Living with earthquakes and volcanoes


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Living with earthquakes and volcanoes

  1. 1. »1 Living with earthquakes and volcanoes Earthquakes and volcanic eruptions can have disastrous effects, especially if they happen in places where many people live. Understanding the causes and effects of earthquakes and volcanoes can help to reduce their effects on people and environments. Learning objectives What are you going to learn about in this chapter? > Where earthquakes and volcanoes happen > Why earthquakes and volcanic eruptions happen > The effects of earthquakes and volcanoes in different parts of the world > How the effects of earthquakes and volcanoes can be reduced A Earthquake in Kobe, Japan > How a tsunami starts > What it is like to live through a tsunami > Why aid is needed after a natural disaster > Why people live in active areas 5
  2. 2. What is the earth like? > Understanding that the earth is not a solid mass > Finding out that inside the earth it is very hot The earth is made up of three main layers: the crust, the mantle and the core (A). The crust is a thin surface which forms the land on which we live. A The earth’s layers It floats on the semi-liquid (molten) mantle. The core is the centre of the earth and is made of iron. Plates The core Huge blocks of the earth’s crust. Scientists believe that: • the inner core is solid, because it is so dense • the outer core is molten rock. The mantle Plate boundary The mantle is a layer of molten rock Where plates meet. (magma) underneath the crust. The crust • Where land is on the surface it is called continental crust and is usually 20–60 km thick. • Where oceans are on the surface it is called oceanic crust and is thinner – usually between 8 and 25 km thick. • In some places the crust is very thin and molten material bubbles up to the surface through cracks – these are called ‘hot-spots’. Geothermal Power Station Uses Hot Springs, Geysers Water heated up H O W H OT I S hot underground rocks to produce underground rises to the surface under hot water and electricity. enormous pressure. IT INSIDE T H E E A RT H ? No one really knows the answer to this question, but we do know that inside the earth is hotter than the outside. One way we can tell this is when volcanoes erupt or red hot lava comes to the earth’s surface. The photographs in source B show other evidence which tells us that temperatures are higher inside the earth. B Evidence to show that temperatures inside the earth are higher 6 geography 360° Foundation Book 3
  3. 3. Key words T H E E A RT H ’ S C RU S T Continental Plate – plate with land on the surface The earth’s crust is not one solid mass. It is made up of large pieces Lava – molten rock on the called plates (map C). Continental Plates have land on the surface and earth’s surface Oceanic Plates have an ocean on the surface. The plates are slowly Magma – molten rock inside moved around by currents inside the earth. Notice how in some places the earth the plates are moving towards each other and in other places they are Molten – melted moving apart. Plate boundaries are the places where plates meet – this is Oceanic Plate – plate with an where earthquakes and volcanoes often occur. ocean on the surface Plate boundary – where the earth’s plates meet N N or th Eurasian A m er ic an I ra n ian P h ili p p in e Ar P a c i f i c ab ia Caribbean n African Au Ind st o- South ra lia American n Nazca Indo-Australian Key Plate boundary (edge) Earthquakes Antarctic 0 3000 Kilometres Direction in which plate is moving Volcanoes C The earths’s major plates Activities 1 Copy out the following paragraph. Use the words 3 Look at source C. in the box below to fill in the gaps. Start by putting a) Which plate does Britain lie on? the heading: ‘What is the earth like?’ b) Why does Britain not have major earthquakes The earth is made up of ______layers, the crust, and volcanoes? the _______ and the core. The ______ is the part c) Why is the edge of the Pacific Ocean often we live on and is between 8 and 60 km thick. The called ‘the Pacific ring of fire’? mantle is made up of _______rocks called _______. The core is in the _______ of the earth 4 Below are some sentences that describe the and is made of ____________. location of volcanoes. Write out the two that are correct. iron three molten mantle • There are volcanoes along the west coast of magma centre crust South America. 2 How can you tell that it is hot inside the earth? • Britain has lots of active volcanoes. Write a brief paragraph, starting with: ‘There are • The east coast of North America has lots of many ways you can tell that it is hot inside the volcanoes. earth …’ and go on to mention two ways you can • East Africa has a line of volcanoes. tell it is hot inside the earth. 1 Living with earthquakes and volcanoes 7
