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Tectonic hazards - Coggle Diagram

- - - - Convectional current
        
        The movement of heat within the mantle. Material in the mantle is heated by the core, causing the mantle material to expand, rise and spread out beneath the plates
        
        The plates are dragged along and move away from each other during the process
- - - - Inner core has a radius of 1,400 kilometres and a solid layer
        
        Due to extreme pressure exerted on it by the surrounding layers
      - Outer core has a radius of 2,100 kilometres and a liquid layer
  - - - Upper mantle
      - Lower mantle
    - - Found along the overlying crust
        
        Litmosphere
        
        Float along the softer asthenosphere
        
        High temperature and pressure to bring rocks close enough to their melting point for them to be easily deformed
        
        Rigid and brittle
- - - - Formed when two continental plates diverge causing them to stretch causing fractures to form at the plate boundary
        
        The land between the two continental plates sink, forming a linear depression known as a rift valley
      - East African Rift Valley
        
        The Nubian boundary of the African plate moving away from the Somalian boundary of the African plate
        
        African plates ( Somalian and Nubian)
    - - Magma moves upwards to the surface where it cools to form new oceanic crust along these boundaries
      - Found in both oceanic-oceanic plate boundaries and continental-continental plate boundaries
    - - Oceanic-oceanic plates, magma rise from the mantle to form a new seafloor between the plates as they move apart
        
        Occurs when lava flows out onto the seafloor where it will cool down and solidifies. This forms a mid-oceanic ridge, which is the central ridge structure that divides the ocean basin in half
        
        The newly formed rocks are closest to the mid-oceanic ridge and are therefore younger than those further away
      - Volcanic islands in the North Atlantic Ocean
        
        When two oceanic plate diverge, fractures are formed at the plate boundary
        
        Magma rise at the zone of divergence to create a ridge of new ocean floor known as a mid-oceanic ridge
        
        Magma builds up and solidifies to form undersea volcanoes
        
        When these volcanoes eventually grow above sea level, they are known as volcanic islands
        
        North American plate and Eurasian plate
  - - - The denser plates subduct under the other less dense plate
        
        Subduction zone formed
        
        A depression in the sea floor called an oceanic trench is created
        
        Denser subducting plate causes the mantle material above it to melt, forming magma
        
        Magma rises through the crust to form volcanoes
      - Mariana Trench and Mariana island
        
        Denser oceanic plate will subduct beneath the less dense oceanic plate
        
        Deep oceanic trench is formed at the point of subduction
        
        Subducted oceanic plate causes the mantle material above it to melt, forming magma
        
        Magma rises through the crust and forms volcanoes. Eventually, a chain of arc islands is formed
        
        Earthquakes may occur at the boundary between two plates. This is due to the friction created between the moving rock masses when a plate subducts under another
        
        Pacific plate and Philippine plate
    - - Plate resist subduction as both plates are too thick and buoyant for subduction to occur
        
        Causes plates to break and slide along fractures in the crust
        
        Layers of rock on the upper part of the crust are then compressed together , they fold upwards or sideways, creating fold mountains
      - Himalayan mountain
        
        Crust are compressed and cause massive folds
        
        Form mountains
        
        Indian plate and Eurasian plate
  - - - Movement results in the formation of transform fault
        
        Tremendous stress builds up and is eventually released in the form of earthquakes
    - - 700 km of North American Plate to move an average 2.5 m, at almost 7 m, in less than 1 min
- - - - Benefits
        
        Geothermal energy
        
        Derived from the heat from the heat in the earth's crust
        
        Ground water comes into contact with hot rocks beneath the surface, it heats up and erupts as hot water
        
        The hot water or steam can be harnessed to drive turbines and produce electricity
        
        Iceland
        
        Most of the electricity is generated from geothermal power because of the large number of volcanoes in the country
        
        Tourism
        
        Offers a wide range of activities for tourists to engage in
        
        Examples:
        
        Pompeii, Italy
        
        Ruins of a Roman town was buried by layers of ash from the nearby Mount Vesuvius when it erupted in 79 CE
        
        Precious stones and minerals
        
        Examples:
        
        Kimberly, South Africa
        
        Volcanic rocks rich in diamonds
        
        Volcanic rocks rich in precious stones and minerals
        
        Resources extracted from volcanic areas after millions of years
        
        Fertile soil
        
        Lava and ash from volcanic eruptions break down to form fertile volcanic soils
        
        Examples:
        
