Presentation on theme: "Year 9 Restless Earth Earthquakes and Plate Tectonics"— Presentation transcript:
1Year 9 Restless Earth Earthquakes and Plate Tectonics Revision PowerPoint
2Revise Earthquakes and restless earth using your exercise books, this PowerPoint and relevant sections of BBC Bitesize and learn on the internet geography websites:
3The Earth is divided into 4 layers CrustMantleOuter (Liquid) coreInner (Solid) CoreMake sure you can describe and label the features of the 4 layers...
4The Earth gets hotter towards the centre! 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.Degrees Celsius. Iron and Nickel Km thick. Solid due to the pressure.Liquid Iron and Nickel 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!
5Layer 1 - The CrustThe top layer of the earth – it’s surface its about 5 to 70 km’s deepIts like an orange!The crust is made up of plates – 12 in totalThe plates sit in a layer called the lithosphereBut they don’t quiet fit together and are always moving aroundThis means that they are rubbing against each other, into each other, over each other or away from each other
6Layer 2 – The MantleThe plates are moved around as they are powered from the MantleThe mantle is about 3000 km’s deepIts 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.
7Layer 3 & 4 – The Core The Core is made up of 2 parts The outer core is 1300 km’s in depth and consists of semi liquid molten metalIt is between 4000 – degreesThe Core is made up of 2 partsThe inner and outer coreThe inner core is 800 km in depth and 6000 degrees celsius.The two parts are cause of the magnetic field
9The red dots are Active volcanoes __ Tectonic Plate boundaries The earth’s crust is divided into platesThe plates “float” on the Mantle. They move. They are dragged along by convection currents in the mantle.Volcanoes and 98% of earthquakes occur along the plate boundariesPlate boundaries are where the different plates meet.The red dots are Active volcanoes__ Tectonic Plate boundaries
10There are 4 types of Plate boundary 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.
13Conservative 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
14Collision Plate Boundary This type of plate boundary creates mountains for example the Himalayas where theIndo-Australian plate is colliding with the Eurasian plate.This causes earthquakes in India and China.From geog1
15How do plate boundaries effect New Zealand Where is New Zealand?How do plate boundaries effect New ZealandNorth IslandNew Zealand
17Why do the plate boundaries cause problems for New Zealand? New Zealand 7 August 2012New Zealand 23 December 2012
18What 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.
19Destructive Plate Boundaries Make sure you can explain how a destructive plate boundary causes earthquakes and volcanos.
20“Shaking of the earth’s crust caused by rock movement”. EarthquakesEarthquakes 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.
21Magnitude Focus Richter Scale Aftershock Seismometer Epicentre Keywords:MagnitudeHow strong an earthquake isThe place deep inside the earth where the rocks are moving and gives wayFocusRichter ScaleThe scale on which the strength of an earthquake is measuredAftershockSmaller earthquakes after the main large earthquake.SeismometerAn instrument used to measure the strength of the earthquake.EpicentreThe point at the surface directly above the focus
23The 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.Windows shatter and breakMajor catastrophe123456789Light fittings sway and ornaments fall off shelves.Buildings damaged, walls crumble, windows break, signs fall off shops
24No. of earthquakes per year Richter scale no.No. of earthquakes per yearTypical effects of this magnitude< 3.4Detected only by seismometers30 000Just about noticeable indoors4 800Most people notice them, windows rattle.1400Everyone notices them, dishes may break, open doors swing.500Slight damage to buildings, plaster cracks, bricks fall.100Much damage to buildings: chimneys fall, houses move on foundations.15Serious damage: bridges twist, walls fracture, buildings may collapse.4Great damage, most buildings collapse.> 8.0One every 5 to 10 yearsTotal damage, surface waves seen, objects thrown in the air.
25Why is California at risk? Why is Kobe in Japan at risk? Watch these video clipsNow look at the maps on the next slide-It’s all to do with the North American plate and Pacific plate moving together at different speeds.
26The San Andreas Fault runs along a conservative plate boundary Look at these two maps…The San Andreas Fault runs along a conservative plate boundaryThe North American plate moves at 3cm 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.The Pacific plate moves at 5cm per year.
27Therefore California is at risk, so what happened in 1994? Watch this video to find out…Think about your radio news scripts.Be ready to describe with evidence what happened.
28MAGNITUDE AND EPICENTER The Northridge, Los Angeles earthquake occurred at 4:30 a.m. local time on January 17, 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 TOLLThe 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 DAMAGEThe 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.
33First reports… http://news.bbc.co.uk/1/hi/8455629.stm Immediate aftermathEyewitness to aftershock, descriptions of damage. Death toll rising, Aid arriving.
3412 Nov 2010 Cholera outbreak- link to infrastructure damaged in earthquake.
35Haiti Earthquake! 1653hrs Tuesday 12 January 2010 Key facts to use in a case study!Haiti Earthquake! 1653hrs Tuesday 12 January 2010Magnitude 7 on the Richter scaleAt least 52 aftershocks within 24 hours.An estimated three million people were affected by the quake230,000 people killed.300,000 injured1,000,000 homeless.250,000 homes destroyed.30,000 business premises destroyed.
36Reducing the Effects of earthquakes Remember your mind maps?PredictPlanActWe 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.
37Can we Predict Earthquakes? In Turkey scientists have been trying…But is it accurate enough?Why can’t we use these methods to save lives in the short term?
38Plan: Can we protect our transport links and buildings? 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?
40Reducing 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.
41Reducing the effects of earthquakes Bridges, power stations, medical facilities, building regulations, emergency kits, practice drills, warning systems, earthquake advice centresTiltmeters, falling water levels, radon gas, foreshocks and animal behaviour.PLANPREDICTIONReducing the effects of earthquakesActShort-termLong-termBuilding Regulations, Checking bridges, Educating the populations about what to do, Emergency kits and Personal planning.