  4. 4. Why do earthquakes and volcanoes occur in certain places? > Understanding that the earth’s crust is made up of a number of separate pieces called plates > Finding out why earthquakes and volcanoes happen near the edges of the earth’s plates The earth’s crust is made up of a number of huge pieces called plates. These plates are moved by the currents in the hot rocks below the surface. The edges of plates are called margins or boundaries. H O W FA S T D O T H E P L ATE S M OV E ? The plates move between 1 cm and 12 cm a year, which is about the speed of growing fingernails! This does not sound very fast but don’t forget that the earth is millions of years old, so a small movement can make a big difference given enough time. About 160 million years ago South America and Africa were next to each other; today they are separated by the Atlantic Ocean (A). H O W C A N W E TE LL T H AT T H E E A RT H ’ S P L ATE S M OV E ? 2 Rock formations found in South America and Africa are exactly the same, so they Pl must have been formed near each other at e bo un da ry Africa 1 Looking at the shape South America N of South America and Africa, it is clear A t l a n t i c that they fit together O c e a n like a giant jigsaw 3 Identical fossils of land-based prehistoric animals have been found in South America and Movement Africa, so these continents must have been joined 0 4000 Kilometres together 200 million years ago A Plate movement W H AT H A P P E N S W H E R E P L ATE S M E E T ? Plates can move apart, push together or slide past each other. This means that the area where plates meet is very unstable. 8 geography 360° Foundation Book 3
  5. 5. W H AT H A P P E N S W H E N T WO P L ATE S M OV E A PA RT ? 4 The tops of some of the mountains stick up out of the ocean to form islands 3 Mountain ridges form under the sea Iceland ge id R ic nt tla -A A t l a n t i c id M O c e a n E u r o p e N o r t h A m e r i c a 2 The molten rock cools into solid rock 1 Molten rock rises into the gap Plate Molten Plate rock B Plates moving apart W H AT H A P P E N S W H E N A N O C E A N I C P L ATE A N D A CO N T I N E N TA L P L ATE P U S H TO G E T H E R ? 5 Volcanic eruption 4 Liquid rock (magma) rises to the surface Japan Pacific Ocean Eurasian Plate 2 The plates push together, causing earthquakes Pacific Plate 1 The heavier Pacific Plate pushes under the Eurasian Plate 3 Rock begins to melt C Oceanic and continental plates pushing together Activities 1 Copy and complete the following sentences using 3 Write out these statements in the correct order to the words in the box below. show what happens when plates move apart. a) The earth’s crust is made up of a number of • Undersea ridges and mountains are formed ______. • Molten rock rises to the surface and cools b) The plates are moved about by the ________ • Two plates move apart below. 4 Draw a diagram to show what happens when currents plates oceanic and continental plates push together. Mark on: 2 Explain how you can tell that South America and – Volcano – Melting rock Africa haved moved apart. – Rising magma – Start of an earthquake 1 Living with earthquakes and volcanoes 9
  6. 6. What happens in an earthquake? > Finding out why the earth shakes > Learning about how earthquakes are measured Key words Epicentre – the point on the earth’s surface above where Most earthquakes happen when two of the earth’s plates stick as they an earthquake starts push past each other (A). 1 Two plates moving 2 Suddenly the plates move, causing the past each other get plate to jolt apart – sending vibrations jammed together through the crust – an earthquake The point on the surface directly above the focus is called the epicentre Pla te mo vem ent Pla te mo vem ent st Cr u st us t Cr u Cr ntle Ma us t Cr ntle Ma The point underground where the earthquake started is called the focus A How an earthquake can happen W H AT A B O U T T H E S T R E N G T H O F A N E A RT H Q UA K E ? FAC T F I LE The strength of an earthquake is measured by the Richter scale. The The word seismic is Greek for higher the number on the scale the greater the damage. ‘shake’. As earthquakes cause the ground to shake, anything The Richter scale to do with earthquakes is called seismic! Measures the amount of energy released. 1 Only noticed by instruments 2 Barely felt The Richer scale is Each number is ten 3 Slight vibrations calculated using a times more powerful 4 Windows rattle, some movement, minor damage than the last mathematical equation so is very accurate 5 Some damage to buildings 6 Walls crack, some buildings collapse 7 Ground cracks – many buildings collapse 8 Large areas destroyed 8.9 Strongest 9 Widespread destruction recorded earthquake 10 geography 360° Foundation Book 3