        Volcanic soils in Java and Bali supports the cultivation of rice, tea and coffee
        
        Rocks rich in minerals
        
        Best for agriculture
      - Risk
        
        Pollution
        
        Ash particles ejected during a volcanic eruption
        
        Block sunlight, suffocate crops, respiratory problems in humans and animals
        
        A release in harmful gases like carbon dioxide, sulfur dioxide m hydrogen and carbon monoxide
        
        Massive destruction by volcanic materials
        
        Example:
        
        Kilauea, Hawaii
        
        Volcanic bombs of heated rocks fall in areas surrounding the volcano causing damage
        
        Low silica lava moving rapidly and flows over long distances
        
        Causing damage to larger areas
        
        Ejection of materials of lava and pyroclasts
        
        Results in the damage of property
        
        Pyroclast consist of ash, rock fragments and volcanic bombs
    - - Stratovolcano
        
        Examples:
        
        Mount Mayon, Philippines
        
        Characteristics
        
        Secondary cones may develop as magma from the vent seeps into the sides of the cone and erupts
        
        High silica lava
        
        Explosive lava
        
        Traps gases more easily
        
        Build up of pressure below the earth's surface
        
        Steep top and gentle at the base
      - Shield volcano
        
        Examples:
        
        Mount Washington, United States of America
        
        Characteristics
        
        Base of the volcano increases in size as lava accumulates
        
        Low silica lava
        
        Flows out easily and spreads out over a large area before solidifying
        
        Less explosive lava
        
        Traps less gas
        
        Broad summits and gently sloping sides
    - - At the areas where plates converge or diverge, magma accumulates in the magma chambers. As the pressure builds up, magma will find its way to the surface of the earth through vents
        
        Over many years, lava, ash and rock fragment will continue to build up the volcano and it grow in height and size
        
        Sometimes the crater might be blocked, leading to an explosive eruption that results in a large depression, called caldera
  - - - Due to convergence movement enacted on plates, compressional force occurs
        
        Leads to faults appearing in the crust known as faulting
        
        With the compressional force and presence of faults, the central section of the crust will sink
        
        Overtime the central rising section would form the rift valley, and the higher section and block mountains
    - - Divergence enacted on the plates , tensional force occurs
        
        Leads to faults appearing in the crust known as faulting
        
        With the tensional force and presence of faults, the central section of the crust will sink
        
        Overtime the central sinking section would form the rift valley, and the higher section and block mountains
  - - - As the continental crust cannot subduct, the compressional force causes the continental layers to buckle
        
        A process known as folding
        
        In a folded rock layer, the upfold is called anticline and the downfold is known as the syncline
        
        Overtime, the anticline and the sycline would become more prominent
- - - - A set of rules implemented to restrict developments in certain areas
      - Examples:
        
        California, United States of America
        
        All new building developments are not built across fault lines or areas at risk of liquefaction
        
        Liquefaction occurs when vibration from earthquakes causes saturated soil to flow in the form of a liquid
        
        Ground becomes unstable and buildings should not be constructed in these areas as it is unsafe
      - Prohibition of constructing new buildings in low lying land which are vulnerable to tsunamis
        
        Developments may not be allowed only when protective barriers such as seawalls facing the ocean are constructed
        
        Examples:
        
        Coasts of Japan and North America
      - Ineffectiveness
        
        Policy has to be carried out on already built land and private owners
        
        Government authorities had to buy land from private owners
        
        Trying to compensate those who have to move and put into place effective protection measures
        
        Owners are reluctant to move as they believe that another hazard would not happen
        
        Costly
    - - Developed advanced engineering to withstand the vibration associated with an earthquake
        
        Effective building designs can reduce the collapse of buildings and minimise the damage caused by an earthquake
        
        Roads, bridges and dams can be built to resist the shaking of the ground so that they do not collapse, or
        
        Homes, office buildings and factories can be fitted with trip switches that ensure all electrical points are switched off in the event of an earthquake
        
        Examples:
        
        Japan
        
        Machines in factories automatically shut down when they sense an earthquake
      - Examples:
        
        Taipei 101
        
        Steel and reinforced concrete
        
        To withstand earthquakes better than brittle materials
        
        Damping device
        
        Act as shock absorbers for some of the seismic energy released during an earthquake
        
