describe the interaction of human activities with natural systems explain the causes of major events in natural systems that impact on humans describe the impact of natural disasters on humans living in the region evaluate responses made by governments, non-government organisations and community groups to natural disasters propose strategies to deal with the impact of natural disasters in the future. The structure of the Earth Civilization exists by geologic consent, subject to change without notice. Will Durant, US historian (1885-1981) This chapter examines plate tectonics as one of Earth's major natural systems. The interaction between plate tectonics and human activities is investigated through studies of the natural disasters associated with plate tectonics. These disasters do not respect human borders and are a threat to all people. Any explanation of plate tectonics requires a basic understanding of the internal structure of the Earth. Since the formation of the Earth about 4.6 billion years ago, the planet has cooled and separated into several different layers [4.1]. The solid inner core consists mostly of dense iron. A less dense layer of nickel and iron called the outer core surrounds the core. The next layer is the molten mantle, which has several distinct layers. The Earth's crust is the outermost layer surrounding the mantle. It is a thin layer of rocky material that is in a state of constant movement over time. Interactions between the two outer layers of the Earth determine the operation of plate tectonics. What is plate tectonics? the outermost layer of the Earth including the crust and the uppermost mantle The theory of plate tectonics was developed in the late 1960s to explain the .t.!l?.s.P!?®r?. dynamic processes of the Earth. According to plate tectonics, the lithosphere of the Earth consists of thin, rigid segments or plates of crust and the uppermost mantle. These lithospheric plates float like rafts on the deeper, molten layer of the mantle. The theory of plate tectonics offers a reasonable explanation for the process of plate evolution—their formation, movement and destruction. It shows that the Earth's surface is not a static grouping of land and water bodies, but an integrated system driven by materials and processes from the Earth's interior. As plate tectonics operates over time, it slowly and continuously changes the sizes, shapes and locations of the world's continents and oceans. Plate tectonics only gained widespread acceptance in the late 1950s and early 1960s. Prior to this, the processes causing tectonic forces were unknown and subject to speculation. The development of the theory of plate tectonics and the important processes that underpin it are a necessary starting point to understand how this natural system operates. [4.1] The internal layers of the Earth Crust Mantle Inner core Outer core to all Learning activitie Explain in your own words Will Durant's comments at the start of the chapter. Describe the internal structure of the Earth. What is the lithosphere? What does the theory of plate tectonics tell us about the Earth's surface? Evolution of the theory of plate tectonics Since the early map makers of the 1400s and 1500s, many people had noticed that the shape of the continents fitted together like pieces in a giant super-continental jigsaw puzzle. The first modern scientist to propose that the continents had once been joined was Alfred Wegener, a German meteorologist. The theory of continental drift In 1912, Wegener presented a detailed theory of continental drift. He proposed that the continents had once been joined as a super-continent he called Pangaea [4.2]. Wegener's evidence included common ancient glaciations, similar mountain ranges, fold belts, rock types and fossils from places where continents on different sides of large oceans fitted together. He proposed that the continents had drifted apart by sliding over the ocean floor. However, geologists rejected Wegener's theory saying that the ocean crust was not strong enough to support the continents and there would be too much frictional resistance for any movement to occur. In spite of this, evidence to support continental drift gradually began to accumulate, first in the form of studies of the Earth's magnetic field. 1.2] The evolution of the continents from the super-continent Pangaea Palaeomagnetism Palaeomagnetism is the history of the Earth's magnetic field. In the 1950s and 1960s, geologists discovered that when rocks cool and solidify, the alignment of magnetic minerals, such as magnetite, takes on the orientation of the magnetic field at the time the rock was cooling. Studies on rocks of various ages in Europe and North America showed that the magnetic pole had apparently moved through time. However, the path of the magnetic poles for Europe and North America wert| different, suggesting that the continents had moved relative to each other through time. This was confirmed by studies on other continents. The next step in the acceptance of the plate tectonics theory was the discovery of the mechanism for how the continents moved. This was to come from studying the sea bed. earni What evidence did Wegener use to show that the continents had once been joined together? What is Pangaea? Why did geologists initially reject Wegener's theory? How did palaeomagnetism help to prove that the continents had moved over time? Sea-floor spreading During World War II, geologists working for the United States military made some significant discoveries while studying the ocean floors looking for hiding places for submarines. They found two important topographic features on ocean floors: o oceanic ridges—these long ridges were found in the middle of the Atlantic Ocean and in the eastern part of the Pacific Ocean o oceanic trenches—these deep trenches were found along the edges of continents, especially in the Pacific Ocean. The second major discovery was made while towing magnetometers behind ships searching for submarines. The records for the magnetometers showed that there were parallel bands of alternating high and low magnetism like mirror images on either side of the oceanic ridges. These reversals of magnetism correspond to reversals in the polarity of the Earth's magnetic field. Through their study of lava flows, geologists have established that the Earth's north magnetic pole and the south magnetic pole periodically reverse over geologically short time periods. The age of volcanic rocks from around the world has been dated and used to establish a global magnetic time scale. The age of the rocks on either side of the oceanic ridges gets progressively older further away from the ridge. The youngest rocks are at the oceanic ridges where magma rises to the surface creating new oceanic lithosphere crust. The ridges are in fact active submarine volcanoes. This information lead to the theory of sea-floor spreading, which partly explains the movement mechanism of lithospheric plates. Continental drift appears to be due to the process of sea-floor spreading [4.3]. New lithospheric material is continually intruding upwards and pushing outwards at the boundaries of lithospheric plates like two super conveyor belt systems moving in opposite directions. Geologists proposed that if lithospheric material was continuously being created at the mid-oceanic ridges and moving outwards, then it must be continuously being destroyed at the edges of the lithospheric plates [4.4J. [4.3] A theoretical model of sea-floor spreading and magnetic striping at a mid-oceanic