  7. 7. H O W A R E E A RT H Q UA K E S M E A S U R E D ? An instrument called Strong earthquake a seismometer is Calm Smaller eathquake used to record the shaking of the earth (photo B). The information collected is shown on a seismograph (C). Comparing seismographs from different places can help to tell where an Time earthquake started. B A seismometer C A seismograph H O W D O E A RT H Q UA K E S C AU S E DA M A G E ? Shaking causes Electrical cables damaged causing fires Buildings destroyed buildings to collapse by the earthquake River banks broken causing flooding Shaking causes landslides Gas pipes broken causing fires Large trees fall causing damage Earth movements cause bridges to collapse Activities 1 What does the word ‘seismic’ mean? 4 Describe three ways in which earthquakes can 2 Draw a diagram like the one on the right. cause damage. Add the words from the box below to explain how an earthquake happens. Crust Mantle Vibrations Plate movement Focus Epicentre 3 Copy out and Type of damage Richter scale complete the table, which describes the Barely felt 2 effects of 4 earthquakes of different strengths. 6 Widespread destruction 9 1 Living with earthquakes and volcanoes 11
  8. 8. Case study: the Kobe earthquake – Japan > Understanding the effects of an earthquake > Finding out how people respond to earthquakes A IA IN SS CH Damage extends to 96 RU Hokkaido kilometres around Kobe including temples in Kyoto N Kobe is the sixth largest city in Japan and one of the N. KOREA world’s largest ports. J A PA N At 5.46 am on 17 January Honshu Kyoto 1995 the city was rocked by S. KOREA Tokyo a massive earthquake (A) Kobe Nearly 12,000 N buildings destroyed recorded at 7.2 on the Osaka Many killed as parts of Richter scale. Epicentre Hanshin Expressway collapse In a matter of minutes one of 0 300 Kilometres the most modern cities in the Nara world had become a disaster Tarumi Kobe area (B, C). At 5.46 am local time tremors International spread from island epicentre Airport unaffected Osaka Bay FAC T F I LE Kobe was Japan’s worst earthquake for 72 years 6,310 people were killed Awaji Island 45,000 people were hurt Wakayama 0 16 Kilometres 75,000 buildings were damaged Rebuilding the city cost over £80 billion A How the earthquake struck B Damaged highway following the Kobe earthquake C Damaged buildings following the Kobe earthquake 12 geography 360° Foundation Book 3
  9. 9. ‘There was a rumbling sound that got louder and louder. Everything started to shake – a lot of buildings began to collapse. Most people did not have W H AT WA S I T L I K E time to get out.’ Local resident TO L I V E T H RO U G H T H E E A RT H Q UA K E ? ‘I was driving to work and the car was suddenly thrown across the road. All These comments were made by the cars stopped. It was only later I was told that the road ahead had people in the area at the time of collapsed, killing a number of people.’ the earthquake. Local factory worker W H AT WA S I T L I K E ‘I was staying in a hotel and was woken up by a flash that lit up the sky. FOR THE I was later told it was an electrical explosion. Everything began to move. EMERGENCY It seemed to last for ages, but was probably only about 20 seconds.’ S E RV I C E S ? Visiting businessman Local fireman Ambulance driver ‘The biggest problem was that fires ‘The biggest problem was getting were breaking out everywhere. to people who needed help. Lots Gas mains and electrical cables were of the roads and bridges were damaged, causing thousands of fires. damaged. Others were blocked We could not cope with them all.’ by buildings that had collapsed.’ REBUILDING THE AREA Within two years of the earthquake, a lot of the damaged areas had been rebuilt (D). To make sure that the effects of any future earthquakes are reduced, the following measures have been put in place: • Making sure that new roads are wider • Leaving more space between buildings • Using building materials that do not catch fire so easily D Kobe city rebuilt two years after • Making buildings stronger and more flexible the earthquake • Not building on unstable ground Activities 1 Write a heading ‘The Kobe Earthquake – Japan’. Person Point Underneath the heading write down: – when it happened Local resident Buildings began to shake – how powerful it was and many collapsed – the effects on people – the effects on buildings. 4 a) Draw an outline sketch of photo B showing 2 Why might the effects have been worse if the how some roads were damaged. earthquake had happened between 8.00 and b) Put labels on your sketch to describe the 9.00 am? main points. (See page 154 of SKILLS in 3 Complete a table like the one started here, which geography.) describes one point made by each of the three 5 Explain how any one of the rebuilding ideas may people talking about what it was like to live make the area safer if there is another through the earthquake. earthquake in the future. 1 Living with earthquakes and volcanoes 13