        Acts also as counterweights which move in the direction opposite to the motion of an earthquake
        
        Prevents the building from swaying too much and collapsing
        
        Constructing materials
        
        Buildings with a wide and heavy base decreases the likelihood of these buildings collapsing
        
        Reinforced by heavy metal bars
        
        Base isolation bearings
        
        Placed between the ground and the building
        
        Prevents the building from shaking too much during an earthquake
        
        Isolation bearings absorb the force of an earthquake and reduces the movement of the building
      - Ineffectiveness
        
        Adds up to the cost of construction an maintenance of buildings
      - Effectiveness
        
        Reduced lives lost
        
        Faster rescue
        
        Faster evacuations
        
        Less money spent on recovery for the affected areas
    - - Form of preparedness measure where people practise the steps to take when an earthquake occurs
        
        Creates awareness among the population and reduces levels of panic and irrational behaviour during an event
      - Examples:
        
        Japan
        
        Commemoration of Disaster Prevention Day on 1st of September since 1960
        
        Simulation of the magnitude of an earthquake
        
        Main roads are blocked to create the possible road conditions in the event of an earthquake
        
        Aims to prepare people in an event of a disaster
      - Effectiveness
        
        Creates awareness among the population and reduces levels of panic and irrational behaviour during an event
      - Ineffectiveness:
        
        Designed based on the most serious earthquake ever recorded
        
        2011
        
        Japan experienced an earthquake on a scale never experienced before
        
        Emergency drills and evacuation plans were inadequate to prevent the devastation of the areas affected by the earthquake
        
        Drills were only effective if there was enough time for people to evacuate
    - - Earthquakes can be monitored by studying the history of when and where earthquakes have occurred
        
        Provides an estimation of the frequency and magnitude of earthquakes at particular fault lines
      - Seismic risks maps
        
        Shows the likelihood of locations at risk from earthquake movements or liquefaction are produced from such studies
        
        Ineffectiveness
        
        Do not provide precise information about the time, location and magnitude of future earthquakes
      - Earthquake sensors
        
        Helps to monitor the frequency of vibrations and detect possible developments of an earthquake
        
        Gathered from hundreds of observation stations installed on bridges and roads in Japan
        
        Enable occurence of an earthquake can be predicted
        
        Estimate the damage to bridges, railways or other infastructure
      - Effectiveness
        
        Expensive to obtain, install and use
        
        Occurs seconds when a warning is sounded
        
        Insufficient time for evacuation
        
        Noise, lightning or device failure may interfere with the seismograph and could result in false warnings being given
        
        Difficult to guve accurate warnings when multiple earthquakes occur close to each other
    - - Helps to predict tsunamis
        
        Linked to warning systems which are activated to warn people about the occurence of a tsunami
      - Surface buoy
        
        Connected to a pressure sensor anchored to the sea floor
        
        Temperature and pressure are measured and relayed to the buoy every 15 seconds
        
        Information is sent via satallite to land-based tsunami warning stations for analysis
      - Ineffectiveness
        
        False alarms when the waves are high
        
        Little time to evacuate once an approaching tsunami is detected
  - - - Implementation
        
        People are trapped under collapsed buildings are quickly located and freed
      - Effectiveness
        
        Some survivors are found after being trapped for a couple of week without food and water
        
        Examples:
        
        Tohoku, Japan
        
        Sniffer dogs and heat sensors where deployed and successfully rescued many people who were trapped
      - Ineffectiveness
        
        Rescue workers have a limited time of 72 hours, or three days, to find trapped survivors
        
        Without food, water and treatement, trapped survivors may not survive in three days
        
        Examples:
        
        Tohoku, Japan
        
        Workers have a limited time of three days to search and rescue survivors in two towns
    - - Implementation
        
        The injured are treated and provides with clean water
        
        Prevents dehydration and spread of diseases
      - Effectiveness
        
        A provision of immediate aid helps surviours continue with their lives
        
        Examples:
        
        2002
        
        Afyon
        
        Turkish Red Crescent Society
        
        Delieverying resources to the affected regions
        
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      - Ineffectiveness
        
        Medical supplies, food and water may not be sufficient and this may cause social unrest
        
        Examples:
        
        2010
        
        Haiti
        
        Looting and fighting broke out as people fought over resources
  - - - Implementation
        
        Infastructure and amenities are rebuilt and improve upon a disaster
      - Effectiveness
        