ridge: (a) a spreading ridge about 5 million years ago, (b) about 2 to 3 million years ago, and (c) present-day [4.4] New oceanic lithosphere is continuously created at the mid-oceanic ridges and spreads outwards over time Mid-ocean ridge Normal magnetic polarity Ľ Reversed magnetic polarity oceanic trenches B*Pval|eys in the ocean J edges of tectonic 5 where oceanic re subducts back into the mantle Destructive oceanic trenches While oceanic ridges continually create new material and expand the oceans, this cannot continue indefinitely. The oceanic lithosphere is ultimately destroyed and recycled into the mantle at the oceanic trenches. Here, the oceanic lithosphere subducts (slides downwards), fractures and produces progressively deeper and deeper earthquakes as it continues its slow descent into the molten mantle. As the material sinks and melts, plumes of magma rise up through fissures and fault lines in the overlying continental lithosphere to create chains of volcanoes parallel to the oceanic trenches. These tectonically unstable landforms are the visible product of the destructive margins of lithosphcric plates. The Pacific Ring of Fire—one of the world's best-known destructive oceanic trenches—is marked by active volcanoes and earthquake activity [4.5]. ! The Pacific Ring of marks the destructive ycling) margins of Pacific plate. It is the sttectonically and canically active region subduction zone the boundary where one continental plate meets another plate and sinks below it Subduction zones at the edge of tectonic plates are long, thin zones of concentrated tectonic activity. Typically, subduction zones are no more than 100 kilometres wide. The total length of the world's subduction zones is about 30 500 kilometres. The total global area of subduction zones is about 2.6 million square kilometres. This is about the size of Argentina. Learninci activities -oceanic ridges? >lain how the lithospheric plates move? trenches? ppens at oceanic trenches. : sea-floor spreading works. Describe how the Pacific Ring of Fire got its name. How do they help What are ocear Describe what I Explain how the theory i The theory of plate tectonics The theory of plate tectonics builds upon the theory of continental drift, the theory of sea-floor spreading and information on earthquake and volcanic activity at subduction zones located at tectonic plate boundaries. Plate tectonics has revolutionised the study of the Earth as an integrated natural system. did you know? of oceanic lithosphere sometimes rise above the surface of the ocean like toothpaste squeezed from a tube. Examples include Iceland and the Australian territories of Heard and Macquarie Islands. Types of lithosphere The Earth's lithospheric plates consist of two basic types of lithospheric building blocks: o oceanic lithosphere (sima)—thin, (around 10 kilometres) dense crust made up of younger volcanic basalt (less than 300 million years old) o continental lithosphere (sial)—thicker, (sometimes 20-80 kilometres) less dense crust made up of older granites, sedimentary, volcanic and metamorphic rocks (as much as two billion years old). Continental lithosphere is not subducted and recycled in the mantle. It only changes size, shape and position, and can fragment and combine. Oceanic lithosphere is temporary (geologically speaking) because it is always destroyed by subduction. That explains why the oldest oceanic lithosphere is less than 300 million years old. The theory of plate tectonics explains the interactions between ocean and continental lithospheric plates, and the occurrence of volcanoes and earthquakes over the Earth. Lithospheric plates Geologists now agree that the lithosphere consists of several irregular plates that are joined along their edges. These rigid lithospheric plates act like slow-moving armour plating across the continents and oceanic floors. While the plates have some flexibility, they generally behave as rigid bodies and only deform along plate boundaries. CHAPTER4 Plate tectonics: the moving Earth 109 It is worth remembering that the present pattern of tectonic plates shown in [4.6] is only the most recent pattern of tectonic plates since Pangaea formed about 300 to 500 million years ago. Geologists believe that there were probably many other combinations of lithospheric plates and continents before then. [4.6] Global pattern of tectonic plates What drives plate tectonics? Powerful convection currents in the mantle move the lithospheric plates across the surface of the Earth. In the process, these currents redistribute the huge amounts of heat generated by the formation of the planet and the natural radioactive decay of materials, such as uranium and thorium, from the interior of the Earth to the surface. The movement of the convection currents is very slow, measured in only millimetres per year. The currents consist of a soup of soft, plastic (easily moulded), molten rocks that rise from the lower mantle about 1600 kilometres down. When they reach to within 4 to 32 kilometres of the surface, they encounter the rigid and brittle layer of the Earth's crust called the lithosphere. Here, the currents slow down and sometimes stop for a while before once again sinking back to the depths. Geologists theorise that the sinking of dense oceanic lithosphere at subduction trenches is also a main driving mechanism of plate tectonics. They call this destructive tectonic process at the margins of plates 'slab pull'. The creative tectonic process at mid-oceanic ridges is called 'ridge push [4.7]. Just how plates move is still unknown. asthenosphere [4.7J Powerful convection currents drive plate tectonics as well as 'slab pull' and 'ridge push' tho zone beneath the relatively rigid lithosphere where fluid molten rock has maximum plasticity or flowing ability. Mid-oceanic ridge (Ridge push) Oceanic trench Lithospheric plate / (Slab Oceanic trench Learni did you knOW' Why has plate tectonics revolutionised the study of the Earth? Describe the two basic types of lithosphere. Why is continental lithosphere regarded as geologically permanent while oceanic lithosphere is regarded as temporary? List the major tectonic plates on which the continents are located. Explain how convection currents result in the movement of lithospheric plates. What is the asthenosphere? Plate boundaries Tectonic plate boundaries were discovered by plotting volcanoes and earthquake activity on a world map. There are four types of plate boundaries based upon their relative movements. Plate movements occur in relatively narrow zones between plates where the tectonic forces with potential risks to humans are concentrated. 1 Divergent boundaries—where adjacent plates move away from each other as new oceanic lithosphere is created. The mid-oceanic ridges are spreading plate boundaries [4.8]. One of the best know divergent boundaries is the Mid-Atlantic Ridge, which spreads apart at a rate of about 2.5 centimetres per year or 25 kilometres per million years. 2 Convergent boundaries—where plates collide into each other and one plate is destroyed as it subducts under the other. There are three types of convergent boundaries, depending on the type of lithosphere involved. See [4.10], [4.11] and [4.12]. largest known concentration of active volcanoes. They found 1133 volcanoes on the sea floor in the South Pacific in an area about the size of Wales. CHAPTER4 Plate tectonics: the moving Earth 111 you know? through the Irthosphere to form volcanoes. As the lithospheric plate moves, the old volcanoes become extinct and the hot spots create younger volcanoes. The islands of Hawaii were created in this way. [4.13] The San Andreas fault zone in California is a transform tectonic plate boundary -...............