  10. 10. What happened in the 2003 earthquake in Iran? > Learning about the effects of an earthquake in a developing country Iran Caspian > Understanding the effects of an earthquake in a developing Sea country Tehran I r a n On Friday 26 December 2003 at 5.27 pm a major earthquake hit the Kerman Iranian city of Bam, a city of 80,000 people (A). The city is famous for its Iraq Bam 2,000-year-old red brick citadel and fortress, which attracts thousands of tourists each year. The Gulf W H AT C AU S E D T H E E A RT H Q UA K E ? Saudi Arabia N The Iranian plate and the Arabian plate pushed together. This caused a shockwave which was the start of the earthquake (B). 0 400 Kilometres The following news reports describe what it was like in Bam after the A Bam, Iran earthquake. Afghanistan N Caspian Sea Eurasian Plate Tehran Iranian Plate Iraq I r a n Arabian Plate Bam Th e G ul f 0 400 Kilometres C Bam Citadel before the earthquake B Plate movement causing the earthquake OF BAM NCIENT CITY QUAKE ROCKS A day when an were killed yester Ove r 20,000 people m. With t Iranian city of Ba earthqu ake hit the ancien fears that royed, there are s of homes dest thousand homeless in the e from being left many more will di winter cold. people, with ty of over 80,000 Ba m is an ancient ci years old. It ings over 2,000 man y mud brick build e badly itals and both wer only has two hosp earthquake. D Bam Citadel after the earthquake damaged by the 14 geography 360° Foundation Book 3
  11. 11. S THOUSANDS EARTHQUAKE KILL are feared rning 40,000 people Just before dawn this mo scue volunteers, the dead. Re an ear thquake devastated amedics are city of Bam in Iran. Mud brick doctors and par and being flow n to the country to homes in the city ny of whom were help sur vivors, ma sur rounding villages everything. to have lost reduced to rubble and up CITY OF BAM DEST ROYED IN DEADLY EARTHQ UAKE Thousands of homes were more may die of cold or destroyed when an earthq threat uake of disease. The two hospita hit the ancient Iranian ls in city of the city have been damage Bam yesterday. Over d so 20,000 people cannot get the hel people were killed and p they many desperately need. D Emergency shelter after the earthquake BAM – ONE YEAR ON It often takes poor countries a long time to rebuild after an earthquake. A television reporter visited Bam a year after the earthquake and made the following notes: • There are still lots of homeless • Lots of new houses have been people. built. • Lots of people are still living in • Most of the roads have been tents on the edge of the city. cleared. • Piles of rubble are everywhere. Activities 1 Write the title ‘The Bam earthquake – Iran 2003’. Both _________ were damaged and people a) Copy out and complete the following sentences. had to be flown 100 miles for medical help. The number of people living in Bam is collapsed hospitals plates early _____________. brick shake built The ancient Citadel is _______ years old and 2 Copy out and complete the table below by adding made from _______ _______. four other types of structures that may have been b) Copy out the following passage, which damaged by the earthquake. describes what happened in the Bam Earthquake damage earthquake. Use the words in the box below to complete the passage. Houses Roads The earthquake happened because the Iranian and Arabian _________ moved together, causing the ground to __________. It happened __________ in the morning and many people 3 a) Why does it take a long time for poor countries were asleep in their red _________ houses. to get back to normal after an earthquake? Most houses were poorly _______ and b) List two things that have been done and two __________ during the earthquake. things that are still needed a year after the earthquake. 1 Living with earthquakes and volcanoes 15
  12. 12. What happens when a volcano erupts? > Learning about different types of erupted material > Understanding the effects of an erupting volcano W H AT I S A V O LC A N O ? A volcano is an opening or vent in the earth’s crust where different materials are able to reach the earth’s surface (A–D). W H AT S O RTS O F M ATE R I A L C A N R E AC H T H E E A RT H ’ S S U R FAC E ? Lots of different types of material can be forced up from inside the earth’s crust during a volcanic eruption. Not all volcanic eruptions are explosive. In places like Hawaii lava flows in channels and can be studied at quite close range. A Molten lava (liquid rock) can be: B Steam and volcanic dust often – thick and sticky and move quite slowly Types of material come out of small eruptions. – thin and runny and flow very quickly. erupted from the earth C Red hot ash is erupted from many D Volcanic bombs – large blocks of hot rock – can be volcanoes and is very dangerous. thrown hundreds of feet in the air during an eruption. 16 geography 360° Foundation Book 3
