Earthquakes & Volcanoes

• Movement caused by earthquakes


  Plate movement, stress buildup, and fault movement
• Where do volcanoes and earthquakes occur?

  Where plates meet
• What happens at destructive plate margins?

  • Denser oceanic plate moves down into the mantle
  • Melts and forms magma
  • Magma rises through vents to form a volcano
• How do volcanoes form at constructive plate margins?

  • Magma rises into the gap created by moving apart plates
  • Forms a volcano
• What are hotspots in relation to volcanoes?

  Areas in the mantle that are really hot
• What do volcanoes emit when they erupt?

  Lava and gas
• What can ash emitted by volcanoes cause?

  Cover land, block out the sun
• What are pyroclastic flows?

  Super heated currents of gas, ash, and rock
• How do earthquakes occur at different plate margins?

  • Destructive margins: pressure builds as one plate is forced down
  • Constructive margins: tension builds as plates move apart
  • Conservative margins: tension builds when plates grind past each other
• What happens when plates jerk past one another?

  They send out shock waves
• What is the focus of an earthquake?

  The point where the earthquake starts
• What is the epicenter of an earthquake?

  The point on the surface above the focus
• How are earthquakes measured?

  Using the moment magnitude scale
• What does the moment magnitude scale measure?

  • Measures the amount of energy released
  • Indicates the magnitude of the earthquake
• What is significant about the logarithmic scale of the moment magnitude scale?

  A magnitude 7 causes ten times more shaking than 6
• What damage do earthquakes of magnitude 6 and below typically cause?

  Slight damage to buildings
• What can earthquakes of magnitude 7 and above cause?

  Major damage and deaths
• What should you know about tectonic hazards?

  • Know how and where they form
  • No need to draw maps
• What are the three types of plate margins?

  • Destructive margins
  • Constructive margins
  • Conservative margins
• What is the role of pressure in earthquakes?

  Pressure builds up at plate margins
• How does the moment magnitude scale differ from the Richter scale?

  Moment magnitude measures energy, Richter does not