- * % V*W Mountain range . High plateau [4.12] Continental-continental convergence, e.g. the Indo-Australian Plate colliding with the Eurasian Plate to form the Himalayas Transform boundaries—where the plates slide past each other, neither creating nor destroying the plates. Most transform boundaries are in the oceanic plates, where they are called fracture zones. The San Andreas fault zone in California is a rare example of a transform boundary on land [4.13]. Here, the North American Plate is sliding horizontally past the Pacific Plate at about 5 centimetres per year. It produces many shallow earthquakes that have destroyed property and taken many lives. Plate boundary zones—where plate boundaries and interactions arc uncertain because they extend over a wider area. An example of this is the region between the Eurasian and African plates where there are also several microplates. These zones tend to have more complicated geology and earthquake patterns. How were tectonic plate boundaries found? List the four main types of plate boundaries. What type of boundary are mid-oceanic ridges? Describe what happens at convergent plate boundaries Name the three types of convergent boundaries and give an example of each one Why are transform boundaries sometimes called conservative (rather than destructive) plate boundaries? In what ways are plate boundary zones different from other types of plate boundaries? mm Interaction of human activities with plate tectonics Humans gain many long-term benefits from living near plate tectonic boundaries, but they also have to deal with occasional short-term natural hazards and disasters, such as volcanic eruptions, earthquakes and tsunamis. Benefits of plate tectonics for human activities Present and past tectonic plate boundaries have an abundance of natural resources, such as fertile soils, biodiversity, minerals and energy. Humans have long used these resources and concentrated human settlement in these areas. [4.14] Natural resources of plate boundaries orographic rainfall rainfall produced by condensation around mountains geothermal energy Injy extracted Torn the [tin underground rocks and fluids Natural resources Characteristics Fertile soils Volcanic soils break down to produce some of the most fertile soils on Earth, rich in iron and magnesium. Greater crop production leads to higher population densities in volcanic areas. High biodiversity Volcanic regions generally have a greater biodiversity than non-volranic regions. The high altitude of many volcanoes also produces . As a result, natural vegetation and crops grow quickly and support a wide variety of anmal species. Mineral deposits Most valuable metallic mineral ores mined in the world are associated with past volcanic processes. Minerals such as gold, silver, copper, lead and zinc are concentrated by tectonic activity. Fossil fuels Coal, oil and natural gas are produced in geologic basins formed by plate tectonic processes. Geothermal energy Steam from active volcanic regions and underground rocks can be used to generate electricity and supply hot water and heating needs. More than 70 per cent of Iceland's homes are heated with [4.15] New Zealand generates electricity from geothermal power. Adverse impacts of plate tectonics for human activities Plate tectonics are responsible for the following natural hazards: ° volcanic activity o earthquakes o tsunamis. It is important to note that the effects of these individual natural hazards on humans occur over relatively short periods of time compared with the geological time scale of plate tectonics. Throughout human history, millions of people have been exposed to the effects of these natural hazards because they have chosen to live in close proximity to tectonic plate boundaries. Volcanic activity Since the year 1600 bcf (Before Common Era), nearly 300 000 people have been killed by volcanic eruptions. The Smithsonian Institute estimates that there are 1511 'active' volcanoes across the Earth, and many more dormant ones that could reactivate at any moment. Volcanoes cause problems for human activities in several ways: o Tephra (from the Greek word for ash), the exploded material (hot ash, rocks and lumps of semi-solidified lava from a volcano), may aerially bombard human settlement and cause loss of life and property damage. In 79 ce, Mount Vesuvius buried the cities of Pompeii and Herculaneum. ° Lava flows may engulf settlements; smother crops and roads, start fires and trap people. Around Mount Etna in Sicily, bulldozers are sometimes used to channel small lava flows so they cause less damage. In Hawaii, lava flows from the Kilauea volcano regularly bury villages, roads and property. o Pyroclastic eruptions are the fast-moving clouds of lava, ash and volcanic gases that may suffocate and incinerate people and animals as they bury everything in their path. In 1902, pyroclastic eruptions from Mount Pelee in Martinique killed Nine countries contain more than 90 per cent of the active volcanoes or volcanoes that have erupted in recent history—Indonesia, Japan, the United States of America, Russia, Chile, the Philippines, New Guinea, New Zealand and Nicaragua. [4.16] An active volcano erupts CHAPTER4 Plate tectonics: the moving Earth 115 i you he occurred in 179: he Unzen volcano, .metres east of ki. erupted and more than 15000 Unzen is one of live volcanoes in 28 000 inhabitants of St Pierre. Pyroclastic eruptions and mudflows account for most deaths caused by volcanoes. o Mudflows on the steep sides of volcanoes carry masses of water-loosened volcanic soil, mud and ash and may bury settlements and wash them away. The Javanese name 'lahars' is given to these natural disasters because they are common on the heavily populated and extremely volcanic Indonesian island. o Poisonous gases such as carbon monoxide, sulphur dioxide, carbon dioxide and hydrochloric acid may be released during eruptions and suffocate and kill people and animals. In 1986, a minor disturbance in a volcanic crater lake called Lake Nyos in Cameroon, Africa, released about one cubic kilometre of carbon dioxide gas that killed 1700 people in nearby villages, thousands of cattle and even more wild birds and animals. ° Erupting volcanoes near glaciers may melt the ice and release floods of water and mud that may drown people. This happened in 1985 in Colombia where 23 000 people were killed in a village when the Nevada del Ruiz volcano melted a glacier. Volcanoes may also release water from crater lakes that may flood surrounding villages. Predicting volcanic activity Around the world, vulcanologists and seismologists study the seismic activities, gas emissions and chemical composition of rocks from many active volcanoes and fault zones close to human settlements. They aim to predict eruptions and earthquakes so that people can be evacuated and lives saved. However, at present, no reliable vulcanologists method for predicting volcanic eruptions and earthquakes has been developed. As a scientists who study result, despite large advances in our knowledge of plate tectonics, it is not possible volcanoes to ensure the safety of humans due to the unpredictability of tectonic processes. Learni What are three natural hazards associated with living near tectonic plate boundaries? List five main benefits that arise from living near tectonic plate boundaries. Outline the ways that volcanic activity can create natural hazards for humans. How does a lava flow differ from a mudflow? Describe how scientists study earthquakes and volcanoes. Why do scientists want to predict volcanic eruptions and earthquakes? 