        Authorities can implement stricter building codes to ensure infastructure
        
        Examples:
        
        1995
        
        Kobe, Japan
        
        Japan spents billions developing technology to build more earthquake-resistant buildings
      - Ineffectiveness
        
        Reinforced buildings that are not neccesarily protected against tsunamis
        
        Examples:
        
        2010
        
        Chile, United States of America
        
        Buildings were well protected against earthquakes
        
        However, the coastal areas were greatly damaged from a tsunami when an earthquake struck
    - - Implementation
        
        Health options like long-term counselling are provided
        
        The loss of a loved one, friend and a job from an earthquake can cause trauma
      - Effectiveness
        
        Problems can be indentified and addressed early
        
        2011
        
        Christchruch, New Zealand
        
        Survivors were facing problems of anciety and depression were identifed amongst all age groups
        
        Greater number of healh workers deployed
      - Ineffectiveness
        
        Improving health options, such as restoring resilience of people after an earthqiale , can be very challenging
        
        2010
        
        Haiti
        
        Many surviours continue to lack access to basic necessities
- - - - Tsunamis
        
        The movement of the sea floor during a large earthquake at the subduction zone
        
        An explosive underwater volcanic eruption
        
        Due to earthquakes or volcanic eruptions
        
        A landslide above seal level which causes materials to plunge into the water
        
        Seismic energy from offshore forces out a mass of sea water
        
        Tsunami waves start at a height of less than 1 m, with wave lengths of 100 to 150 Km, at a speed of 800 km/h and may pass undetected
        
        On reaching shallower water, greater friction slows the waves and forces them to increase in heights of 15 m
        
        Sometimes, the sea recedes from the coast before advancing onshore. If the sea recedes, it only does so minutes before the tsunami reaches the shore. The sea recedes because water first rushes to fill the void caused by the movement of the sea floor. Water is then forced out again soon afterwards, resulting in a tsunami
        
        Examples:
        
        2004
        
        9.2 magnitude earthquake occurred in the Indian Ocean and triggered a tsunami with waves that spread throughout the Indian Ocean
        
        Damage in to coastal communities in 12 countries
        
        Especially low-lying coastal areas of western Sumatra, Indonesia
      - Disruption of services
        
        Earthquakes disrupting services like, electricity, gas and water which could affect a large area
        
        Vibration on the ground can snap pipes and break cables which may cause the outbreak of fire
        
        Examples:
        
        1995
        
        Kobe, Japan
        
        Earthquake that struck damaged pipes and transmission lines. This disrupted electricity, gas and water supplies to about a million of Kobe city's 1.4 million residents
      - Landslides
        
        Shaking of the ground during an earthquake can weaken the slopes of hills and mountains
        
        Landslides are rapid downslope movements of soil, rock and vegetation debris from a slope
        
        Examples:
        
        1970
        
        Mount Peru
        
        Destabilised the slopes of Mount Huscaran and triggered a massive landslide
        
        Death toll more than 18,000 and only 200 people survived
      - Destruction to properties
        
        Earthquakes causing widespread destruction
        
        People are left homeless after the disaster
        
        Examples:
        
        2011
        
        Tohoku, Japan
        
        Earthquake caused tsunami which travelled up to 10 km inland
        
        Extensive structural damage resulted in hundreds of thousands of people being forced out of their homes
      - Destruction of infastructure
        
        Earthquakes causing cracks to form in infrastructure such as roads and bridges
        
        Disruption of transportation
        
        Examples:
        
        1995
        
        Kobe, Japan
        
        After an earthquake, places in the city became inaccessible or difficult to reach
        
        A cost in repair of US$300 billion
      - Loss of lives
        
        Earthquakes and their associated hazards often threaten the lives of those living in earthquake zones
        
        Examples:
        
        2011
        
        Tohoku, Japan
        
        Earthquake caused a death toll of 28,000 people
    - - Plates moving along plate boundaries
        
        Friction between moving plates causes the slow build-up of stress on the rocks found on either side of the fault
        
        Rocks are unable to withstand the increasing stress, this is where there is a sudden slip many metres, causing an earthquakes
      - Energy released in the form of seismic waves
        
        Waves radiate out from a point of sudden energy release
        
        Known as focus
        
        The point on the earth's surface directly above the focus is the epicentre
        
        Most of the energy released by an earthquake travels along the surface of the earth, causing the ground to vibrate violently