Tectonic hazards

Cards (24)

  • how is the earth layered?
    inner core
    outer core
    mantle
    crust
  • what is the plate techtonics theory?
    • suggests that the crust of the earth is split up into seven large plates and a few smaller ones
    • these plates all slowly move around on the earth's surface due to lying on the ductile mantle
  • what is continental drift?
    • all the continents where once joined but they slowly broke up
  • what theories are there to suggest why plates move?
    • convection currents
    • ridge push
    • slab pull
  • how do convection currents cause plates to move?
    • Convection currents are created by heat from within the earth
    • This causes molten rock in the mantle to be heated, so it becomes less dense and rises
    • As it rises further, it cools and sinks back into the core
    • as this occurs, the magma carries the plates with them
  • how does ridge push and slab pull move plates?
    • Occurs at newly formed ocean ridges/constructive plate margines - these are warm ,causing the magma underneath to melt
    • the molten magma rises as plates move apart and it cools to form more plate material
    • As the lithosphere cools, it becomes more dense and slides down, away from the ridge causing
  • Where do volcanos and earthquakes occur?
    • Coincide with tectonic plate margins
    • A lot of volcanos form where the earths crust is very thin - ie hawaii
  • where do earthquakes occur?
    • constructive
    • destructive
    • conservative
  • what is a conservative plate margin
    • Two tectonic plates slide past eachother
    • Friction causes them to get stuck - pressure builds up overtime which causes the friction to be overcome and the plates slip
    • This releases energy in the form of an earthquake which occur very close to the earth's surface
  • Do volcanos form at conservative plate margins

    no
  • what is a destructive plate margin?
    • Forms when an oceanic and continental plate move towards eachother
    • The oceanic crust is heavier so subducts the continental plate
    • This forms an oceanic trench
    • Earthquakes occur when friction is overcome by pressure and energy is released
  • do volcanos form at destructive plate margins?
    Yes
    • Ocean water is drawn down within the sinking oceanic crust, causing it to heat and magma is formed which rises and forms volcanic erruptions
  • what is a constructive plate margin?
    • Two plates move apart from eachother
    • magma from the mantle is forced up, causing the formation of a volcano
    • also may cause an earthquake
  • what are the primary effects of an earthquake
    • people killed and injured
    • buildings and homes destroyed
    • roads, ports and railways destoryed
    • infrastructure such as gas and water pipes are broken
  • what are secondary effects of an earthquake
    • economic growth decreases due to more money being spent on repairign damage
    • emergency services may not be able to access due to lack of travel
  • what can vary the effect of an earthquake?
    • size of earthquake on the richter scale
    • Level of dev - richer cocuntries can predict, prepare and protect more
    • Distance from the epicentre - effects are more severe
    • population density - could lead to mroe deaths if there mroe people livign in one area
    • time of day - are people all at home, at work, commuting etc
  • what are the primary effects of a volcano?
    • farmland and property destoryed
    • people and animals killed
    • contaminated water supplies
    • air travel restricted or cancelled due to ash
    • air quality
  • secondary effects of a volcano
    • Rainfall mix with ash to form mudflows
    • ash provides fertile soil
  • immediate responses to tectonic hazards?
    • issue warnings about activity that may follow ie risk of aftershocks
    • rescue team sent out for survivors
    • provide immidiate treatment for injured
    • food, drink and shelter provided for those who's homes have been destroyed
    • recover and identify bodies
  • long term effects of earthquakes
    • rebuilding and reparing properties and infrastructure
    • improve building regulations
    • develop opportuntities for economy to recover
  • why do people live next to volcanos if they have many dangers?
    • Geothermal enery can be derived from steam underground which can drive turbines
    • Tourism - volcanos attract visitors which creates a lot of job opportunities
    • Mining - Lava contains valuable minerals such as gold, silver, diamonds, copper etc
    • Agriculture - volcanic areas contain rich nutrient soil which helps crops thrive
  • Why do people live next to tectonic hazards?
    • Cannot afford to move away
    • Most areas are safe for long periods of time and a disastor is rare
    • residents dont want to leave culture and home
  • How can risks of volcanic erruptions be reduced?
    MONITOR - satellites can be used to detect surface shape changes of a volcano. Gas levels can be monitored. Surface temperature can be monitered and will get hotter when magma is rising to the surface
    PREDICTION - Tectonic plate movement can be monitored and time since the last erruption may show patterns to predict when the next one will happen - this will alow people to evacuate
    PROTECTION - evacuate all residents in an area where lava and air quality is harmful
    PLANNING - evacuation plan, have emergency supplies and shelter planned, educate local people on actions they can take to reduce the loss of life
  • how can risks of earthquakes be reduced?
    MONITORING + PREDICTION - earthquakes occur along plate margins so the general locations can be predicted. Technology can be used to try to monitor time, date and magnitude. Seismometers can measure foreshocks. Locations are mapped to look for patterns to predict where the next one may occur
    PROTECTION - HICs are able to contruct suitable buildings which can withstand earthquakes
    PLANNING - planningn and