Earthquakes

• Earthquakes occur when tectonic plates slip past another block along surfaces called faults or fault planes and generate ground shaking.
• The place where the earthquake occurs is the hypocenter or the focus
• The place where it occurs on the Earth’s surface is the epicenter
• Seismic waves are energy released during the slippage along faults.
• Name the two main types of seismic waves

  Body and surface waves
• Body waves travel through Earth's interior
• Surface waves travel through Earth's surface
• Surface waves is the type of seismic waves that do the most damage
• This type of surface wave called primary waves can travel through solid, liquid, and gas
• This type of surface wave called primary waves are the fastest compressional waves
• This type of surface wave called secondary waves can only travel through solid
• The study of earthquakes is called seismology
• The two types of surface waves are love and rayleigh waves
• Rayleigh waves have rolling motion similar to ocean waves
• Love waves have horizontal and vertical shaking in an S-like pattern
• Seismographs/seismometers are used to record the intensity of an earthquake
• Intensity refers to the qualitative measurement of ground shaking
• Magnitude refers to the quantitative measurement of energy released at the earthquake’s source
• Richter Scale is used to measure the magnitude, which measures the amplitude of the largest seismic wave on a seismogram.
• What instruments are used to record the intensity of earthquakes?

  Seismographs or seismometers
• What is used to measure the magnitude of an earthquake?

  Richter scale
• Where do 81% of earthquakes occur?

  Ring of fire
• What are the four types of faults?

  normal, reverse, strike-slip, oblique-slip
• Normal fault: Extension

  Reverse fault: Compression

  Strike-slip fault: Horizontal shearing

  Oblique-slip fault: Horizontal and vertical movement
• Normal fault


  The hanging wall moves DOWN relative to the footwall
• Reverse fault


  The hanging wall moves UP relative to the footwall
• Strike-slip fault


  The sides of the fault move laterally past each other