. You will need to use your mind maps about Predict, Plan & Act during our revision lesson and during the homework clubs to recap our discussions, but the next slides will help. Can we Predict Earthquakes? In Turkey scientists have been trying… But is it accurate enough? • http://www.bbc.co.uk/pr ogrammes/p00gmsgt Why can’t we use these methods to save lives in the short term? Plan: Can we protect our transport links and buildings? • http://www.bbc.co.uk/learningzone/clips/engineering-earthquake-resistant-structures/5725.html • What would be required to earthquake proof the infrastructure in an area close to a plate boundary? • Why would this be hard for some LICs? Earthquake proof homes? Reducing the effects of earthquakes ideas. • Earthquake Resistant Buildings - These are built with deep foundations with rubber shock absorbers and concrete reinforced with steel. They are designed to twist and sway, have sprinkler systems and gas cut off valves. These could be expensive and may require high levels of engineering skill to build. • Emergency Plans - These are drawn up, and supplies such as bottled water, medicines, tinned food etc are stockpiled by individuals or the local authorities. LICs and the citizens of poorer countries may not be able to afford to make plans or have stores of food and water to distribute when disaster strikes. • Earthquake Drills - These are held to practise what to do in the event of an earthquake taking place such as the one held in Japan on September 1st every year when the population of Japan practise what to do if an earthquake occurs. Children in California in the USA are taught a “Drop, Cover and Hold on” drill to follow. Practise drills and education cost money that nor all LICs may be able to afford to provide. Bridges, power stations, medical facilities, building regulations, emergency kits, practice drills, warning systems, earthquake advice centres Tiltmeters, falling water levels, radon gas, foreshocks and animal behaviour. Act Reducing the effects of earthquakes Building Regulations, Checking bridges, Educating the populations about what to do, Emergency kits and Personal planning.