  13. 13. W H AT DA M A G E C A N A V O LC A N I C E RU P T I O N C AU S E ? Gas clouds can suffocate people. Lava flows destroy everything in their path. Volcanic bombs can destroy buildings. Ash can mix with water and form mud flows. These can move down hillsides at over 50 mph destroying anything in their way. Hot ash will burn people and cause fires. Rivers can be blocked by erupting material, causing flooding. Trees can be blown flat by a volcanic blast. Roads and bridges can be washed away. Villages and towns can be Animals and crops buried by flowing lava. can be destroyed. A R E A LL V O LC A N O E S AC T I V E ? Volcanoes can be active, dormant or extinct. Active volcanoes have erupted recently and are expected to erupt again. There are over a thousand active volcanoes, many around the edge of the Pacific Ocean. Dormant volcanoes have not erupted for many years but could still erupt. Extinct volcanoes are not expected to erupt again in the future. Activities 1 Copy out and complete the following sentences 3 Write a sentence about how volcanic eruptions (look back to page 7 to help you): can damage each of the following: Magma is … – People – Roads Lava is … – Buildings – Farmland 2 Copy out and complete the following table to show 4 Research task Use the internet (see Hotlinks, the different types of material that can come out page ii) to find two examples each of: of erupting volcanoes. – active volcanoes – dormant volcanoes Material erupted from the earth – extinct volcanoes. Steam 5 Use the internet (see Hotlinks, page ii) to locate Ash five volcanoes currently erupting. 1 Living with earthquakes and volcanoes 17
  14. 14. Case study: the eruption of Mount Nyiragongo, Congo > Understanding what it is like to live through a volcanic eruption > Finding out the problems of living with hazards in poor countries A Mount Nyiragongo, Congo On Thursday 17 January 2002 Mount Nyiragongo, a N volcano in Central Africa, began to erupt (map A). In the Central African Republic Sudan lakeside city of Goma, ten miles to the south, the local people had no idea of what was going to happen over Cameroon the next two days. Mount Nyiragongo is a steep-sided mountain, so when it Democra tic a erupted, the lava flowed like a river towards Goma. As the Republic of and Congo lava reached Goma, it began to cool, filling the streets Ug Gabon with thousands of tonnes of cooling rock (photo B). Goma Rwanda Bukava Burundi W H AT WA S I T L I K E L I V I N G Kinshasa T H RO U G H T H E E RU P T I O N ? Tan Kananga The following newspaper article and sources B and C z Mbuji-Mayi ani show what it was like to live through the eruption. a Angola Lubumbashi 0 400 Kilometres Key Nyiragongo Source: Developed by Lyn Topinka, Cascades Volcano Observatory people had of Goma lava and many The African city to run for their liv es. a volcanic ning nearly was lit up by By early this mor t as lava eruption last nigh 300,000 people had left e sides of looked like poured from th Goma – the city It Mount Nyiragongo. n the edge small vil- a ghost town. O destroyed many of the city the only airport e its way lages as it mad had been dest royed and the shore towards Goma, on many buildings could be ldings were of Lake Kivu. Bui seen burning. the red hot turned to ash by B Destruction in the main street of Goma 18 geography 360° Foundation Book 3
  15. 15. C Experiences during and after the eruption ‘Many people are living on the streets. They have no shelter and little food.’ ‘The lava flowed through Goma and Aid worker into Lake Kivu. Lots of people escaped by boat. Some said the lava had heated the lake up so much that it was like bath water!’ Local fireman ‘We had to leave our home. I tried to return a few days later but everything was destroyed.’ Local resident ‘I was working in the area. I could not believe the noise and the smell of chemicals as the lava flowed ‘The eruption was so through the streets of Goma.’ powerful it woke me up and Foreign worker shook my bed – and ‘Many local doctors stayed in I was fifteen miles away!’ the area during the eruption and Tourist in nearby town tried to help people. Thank God they are safe.’ Visiting doctor ‘I was told that the lava was flowing from Mount Nyiragongo at over thirty miles per hour!’ ‘There is no safe water for people to drink. Student living in Goma We are very worried about disease.’ Local health worker Activities 1 Copy out the following passage which explains 2 a) Choose a title for the photograph on the what happened in Goma. Use the words in the box opposite page (B). below to fill in the gaps. b) Describe three points from the photograph. When Mount Nyiragongo ___________ a flow of 3 Copy out and complete the table below using _________ moved towards the city of ________. It three more of the experiences in source C. moved quickly because of the __________ slopes. Experiences of the eruption The lava destroyed many farming __________ on Person Experience its way to Goma, forcing people to leave their homes. On the edge of the city the Local resident Had to leave home _____________ was destroyed, and many buildings could be seen ____________. The following day, the main streets of Goma were full 4 Why will it be difficult to get food and clean water of thousands of tonnes of cooling ____________. to the people of Goma? steep airport burning lava erupted villages rock Goma 1 Living with earthquakes and volcanoes 19