1 seismologists sntists wno study hquakes or earth vibrations seismic (anything related "hquakes or earth vibrations Earthquakes Earthquakes are caused by a sudden release of built-up pressure in tectonic plates. When energy is released, seismic vibrations radiate outwards from the earthquake focus or rupture point. The point on the surface directly above the focus is the epicentre of the earthquake. The huge amounts of energy released by a major earthquake can cause damage up to thousands of kilometres away from the epicentre. Smaller aftershock vibrations can last for months as the tectonic plates readjust. Although scientists know how most earthquakes occur, they are uncertain about predicting when they will occur and how large they might be. did yOU knOW* Where do most earthquakes occur? Most earthquake activity is concentrated at tectonic plate boundaries. About 80 per cent of earthquakes occur in the Pacific region, 15 per cent in the Mediterranean and Asian regions and only five per cent occur in the mid-oceanic ridges. While earthquake activity can also occur away from tectonic plate boundaries, especially along fault lines or weaker areas in the Earth's crust, it is generally less frequent and severe than at tectonic boundaries [4.17]. Earthquake disasters Earthquakes have caused the world's greatest disasters. They flatten buildings and kill their occupants, rupture gas pipes, which in turn cause serious fires, and create widespread devastation. Earthquakes can also trigger dangerous tsunamis, | landslides and volcanic activity. Table [4.18] shows the 10 deadliest earthquakes of the last 100 years. [4.17] Most earthquakes are concentrated into narrow, tectonically active zones Asia North (^'Px ' America S \ , South 1 S America I \ lire Tectonic Plates Earthquakes > 0 2000 4000 km [4.18] The 10 deadliest earthquakes of the last 100 years This figure includes the number killed and missing in the tsunami triggered by the earthquake. Many thousands were killed in the Great Tokyo Fire caused by the earthquake. Date Location Fatalities Magnitude 1976 China, Tangshan 255000 7.5 2004 Indonesia, off Sumatra 232010* 9.0 1927 China, near Xining 200000 Not available 1920 China, Gansu 200000 8.6 1923 Japan, Kanto 143000** Not available 1948 Turkmenistan 110000 ■■BS 1908 Italy, Messina 70000-100000 (est.) 7.2 1932 China, Gansu 70000 7.6 1970 Peru 66000 7.9 1935 Pakistan, Quetta 30000-60000 (est.) [4.19] Devastation in Bam, Iran, caused by the 2003 earthquake Strategies to deal with earthquakes In an attempt to minimise the risk of earthquake damage, many countries such as Japan and the United States have incorporated strict building codes that are designed to minimise earthquake damage. Large skyscrapers have earthquake-buffering devices that minimise the violent shaking motion that causes buildings to collapse. In some areas, constant seismic monitoring and sophisticated disaster warning systems are in place, but there is little anyone can do until early warning prediction systems are improved. In 2006, the Japanese research ship Cbikyu started drilling seven kilometres into the seabed in an area where tectonic plates overlap. One of the aims of the mission is to find out about the origin of earthquakes in the mantle. Scientists hop the research will provide Japan and East Asia with the first effective earthquake prediction system. If the system is successful, it may be tried in other regions. earninq activities What causes an earthquake? What is the difference between the focus and the epicentre of an earthquake? What are aftershocks? Describe the global distribution of earthquakes and their spatial association with tectonic plate boundaries. Describe the different ways that earthquakes can kill people Where was the deadliest earthquake in the last 100 years and how many people were killed? Describe how building strategies may reduce loss of life in earthquakes. Why is the Japanese research ship Chikyu drilling in the sea floor? Tsunamis Tsunamis or seismic sea waves are caused by disturbances of the ocean surface as a result of volcanic eruption, earthquakes, coastal or submarine landslides or asteroid/meteorite impacts. The word 'tsunami' comes from two Japanese words meaning 'harbour wave'. A tsunami is not a single wave, but a series of waves witl enormous energy and momentum. Tsunamis travel outwards from the original disturbance zone at speeds of more than 800 kilometres per hour. Upon reaching land, the waves greatly increase in height and cause massive destruction, loss of life and property. The landfall of transoceanic tsunami waves can be thousands of kilometres from the original disturbance, so they represent a disaster threat to distant coastal communities. The Krakatau tsunami of 1883 The severe 1883 eruption of Krakatau volcano, located in the Sunda Straits between Java and Sumatra islands in Indonesia, created a series of tsunami waves up to 40 metres high. Almost all of the 36417 people who died were killed by the tsunamis created as the volcano blew itself to pieces. The sound of the great Krakatau explosion was heard nearly 5000 kilometres away and the tsunami travelled across the Indian Ocean to India, Australia, Madagascar and Africa. The Aitape, PNG tsunami of 1998 Earthquakes are the most common cause of tsunamis. They can also trigger landslides on land and underwater that in turn generate tsunamis. The Aitape tsunami hit the village of Aitape on the north coast region of Papua New Guinea (PNG) in 1998. The primary cause of this tsunami was a magnitude 7.0 earthquake that caused a submarine landslide. The landslide displaced the ocean surface and the resulting tsunami killed over 2000 people, destroyed houses and infrastructure, and altered the environment around the village [4.201. did you knOW? mistakenly called 'tidal waves'. However, they have nothing to do with tides. Strictly speaking, a 'tidal wave' or 'tidal bore' is the small wave formed by an incoming tide as it travels up a river estuary against the direction of the current. The tidal wave or bore that occurs on the Qiantang River in China is up to nine metres high and travels at up to 40 kilometres per hour. Another well-known example occurs in the estuary of the Severn River in England. [4.20] Part of the village of Aitape destroyed by a tsunami in 1998 Tsunamis in Australia According to Geoscience Australia, a tsunami affects the Australian coastline about once every two years. Fortunately, most are insignificant and are classified as low risk. However, Australia's north-west coastline has a moderate tsunami risk classification because of its proximity to the earthquake and volcanic activity resulting from the tectonic plate boundary lying across the Indonesian archipelago [4.21]. Evidence of large tsunamis that affected Australia in the past can be found in deposits of coastal materials 20-30 metres above the present sea level and many kilometres inland. The Great Barrier Reef off Queensland's coastline may offer some protection from tsunamis originating in the Pacific Ocean region. Similarly, the islands of New Zealand may also offer some protection from tsunamis originating off the South America coastline. [4.21] Tsunami risk assessment map of Australia [4.22] Tsunami warning information sign TSUNAMI HAZARD