Earthquakes

• What is the outer layer of the Earth called?

  The crust
• What are tectonic plates?

  Random shapes that make up the crust
• What are the points where tectonic plates meet called?

  Plate margins or plate boundaries
• Why do earthquakes occur?

  Plates get stuck and release energy
• What is the point in the Earth where an earthquake starts called?

  The focus
• Where is the focus of an earthquake typically located?

  In the mantle
• What is the point directly above the focus on the Earth's surface called?

  The epicenter
• What are seismic waves?

  Vibrations from the earthquake
• How do seismic waves vary in strength?

  Strongest near the epicenter, weakest further away
• How are earthquakes measured?

  Using the moment magnitude scale
• What does a moment magnitude scale rating of 6 indicate?

  Possible slight damage to buildings
• What does a moment magnitude scale rating of 7 or higher indicate?

  Major damage and death
• What is unique about the moment magnitude scale?

  It is logarithmic
• How much larger is a magnitude 7 earthquake compared to a magnitude 6 earthquake?

  10 times bigger
• What are the key components of an earthquake?

  • Focus: point where earthquake starts
  • Epicenter: point directly above focus
  • Seismic waves: vibrations from the earthquake
• What are the implications of the moment magnitude scale ratings?

  • 1 to 6: slight damage possible
  • 7 or higher: major damage and death