  16. 16. How can earthquakes and volcanoes be made less of a hazard? > Understanding that prediction, planning and preparation can reduce risks > Learning about some of the methods used to reduce the risks of earthquakes and volcanoes C A N E A RT H Q UA K E S B E P R E D I C TE D ? • We know that most earthquakes happen near the edges of plates so we can use instruments (A) to tell if anything is happening in these areas. • When there is movement underground: Emergency planning officer – gas is sometimes released ‘It’s not easy but there are – water levels change. things we can look out for • Small movements can be picked up and do.’ on a seismometer – this might tell us that an earthquake is on the way. A heavy weight at the top stops the building swaying as much A A laser detector Cross-bracing means that the PL ANNING FOR building can sway E A RT H Q UA K E S without collapsing The following measures can reduce the risks from earthquakes: A broad base makes the • Make sure bridges and roads are building more strong enough to withstand stable earthquakes. • Use building materials that don’t burn as easily. • Leave bigger spaces between buildings for emergency vehicles. Rubber pads absorb ground tremors ‘The biggest danger in an earthquake is caused by buildings collapsing or catching fire. It is possible to construct buildings that are earthquake proof – The TransAmerica B TransAmerica Pyramid, San Francisco Pyramid in San Francisco is a good example of this.’ 20 geography 360° Foundation Book 3
  17. 17. W H Y I S P R E PA R AT I O N I M P O RTA N T I N A N E A RT H Q UA K E Z O N E ? ! EPAREDur ■AhRED! BE PRou knowBEe yPREP C oose a safe place to she o wher sure y your hom lter in e e. ■ Mak pital is. cal hos family ■ Have spa lo in your re batteries ev eryone mobile phon for your e sure if an ■ Mak at to do e and a torc h. ws wh ■ Prepare a kno es. n earthquake ake strik fixed earthqu niture is emergency ki t – include fir your fur ver. materials an st-aid e sure topple o ■ Mak and cannot might need d other things you to walls er in to shelt to survive fo a fe place couple of da ra ose a s ys. ‘Preparation is not just making sure ■ Cho e. m that the ambulance, hospital, fire your ho and police service know what to do – it is also about preparing individual people. This could save your life.’ C Earthquake preparation leaflet W H AT A B O U T V O LC A N O E S ? Before volcanoes erupt there are often warning signs If you know an eruption is going to happen, emergency including: plans can be put in place. These might include: • small earth tremors • moving people away from danger • the side of a volcano begins to bulge or cracks • setting up emergency shelters with food, water and appear warm clothes • small eruptions giving off heat, ash or gas. • making sure emergency transportation is available. Activities 1 Copy out and complete the following sentences by 3 What things other than first-aid materials might adding the correct word from the box below: you put in an emergency earthquake kit? ______________ is about working out when 4 Copy out and complete the spider diagram to something is going to happen. show what might happen before an earthquake ______________ is about making sure buildings strikes. are well constructed. ______________ is about making sure people know what to do if an earthquake strikes. Warning signs PREPARATION PREDICTION PLANNING 2 a) Draw a sketch of the TransAmerica Pyramid (B). b) On your sketch write short notes explaining 5 Make up a poster to show how people should what has been done to make the building safer. prepare for an earthquake. Be sure it has: (See page 154 of SKILLS in geography.) – a clear heading – a number of points – some drawings and colour to make it attractive. 1 Living with earthquakes and volcanoes 21