ZONE did you know Q Strategies to deal with tsunamis The obvious strategy in dealing with tsunamis is to avoid them. In order to do this, people living in coastal areas need advance warning of when a tsunami is going to strike. Most tsunamis occur in the Pacific region because of the tectonically active Pacific Ring of Fire. As a result, the Pacific Ocean Tsunami Warning System (POTWS) was established in 1965. It has 26 member nations that rely upon seismic-monitoring stations and sea-level gauges located around the Pacific. These devices measure earthquakes and abnormal changes in sea levels. The headquarters in Hawaii issue warnings for potential tsunamis to nations in the Pacific Basin. Once a tsunami is detected, the path is calculated and arrival times are estimated using travel-time maps. The potentially vulnerable coastal areas are identified and warnings issued. However, in order for a tsunami warning to be effective, a tsunami risk assessment for coastlines is needed. According to Geoscience Australia, the risk assessment looks at: the likelihood of an event that may cause a tsunami the expected location and size of an event the shape of the sea floor where an event may take place the shape of the coastal land that may be affected by a resulting tsunami the presence of any headlands or harbours in the region that may cause a tsunami to change direction. This risk assessment information is used to predict the potential speed, direction, height and destructiveness of any tsunami that may affect an area. In Australia, information on tsunamis is first gathered by Geoscience Australia seismologists who immediately notify Emergency Management Australia (EMA) staff. The EMA notifies Australian authorities and Pacific island nations at risk of tsunami damage. o o o o What are tsunamis? What causes tsunamis? Explain why tsunamis can threaten places far away from their source area. Outline the differences between tsunamis and tidal waves. Describe the Krakatau tsunami and its effects. What happened with the Aitape tsunami in PNG? Why does Australia's north-west coastline have a moderate tsunami risk classification? Describe how the Pacific Ocean Tsumani Warning System (POTWS) operates. What does a tsunami risk assessment for coastlines entail? Sample study: the 2004 Indian Ocean tsunami The 2004 Indian Ocean tsunami on 26 December was one of the world's greatest natural disasters. It affected some of the poorest nations in the world and prompted an unprecedented global response for aid. The tsunami was the deadliest in recorded history with more than 200000 people killed. It also caused severe economic and environmental damage [4.23]. Richter scale A logarithmic scale indicating the magnitude or strength of an earthquake. It was developed in 1935 by Charles Richter in collaboration with Beno Gutenberg, both of the California institute of Technology. [4.23] The Indian Ocean tsunami struck without warning and caused great loss of life and devastation Factors contributing to the development of the tsunami A severe 'megathrust' earthquake that measured 9.15 on the Richter scale triggered the 2004 Indian Ocean tsunami. The earthquake occurred in a fault line between the mobile Indo-Australian Plate and the stationary Eurasian Plate. See figure [4.6]. The epicentre of the earthquake was 250 kilometres off the northwestern coast of Sumatra in Indonesia. The Indo-Australian Plate is constantly moving northwards and colliding with the Eurasian Plate at the rate your fingernails grow (around 5-6 centimetres per year). In addition, it is sliding along and subducting under the Eurasian Plate. This tectonic movement generates great forces in these two tectonic plates. Earthquakes in this area are common and they occur when pressure is released along the tectonic boundary. On 26 December 2004, a slab of the Earth's crust 960 kilometres long by 250 kilometres wide slipped between 8 and 15 metres. This rupturing of the sea floor generated the earthquake, and displaced millions of tonnes of water that created the tsunami [4.24]. The earthquake was the world's most severe in 40 years. The tsunami spread CHAPTER4 Plate tectonics: the moving Earth out as a series of long waves from the epicentre of the earthquake and caused severe devastation in Asia and as far away as Africa. Once formed, the tsunami travelled at about 800 kilometres per hour and hit the coast of the Indonesian province of Aceh on the island of Sumatra 15 minutes later. It continued more than 4800 kilometres across the Indian Ocean and hit the coast of Somalia in Africa less than seven hours later. Waves and sea level increases of up to 30 metres were recorded in some places. [4.24] How the 2004 Indian Ocean tsunami was formed Sea floor Indo-Australian Plate Eurasian Plate Sea surface Sea floor t Earthquake Sea surface Sea floor Before earthquake Earthquake occurs Faulting pushes ocean up Tsunami-generated waves move outward [4.25] Radar imaging of the tsunami two hours after the earthquake Sea surface Height small in deep ocean Sea floor Height large at coast Tsunami wave height grows towards shore 80' 90" 100' 110' 120' 80 B 60 r 40 s I 20 5) Earthquake epicentre I___ Earthquake/tsumami-affected countries Why was the 2004 Indian Ocean tsunami so significant as a natural disaster? Explain what caused the earthquake that triggered the tsunami. Which countries were affected by the tsunami? Why were some countries in the Indian Ocean not affected by the tsunami? Impacts of the 2004 Indian Ocean tsunami Accurate estimates are impossible to obtain in some cases due to poor records and victims being washed out to sea. Citizens (mostly tourists) from more than 501 countries around the world were killed by the tsunami. Germany and Sweden lost more than 500 citizens in the disaster. Twenty-five Australians were killed and one) was still unaccounted for six months later. [4.27] Estimated human impacts Country where deaths occured Deaths Missing Displaced Indonesia >130000 >37000 >500000 Sri Lanka 31000 5 637 573 000 India 12 405 5 600 380000 Thailand 5 399 MHBWM1HHBBBBM 3 000 HHHH Somalia 298 5000 Maldives 82 26 22 000 Malaysia Burma (Myanmar) Tanzania Seychelles Bangladesh South Africa Kenya Yemen 200 3200 >17933: >51426 >1484200 Impacts on children The United Nati ons Children's Fund estimated that up to 1.5 million children were affected by the tsunami. A large percentage of the tsunami casualties were children because they make up more than a third of the population in the Asian countries affected by the tsunami [4.29]. CHAPTER 4 Plate tectonics: the moving Earth 123 the west coast of Aceh after More than 30000 children lost one or both parents and many more children lost other family members. The Save the Children Fund estimated that more than 150000 children were homeless and 2000 were separated from their parents in Aceh. Many organisations expressed fears that criminals, such as child traffickers, could exploit orphaned and displaced children. Surviving children require ongoing help to cope with psychological and emotional trauma. Environmental impacts The tsunami's giant waves (some over 10 metres high) destroyed many coastal mangrove forests, which protect the coast from erosion. Twenty per cent of sea grass beds around Aceh were damaged. Mangroves and sea grass beds are vital fish habitats. The tsunami damaged coral reefs in some areas by breaking off large pieces and smothering reefs in sediment and debris. Thirty per cent of coral reefs around Aceh were damaged. Coral reefs in the Asian