Geography - Tectonics

• What is a hazard?


  A potential threat to human life and property
• What are the two types of natural hazards?

  Hydro-meteorological and geophysical
• Where do geophysical hazards occur?

  Near plate boundaries
• What causes earthquakes near the middle of plates?

  Pre-existing weaknesses in the plates
• What is a volcanic hotspot?

  A localized area of high temperature in the lithosphere
• Who first theorized volcanic hotspots?

  Tuzo Wilson in 1963
• What is the Ring of Fire?

  A volcanic hotspot region in the Pacific Ocean
• Where do the most powerful earthquakes usually occur?

  At convergent or conservative boundaries
• What is the Oceanic Fracture Zone (OFZ)?

  A belt of activity through the oceans
• What is the Continental Fracture Zone (CFZ)?

  A belt of activity along mountain ranges
• What trend has been observed in recorded hazards since 1960?

  The total number of recorded hazards has increased
• What has happened to the number of fatalities from hazards since 1960?

  The number of fatalities has decreased
• Why is the total number of people affected by tectonic hazards increasing?

  Due to population growth
• What has significantly increased alongside economic costs of hazards?

  The number of insurance policies
• Why is reporting disaster impacts difficult?

  Due to various factors like location and methods
• What can affect the accuracy of reported deaths in disasters?

  Government bias in reporting numbers
• What are the four sections of the Earth?

  Crust, mantle, outer core, inner core

  
• What is the thickness of oceanic crust?

  7 km thick
• What is the thickness of continental crust?

  Up to 70 km thick
• What is the mantle composed of?

  Silicate rocks rich in iron and magnesium
• What generates convection currents in the mantle?

  A temperature gradient towards the core
• What is the outer core composed of?

  Dense, semi-molten rocks containing iron and nickel
• Why is the inner core solid?

  Due to extreme pressures it experiences
• What causes the core's high temperature?

  Primordial heat and radiogenic heat
• What are the types of plate boundaries and their characteristics?

  • Destructive: Plates move towards each other, causing subduction and forming trenches.
  • Constructive: Plates move away from each other, creating new land through magma.
  • Conservative: Plates slide past each other, causing pressure without creating landforms.

  
• What happens at destructive plate boundaries between continental and oceanic plates?

  Denser oceanic plate subducts below continental plate

  
• What is formed when oceanic and oceanic plates interact at destructive boundaries?

  Ocean trenches and underwater volcanoes

  
• What occurs at continental and continental destructive boundaries?

  Pressure builds, forming fold mountains

  
• What is sea floor spreading?

  New land forms as magma rises and cools
• What evidence supports plate movement and sea floor spreading?

  Paleomagnetism shows magnetic alignment in rocks
• What happens at continental to continental constructive boundaries?

  Rift valleys form as land is forced apart
• What is ridge push?

  Gravity acting on elevated plates pushes them apart
• What is slab pull?

  Subducting plate pulls the rest of the plate with it
• What occurs at conservative plate boundaries?

  Parallel plates move in different directions
• What are the two types of crust?

  Oceanic and continental crust
• What determines whether a plate subducts or is forced upwards?

  The density of the plate
• What is mantle convection?

  Thermal energy causes magma to rise and sink
• What is the primary mechanism for plate movement?

  Slab pull is the primary mechanism
• What happens when plates become stuck at boundaries?

  Pressure builds until plates give way
• What is the focus of an earthquake?

  The point underground where it originates