  18. 18. What is a tsunami? > Understanding what causes a tsunami > Finding out what can be done to reduce the effects of a tsunami In Japanese the word ‘tsu’ means wave and ‘nami’ means harbour, so the word ‘tsunami’ really means ‘harbour wave’. It was called this because of FAC T F I LE giant waves hitting the Japanese coast. The highest recorded wave created by a tsunami hit Japan W H AT C AU S E S A TS U N A M I ? in 1921 and was just under Earthquakes or volcanoes create tsunamis. Sudden movements on the 90 metres high! seabed push water upwards and start a wave. In deep water the wave is Over 80 per cent of tsunamis quite small, but moves very fast – often up to 500 mph. As the wave gets occur in the Pacific Ocean. near to land, it slows down but gets much bigger. It swallows everything in its way and can totally destroy coastal areas (source A). H O W D O E S A TS U N A M I D E V E LO P ? 5 Coastal area flooded as 4 The wave gets the wave surges inland. bigger as water piles up behind it. 2 The seabed is moved up and down, creating a wave. 3 As the sea becomes ter w wa shallower, the wave Shallo increases in size. w n. ave do s the w 1 The seabed is bed slow shaken by an on sea Friction earthquake or volcano. Deep water A Development of a tsunami H I S TO R I C TS U N A M I S Alaska 1946 1964 1965 California 1896 Japan 1896 Hawaii Colombia 1906 Philippines 1976 Papua New Guinea 1998 Indonesia 1938 Sumatra 2004 Chile 1960 N 0 3000 Kilometres B Location of historic tsunamis C Devastated coastal area following a tsunami 22 geography 360° Foundation Book 3
  19. 19. H O W C A N Y O U P R E PA R E F O R A TS U N A M I ? Keeps a close look Warn people who out for earthquakes might be in danger To help some countries prepare for tsunamis, the Pacific Tsunami Warning System was set up. This involves twenty-four countries in the Pacific Ocean area. It is organised from the island of Hawaii, in so that it can the centre of the Pacific Ocean (B). P L A N N I N G F O R A TS U N A M I Tell governments In richer parts of the world, such as Japan, coastal Looks for changes when to move in sea level patterns people away from areas have been changed to help them cope with coastal areas tsunamis. The diagrams in source E show how a coastal area can be changed so that if a tsunami occurs, the damage will be much less. D Pacific Tsunami Warning System Without planning Area devastated by a tsunami Village Houses Possible height of tsunami wave Road Beach Normal sea level With planning Planted forest Houses Possible height of tsunami wave Sea wall Raised road Normal sea level Beach E How planning for a tsunami can help avoid disaster Activities 1 Draw a sketch like the following one. 2 What does the word ‘tsunami’ mean? 3 What has to happen for a tsunami to start? 4 Which part of the world gets the most tsunamis? water 5 What are the aims of the Pacific Tsunami Shallow Warning System? 6 Describe the ways that a coastal area can be Deep water changed to reduce the effect of a tsunami. Put the words in the box below on your sketch. Earthquake Small waves Large waves Buildings destroyed 1 Living with earthquakes and volcanoes 23
  20. 20. Case study: the Indian Ocean tsunami – December 2004 > Understanding that an undersea earthquake can affect places hundreds of miles away > Finding out about the causes and effects of the Indian Ocean tsunami On the 26 December 2004 one of the strongest earthquakes ever recorded happened near the coast of north-west Indonesia (photo A). The underwater earthquake sent huge waves racing across the Indian Ocean and even reached the coast of East Africa – 4,000 miles away. A Satellite image showing the W H AT C AU S E D T H E TS U N A M I ? developing Indian Ocean tsunami sian Eura te Pla N n ralia Aust Indo- late P 1 The Indo-Australian Plate suddenly moved about 2 The resulting earthquake pushed 20 metres under the 6 metres of water upwards, Indian Ocean. creating a massive wave. India ys ia Mala an ka Sri L atra Sum 3 As the wave reached the coastline it grew in height. n esia Indo B The cause of the tsunami Epicentre of earthquake 0 1000 Kilometres W H AT WA S T H E R E S U LT I N CO A S TA L FAC T F I LE AREAS? • The tsunami killed over 300,000 people. • Over 1 million homes were destroyed. • The waves travelled at over 400 mph out at sea – reducing to 30 mph near land. • The height of the wave was between 3 and 9 metres. C Tourists fleeing as the tsunami wave approaches 24 geography 360° Foundation Book 3
  21. 21. Map D shows the immediate effects of the tsunami as massive waves crashed onto the coastal areas surrounding the Indian Ocean. India Calcutta Dhaka Thailand Large area of the eastern coast I n d i a Western coast of southern swamped by waves, particularly the Bangladesh Thailand badly affected, Bombay cities of Madras and Pondicherry. Andhra Burma including the holiday resort Deaths also reported in the Andaman of Phuket and Phi Phi Island. and Nicobar Islands, and Kerala state. Pradesh Bay of Bengal Laos Vishakhapatnam Malaysia People reported to N have been swept Rangoon Thailand away from beaches Tamil near the northern Nadu city of Penang. Madras Andaman Bangkok Maldives Andaman Is Sea High waves and floods Pondicherry (India) inundate islands. Two-thirds of the low-lying Kerala capital, Male, reported to be INDIAN Gulf of under water. Trincomalee OCEAN Thailand Mutur Phuket Indonesia v e s Colombo Province of Aceh on Nicobar Is Phi Phi Island northern tip of Sri (India) Sumatra island badly Lanka l d i Penang hit, including capital Male Banda Aceh Banda Aceh. 3 hours 2 hours 1 hour M a l a y s i a Dozens of buildings M a destroyed in the initial earthquake before Sri Lanka floodwaters washed Wide stretch of eastern and southern coast over the region. devastated by massive waves, and national Sumatra disaster declared. Districts of Mutur and Trincomalee apparently Epicentre of earthquake 0 500 Kilometres inundated by waves as high as 6 metres. 