region were already stressed by dynamite fishing and overfishing. Many fishermen depend on coral reefs for food. Coastal farmland and water supplies were flooded by salt water and contaminated with pollution from sewage, industrial chemicals and dead bodies. Asian rainforests were cleared to provide timber to rebuild houses and this led to increased run-off with silt carried into the ocean where it affected coral reefs. Economic impacts Houses, farms, industries and infrastructure in affected regions were largely destroyed and will take years to rebuild. The local fishing industries had more than 60 per cent of their boats destroyed. Agricultural crops in coastal areas were wiped out and rice fields were flooded with salt water making them useless for farming [4.30]. Economic growth estimates for 2005 were revised downwards for most tsunami-affected regions and countries. For example, Sri Lanka's economic growth was downgraded from five to four per cent for 2005. Indonesia requested that its external debt repayments be suspended until 2006. Tourist earnings slumped after the tsunami as tourists feared staying at coastal resorts. The Maldives is more dependent on tourism revenue than any other tsunami-affected country with 42 per cent of its gross domestic product coming from tourism. Economic impact on Indonesia In January 2005, the Minister of State for National Development Planning in Indonesia announced preliminary figures of economic damages and losses in Indonesia totalling rupee 42.7 trillion (A$5.7 billion). The damage included: o 1.3 million homes and buildings o 8 ports o 4 fuel depots 0 85 per cent of the water supply system o 92 per cent of the sanitation system o 120 kilometres of roads o 18 bridges. Since January 2005, the economic costs have increased as the full scale of the disaster became apparent. The infrastructure of Aceh will take many years to rebuild. [4.31] Banda Aceh before and after images 'BEFORE TSUNAMI CHAPTER 4 Plate tectonics: the moving Earth [4.32] Fishing boat carried into a village street in Sri Lanka [4.33] Banda Aceh was 'Ground Zero' for the 2004 Indian Ocean tsunami earninq activities Name the eight nations that suffered the most as a result of the tsunami. Why are accurate estimates of casualties impossible to obtain in some cases? Describe the impacts of the tsunami on children. Outline the main environmental impacts of the tsunami. What were the economic impacts of the tsunami? Why is the economic impact of the tsunami upon Indonesia likely to take many years to repair? Strategies in response to the tsunami The sheer scale of the 2004 Indian Ocean tsunami disaster shocked and united the world in an effort to help the survivors. Graphic images of dead bodies, destroyed buildings, orphaned children and desperate human suffering from more than 10 countries lead to an unprecedented international aid response. United Nations' agencies, non-government organisations (NGOs), foreign governments and many other organisations started humanitarian and emergency relief operations in the devastated regions. According to the US Agency for International Development, there are four phases in the provision of disaster relief. The first two phases occur immediately after a disaster. Phases 3 and 4 occur in the medium and longer term. [4.34] Disaster relief phases Ph hase 1—Emergency life saving Local people, government officials, armed forces and volunteer relief workers from many nations searched for the missing, cared for the sick and injured and buried the dead, sometimes in mass graves. The task was urgent because the hot, tropical climate and the large numbers of victims increased the threat of diseases, such as cholera, striking the survivors. Emergency hospitals, first aid centres, supply lines and communications networks were established. The immediate needs of the survivors included supplying food, safe drinking water, clothing, shelter and medicine. [4.35] Helicopters searched for survivors and provided emergency supplies in remote areas HHi^HHillHHHHBHiHBBHH^HHH^HH ■ I Phase 2—Relief efforts The survivors needed temporary shelter and a clean water supply to prevent disease outbreaks. Generators for electricity were set up and survivors were supplied with food, clothing and medical help. The huge cleanup operation began, often with the help of machinery. [4.36] Tsunami survivors were housed in an emergency tent village I Phase 3—Rehabilitation In this phase, temporary housing and schools need to be built. Utilities such as water, sewage and electricity need to be reestablished. Local businesses and sbopkeepers need help to start again. [4.37] Rehabilitation of buildings damaged by the tsunami nearGalle, Sri Lanka Phase 4—Reconstruction In this long-term phase, permanent houses, factories and businesses are rebuilt and services, such as hospitals and schools are restored. Infrastructure, such as roads, bridges, railways and airports, is also rebuilt and residents receive help to find permanent employment. [4.38] Local and international governments combine to support the rebuilding of services in one of the worst affected areas in Sri Lanka A II RECONSTRUCTION OF NEW JINARATHNA SCHOOL, TELWATTA, PERAUYA- GALLE DISTRICT PROJECT FUNDED BY THE KALIAN PEOPLE s>lE)eo <3)?©S§> a>3£ '^eSgjeiliscd oedSsoffi atn^BeJosl 8s> Ob>b> StajQa $s»S tiexofi Bern 100000 India (Kashmir) 1360 6266 Afghanistan 3 Total 88713 >106266 Economic impacts Early estimates of the earthquake damage were put at more than $6.6 billion. Most buildings, roads and bridges in the affected areas were destroyed or severely damaged. Many livestock also perished. The earthquake and its aftershocks triggered many landslides that buried buildings, roads and bridges and even entire villages [4.49]. As these regions are poor, isolated and largely subsistent, the economic impact on the local economy was severe. Learni List the total number of deaths, injuries and homeless people as a result of the earthquake. According to the UN, how many people were directly affected by the earthquake? Why were the economic impacts of the earthquake severe? Describe the environmental impacts of the earthquake. [4.49] The 2005 Kashmir earthquake destroyed local infrastructure Environmental impacts The greatest environmental impact resulting from the earthquake was increased erosion. This resulted from the many landslides triggered by the earthquake and its aftershocks. Snowfall in winter also triggered mudslides on disturbed ground. A future environmental impact of the earthquake will be the clearing of forests to provide timber for new dwellings. CHAPTER4 Plate tectonics: the moving Earth 135 Response to the earthquake The earthquake disaster prompted an urgent response from the two main affected nations and the international community. ■50] Rescuers arching for survivors "the 2005 Kashmir irthquake National The governments of Pakistan and India responded quickly to the disaster, directing their armed forces in search and rescue operations. However, there were many factors that made progress slow and frustrating: o The sheer volume of rubble in collapsed buildings called for the use of heavy machinery that was in short supply. o Roads, bridges and communications were knocked out in many areas, making access to affected areas difficult. o Rescue efforts were hampered by the many aftershocks, which put the lives of the rescuers in danger. o The onset of winter snows further threatened the survivors and made access to many of the affected areas difficult. o Many of the 15 