EQ1

• What type of plate boundaries are most common?

  Divergent margins with transform boundaries
• Where can convergent margins be found?

  Between the Pacific Plate and Eurasian plates
• What is a continental collision zone?

  Where the African Plate meets the Eurasian plate
• What are the characteristics of divergent margins?

  • Constructive margins
  • Displayed at ocean ridges
  • Large numbers of shallow focus earthquakes
  • Generally low magnitude, mostly submarine
• What occurs at convergent margins?

  • Actively deforming collisions
  • Plate material melts in the mantle
  • Frequent earthquakes and volcanic eruptions
• What defines conservative margins?

  • Plates slide against each other
  • Horizontal relative movement
  • Classified as sinistral or dextral
  • No lithosphere creation or subduction
  • Sites of shallow focus earthquakes
• What factors determine plate boundaries?

  Motion and plate type
• What are oceanic plates made of?

  High density, basaltic rock
• How thick are oceanic plates?

  7-10 km thick
• How thick are continental plates?

  25-70 km thick
• What are intra-plate earthquakes associated with?

  Re-activated ancient fault lines
• What are hotspot volcanoes?

  • Volcanic eruptions distant from plate boundaries
  • Located at mid-plate hotspots
  • Examples include Hawaii and Galapagos Islands
  • Generated by mantle plumes
• What are mantle plumes?

  Isolated plumes of convecting heat
• How do mantle plumes affect volcanic islands?

  They create chains of volcanic islands
• What is the theory of plate tectonics?

  • Earth's internal structure
  • Mantle convection
  • Palaeomagnetism
  • Sea floor spreading
  • Subduction and slab pull
• How fast do tectonic plates move?

  2-5 cm per year
• What are the two types of tectonic plates?

  Oceanic and continental plates
• What is the asthenosphere?

  A weak, deformable layer beneath the lithosphere
• What is subduction?

  One plate sinking beneath another
• What is slab pull?

  Cold oceanic plate subducting beneath continental plate
• What causes mantle convection?

  • Earth's internal heat engine
  • Radioactive isotopes generate heat
  • Heat flows towards the surface
  • Generates convection currents in the mantle
• What are the layers of the Earth?

  • Crust
  • Mantle (solid but deformable)
  • Outer core (liquid)
  • Inner core (solid)
• What are the characteristics of transform zones?

  • Conservative plate boundaries
  • Join sections of constructive boundaries
  • Zig-zag pattern on Earth's surface
  • Example: San Andreas Fault
• What is the Benioff Zone?

  A zone of earthquakes at subduction zones
• What are the impacts of earthquakes on hazards?

  • Magnitude and type of volcanic eruptions
  • Earthquake magnitude and focal depth
• What are the characteristics of constructive margins?

  • Small, effusive eruptions
  • Shallow earthquakes under 60 km deep
  • Low magnitudes under 5.0
• What occurs at destructive margins?

  • Large earthquakes up to magnitude 9.0
  • Wet partial melting generates explosive magma
  • Thrust faults create shallow, high-magnitude earthquakes
• What are the primary hazards of volcanoes?

  • Lava flows
  • Pyroclastic flows
  • Ash falls
  • Gas eruptions
• What are secondary hazards from volcanoes?

  • Lahars (volcanic mudflows)
  • Jökulhlaups (floods from melting ice)
• What is the speed of lava flow from basaltic eruptions?

  Up to 40 km/h
• What is a pyroclastic flow?

  Dense clouds of hot ash and gas
• What can ash falls cause?

  Killing vegetation and collapsing buildings
• What is a gas eruption?

  Eruption of carbon dioxide and sulphur dioxide
• What are lahars?

  Volcanic mudflows from rainfall on ash
• What are jökulhlaups?

  Floods from volcanoes erupting beneath glaciers
• What are the significant hazards from composite volcanoes?

  • Lava flows
  • Pyroclastic flows
  • Lahars
  • Extensive ash and tephra fall
• How far can volcanic eruptions affect areas?

  • Up to 30 km from the volcanic vent