9.6 kilometres below Part of the capital, Colombo, shut by floods. seabed 7.59 am local time. Indonesia D Immediate effects of the tsunami Source: NI Syndication Activities 1 Copy out the following points in the correct order 3 Put a title ‘The effects of the tsunami’. to explain what caused the tsunami: Copy out and complete the following table, which • The sea was pushed upwards. describes some of the effects of the tsunami in • The waves moved towards the land. different countries. • There was a massive earthquake. Counry Effects • Waves were created. Sri Lanka A lot of areas flooded 2 a) What are the names of the two plates that moved, creating the earthquake? A lot of damage b) By how much did the plates move? 1 Living with earthquakes and volcanoes 25
  22. 22. Living through the Indian Ocean tsunami > Learning about how it feels to experience a tsunami > Understanding that hazards can have both short- and long- term effects When the tsunami struck the coastal areas surrounding the Indian Ocean millions of people were affected, including thousands of holidaymakers who had gone to the area for a ‘sunshine break’ during the Christmas holidays. The following resources give an impression of what it was like to live through the tsunami. their Thousands of people were swept to the deaths yesterday as a giant wave hit holiday beaches of south-east Asia Beach resorts across the reported a low groaning area – from Thailand to Sri noise before the waves Lanka were ripped apart by crashed against the build- a wave of water up to ings. The waves were so nine metres high. powerful that they totally There was little warning as destroyed buildings and the wave of water swept picked up cars and trucks – across the area. People moving them miles inland. As millions of people were going about their daily lives, they w ere totally unaware of the horrors facing th em People were not to kn ow that the gentle swaying beaches, many based of skyscrapers in Sing on the fishing industry a- More recently, th . pore was the result of e tourist an industry has de earthquake which wa veloped s with large resorts about to bring a wall and of holiday homes water crashing down dotted on along the coas their homes. t. When Towns and villages ha the wave struck, man ve of these area y grown up near th s were e totally destroyed. 26 geography 360° Foundation Book 3
  23. 23. N 0 1000 Kilometres INDIA ‘We were sitting in our bedroom and heard an enormous roar. Seconds later the door burst open and the room filled up with water. We were THAILAND swept out of the windows, but managed to ‘We were on a diving boat and were thrown around by struggle towards higher land the waves. The boat was taken inland by the wave and stuck between – and safety.’ two buildings. We climbed to the roof of a hotel. We were lucky to survive.’ ‘I was just going for a swim in the pool when a giant wave appeared. The wave knocked me down several times – it was very strong. I was hit by trees, I n d i a tables and other things, but managed to struggle to safety. I am covered in Burma cuts and bruises, but am lucky to be alive – so many people in the area have lost their lives.’ P h i l i p p i n e s Thailand I n d i a n O c e a n Sri Lanka M a l a y s i a I n d o n e s i a SRI LANKA ‘There was no warning. The first wave crashed through the buildings – many of which collapsed. Everything was swept along by the waves – even cars and lorries.’ ‘The water levels are now going down, leaving a scene of total devastation. Most local people have lost their homes.’ A Interviews with British holidaymakers affected by the tsunami Activities 1 What information do the newspaper reports give 5 Write a short paragraph to describe the experience about: of holidaymakers in India, Thailand and Sri Lanka. – the size of the waves? 6 The following point was made in a radio interview – the power of the waves? by an aid worker: 2 What happened in Singapore to suggest that an ‘Many people are drinking dirty water and eating earthquake had occurred? food picked up from the streets. They are also having to sleep in the open.’ 3 Why do a lot of people live on the coast in this area? What problems might this cause for people in the next few weeks? 4 Describe what is happening in the photographs on the opposite page. 1 Living with earthquakes and volcanoes 27