000 villages affected by the earthquake were in remote, inaccessible areas. Relief aid had to be airlifted into these areas. The disputed border of Kashmir between the two nuclear-power neighbours, India and Pakistan, has been a political flashpoint for many years. In an unprecedented act of cooperation, five crossing points on the Line of Control (LoC) between India and Pakistan in the province of Kashmir were opened to allow for the flow of relief supplies and for families to meet their relatives. The people of Pakistan and India responded generously to the disaster relief appeal. In the first few days after the earthquake, the most urgent need of the rescuers was to locate survivors under collapsed buildings before they died of injuries, dehydration and exposure [4.50J. Desperate people used picks and their bare hands in an often futile attempt to find their family and friends. The next priority was to provide water, food, medical supplies, tents and blankets for the survivors. Victims had to be buried as soon as possible in accordance with their religious beliefs. This also helped to prevent any possible outbreak of disease. International Two days after the earthquake, the United Nations warned that more than 2.5 million people were homeless. They urgently needed shelter, especially with winter approaching at these high altitudes. A UN appeal was launched for US$272 million (A$360 million) to aid the earthquake victims. The United States pledged an initial US$50 million (A$66 million). The United States was keen to show support for its political ally Pakistan and flew military aircraft and aid from operational bases in nearby Afghanistan. did you knOW? towards the earthquake ai More than $60 million was donated for the Indian Ocean tsunami victims. [4.51] Many countries sent helicopters to ferry supplies into inaccessible areas. The North Atlantic Treaty Organisation (NATO) airlifted 900 tonnes of aid from warehouses in Turkey. More than 20 countries sent rescue teams. Specially trained rescue dog teams from foreign nations were also used in the rescue operations. After a week, it became apparent that no more survivors would be found and rescuers turned their attention to providing relief for the homeless survivors. Most of the survivors were housed in tent villages. More than ten thousand tents were I flown into the disaster area. The Pakistani Foreign Minister, Khurshid Mahmud Kasuri, told reporters that the international response had been 'overwhelming' and 'transcends' religion and politics. Pakistan even accepted aid from its neighbour and nuclear rival, India. However, when comparisons were made with the international aid for Indian Ocean tsunami victims, a different picture emerges. International response to Asian earthquake a disgrace 9 November 2005 One month on from the Asian earthquake, Save the Children is calling on the international community to dramatically scale up its response. The earthquake has claimed nearly 80000 lives and unless more is done to assist the reported 3.5 million homeless and 79000 injured, thousands more could die from disease and exposure, the charity warns. Executive Director of Save the Children New Zealand John Bowis says: 'Governments have been much slower to release funding than after the tsunami, despite the fact that there are over 50% more people displaced and we are racing against the harsh Himalayan winter. Every day, it is getting colder and people will not survive long in the open or in makeshift shelters. Young children are particularly vulnerable. Our teams on the ground urgently need additional funds now to reach these families before it is too late.' One month on from the devastating earthquake less than a quarter of the US$550 m appealed for by the United Nations has been pledged, and nearly half of this figure (US$60 m) remains undelivered. Save the Children is spending US$6.9 m in the region but this will run out in another month, and thousands more may die unnecessarily unless further funds are secured. The scale of the international response to the UN —r appeal is in stark contrast to that for the tsunami, when international donors pledged over US$700 m for immediate emergency relief in the first two weeks. Number of dead >200000 Number of homeless c. 2 million Initial UN appeai US$977m Pledges to UN appeal, one month on US$775m (79%) Average temperature at night, one month on 22°C and stable 0°C and The earthquake destroyed 70% of the houses in the affected areas and damaged the remainder, leaving up to 3.5 million people in 15000 villages homeless and in need of medical care, water and sanitation support. 'It is a disgrace that the international community has committed such a small proportion of what the UN has asked for—one month later—and with winter closing in,' says Toby Porter, Save the Children UK's Emergencies Director. 'Within days of the quake, the message from the UN was clear. The world needed to provide both an instant and a massive response. The challenges we are facing today were all predicted. The international community should collectively hang its head in shame.' Source: Save the Children New Zealand CHAPTER4 Plate tectonics: the moving Earth 137 [4.52] Pakistani armed forces unload relief supplies from a United States Army helicopter in a remote area of northern Pakistan hit by the earthquake List the main factors that slowed disaster relief reaching those people affected by the 2005 Kashmir earthquake. Describe the types of cooperation that occurred between India and Pakistan immediately after the disaster. Outline the international response to the Kashmir earthquake. According to article [4.51], why was international aid for earthquake victims a 'disgrace'? 1.53] Role of non-government agencies in the earthquake disaster response Non-Government Organizations (NGOs) play a pivotal role in relief, rehabilitation and reconstruction activities United Nations Development Programme—Pakistan, Islamabad, 25 January 2006 As the earthquake hit the northern regions of Pakistan and news started flooding in about the massive devastation that this natural disaster caused on October 8,2005, international, national and local NGOs immediately focused all their efforts to provide aid, relief, and they are now working towards rehabilitation and reconstruction. Although the various agencies of the United Nations, the army and the Government launched a variety of projects for the support of the people of these areas, the main role was and continues to be played by the NGOs. It is through their efforts and partnership that projects are being implemented throughout the earthquake affected areas. 'When we see a smile on the faces of these people, we forget our own hardships and get renewed energy to help these people,' says Shahnawaz Khan, who is working with Sungi Development Foundation (Sungi). 'When we provide someone with a blanket or a heating stove, the prayers we get are so much that we are humbled.' It is through their hard work, that United Nations Development Programme (UNDP) is able to make ► 138 THINKING GEOGRAPHY a difference in the lives of thousands of families. In their partnership with UNDP the work started with the provision of winterized tents and kitchen sets. The main partner in this venture was International Organization for Migration (I0M). These tents were given to families based on a rapid assessment conducted with the help of local NGOs and local authorities. To provide better protection against the extreme cold weather, UNDP launched its transitional shelter project. Islamic Relief, Sungi, the Citizen Foundation, Strengthening Participatory Organization (SPO), National Rural Support Programme, Taraqi Foundation, Human Resource Development Network (HRDN) and Heritage Foundation have partnered with UNDP to provide Corrugated Galvanized Iron (CGI) sheets and tool kits to over 32000 families. Needs assessment were conducted in the snowbound areas of Mansehra, Batagram, Shangla, Kohistan, Muzafarabad, Neelam and Baagh by these agencies in their respective areas. They are now mobilizing the community for the distribution of material for transitional shelters. The organizations also provide support and recycled structure material for the homes. A need was also identified for heating and cooking facilities. Taraqi Foundation and Sungi are the implementing partners for this project. The NGOs oversee the distribution and monitoring of heating stoves and construction of community kitchens and lungars. The NGOS conduct assessments to identify which communities would most benefit from this project and subsequently aid is provided to them. Under this project, the NGO partners also provide the communities with fire safety training. 'Without the support of NGOs and other implementing partners, we would never have been able to provide so much help and so quickly to the people of the northern areas of Pakistan,' says Haoliang Xu, Pakistan UNDP Country Director. The role of NGOs is monumental in the wake of the earthquake and there is no doubt that they have been instrumental in saving thousands of lives. Source: United Nations Development Programme—Pakistan Learning activities According to article [4.53], how important are the NGOs to the disaster relief operation? Describe the work of the United Nations Development Programme in Pakistan. List three types of things that were provided to help the earthquake victims. Role of UN agencies in the earthquake disaster response As with the Indian Ocean tsunami disaster, the role of the UN agencies was to facilitate and coordinate the aid response in collaboration with the government authorities and the NGOs. Reflection on earthquake disaster plans In insurance terms, earthquakes are classified as 'Acts of God' and as such, they are nearly impossible to plan for. Most disaster plans are nearly always reactive rather than proactive. The governments of Pakistan and India responded quickly and enlisted international assistance for the disaster. The disaster plans helped to save many thousands of victims. Was the response appropriate? The response to the earthquake disaster stretched the ability of the international community to respond to disasters of this type. Concerns still exist about the levels of international aid compared with that given to Indian Ocean tsunami victims, but 2005 was a particularly disaster-filled year with the Indian Ocean tsunami, Hurricane Katrina and many smaller disasters. Many nations may have suffered from compassion fatigue. Despite killing fewer people than the tsunami, the Kashmir earthquake presented a greater challenge to aid relief because of the mountainous terrain; winter snows; poor, damaged and non-existent infrastructure; and the logistics of aerial delivery of food, medicines, water and supplies, especially tents and blankets to remote, inaccessible areas. What were the lessons learned? The earthquake caused more than 60 per cent of buildings around Muzaffarabad to collapse. Most of the deaths and injuries in the disaster occurred in collapsed buildings. An assessment by the Pesshawar University of Engineering and Technology showed that about 60 per cent of the buildings were constructed of unreinforced solid concrete masonary blocks. Each block was not tied in with the rest and this made the buildings more prone to earthquake damage. The partial solution to this problem would be to enforce a new building code. However, this would only protect the new buildings and may be difficult to enforce in remote areas in developing nations. In addition, any old buildings would still be as vulnerable to future earthquakes in the earthquake-prone region as those that collapsed in the 2005 earthquake. Update on progress in earthquake-affected regions Many of the mud-brick houses in remote areas affected by the earthquake were destroyed, along with much of livestock the people depend upon. Some 350000 people in remote villages refused to come down to lower altitudes during the winter because they feared for the security of their land and their surviving animals. In early December 2005, another earthquake centered in Afghanistan caused landslides and make travel and communications even more difficult in the earthquake-affected area. More than 200 000 people were housed in makeshift tents, many of which were not properly heated for winter. Sanitation became an issue and there were concerns about disease outbreaks after winter. Some aid workers also criticised the Pakistani government and the UN-led relief operation for not identifying the need for tools and building supplies, especially corrugated iron sheeting. Strategies to address future earthquake threats in the region The United Nations has said that they would like to make earthquake-proof buildings in the region a goal within 10 years. The logistics of getting aid by air to remote, inaccessible regions turned out to be a major problem and a coordinated strategy needs to be developed. The building of helicopter landing pads in remote areas may alleviate this problem somewhat. 140 THINKING GEOGRAPHY Need for new policies to deal with future quakes Just after the Indian Ocean tsunami in December 2004, the United Nations convened a World Conference on Disaster Reduction in Kobe, Hyogo, Japan. The conference discussed progress in disaster risk reduction over the previous decade. Two of the main outcomes were the need for the development of a best practice response to disasters and the implementation of early warning systems to minimise the impacts of disasters. The following aspects of early warning systems for disasters could assist in formulating new policies to address future earthquake disasters in the Kashmir region and indeed around the world: o prior knowledge and assessment of the risks faced by the community o scientific monitoring and warning service for these risks o dissemination of understandable warnings to communities at risk o knowledge, public awareness and preparedness to act. 3a «11 Learning activities What is meant by the term 'compassion fatigue'? How might it relate to the level of aid provided to victims of the Kashmir earthquake? Why did the Kashmir earthquake present a greater challenge to aid relief than the Indian Ocean tsunami? Describe why buildings were so easily damaged in the Kashmir earthquake. Divide the class into small groups. For example, the class might be divided into eight groups with three students in each group. Each group should assume the role of an Asian country represented at the World Conference on Disaster Reduction. The task of each group is to present a strategy plan that reflects the views of the country they represent. The strategy plan presented should address the following areas: • planning for the early warning of natural disasters • response immediately following a natural disaster • support and rebuilding program over the longer term after the event. Your strategy plan should consider responses appropriate to a range of major natural events that impact on humans, for example tsunamis, hurricanes, earthquakes and volcanic eruptions.