DRRR

• Earthquake


  The perceptible shaking of the surface of the Earth, resulting from sudden release of energy in the Earth's crust that creates seismic waves

  
• Earth


  • The outermost layer is broken into pieces called 'plates' which are in continuous motion
  • Plates move because of intense heat in the Earth's core that causes molten rock in the mantle layer to move in a convection cell pattern
• Seafloor spreading


  Hot magma rises to the surface at spreading ridges and forms new crust, pushing the rest of the plate out of its way
• Types of Natural Earthquakes

  • Tectonic
  • Volcanic
• Tectonic earthquake


  Produced by sudden movement along faults and plate boundaries
• Volcanic earthquake


  Produced by movement of magma beneath volcanoes
• Earthquake Hazards


  • Ground shaking or Ground motion
  • Ground surface rupture
  • Liquefication
  • Tsunami
  • Earthquake induced landslide
• Ground shaking


  The disruptive up and down and sideways motion experienced during an earthquake

  
• Most natural earthquakes are caused by sudden slip along fault zones
• Fault


  A fracture on which one body of rock slides past another
• Types of Faults


  • Normal fault
  • Reverse fault
  • Left-lateral strike-slip fault
  • Right-lateral strike-slip fault
• How Seismic Movement Produce Earthquake Waves


  1. Primary waves (P waves)

  2. Secondary waves (S waves)

  3. Surface waves

  
• Primary waves (P waves)


  The fastest seismic waves, can travel through solids, liquids, and gases
• Secondary waves (S waves)


  Travel through Earth's interior at about half the speed of primary waves, can travel through rock but not liquids or gases
• Surface waves


  Seismic waves that move along Earth's surface, cause the largest ground movements and the most damage
• How Ground Shaking is Measured


  • Velocity
  • Acceleration
  • Frequency content of shaking
  • Duration (How long the shaking continues)
• Vibration Hazard Zoning Activity

  Identify the areas that are shaken more intensely using knowledge of the types of rock and their relevant ground-shaking characteristics
• Ground rupture


  The creation of new or the renewed movement of old fractures, oftentimes with two blocks on both side moving in opposite direction
• Liquefaction


  Loosely packed/water-logged sediments at/or near the ground surface lose their strength in response to strong ground shaking
• How Liquefaction Occurs


  Vibration rearranges sand particles into a more compact state, increasing pore pressure and causing sediments to become mobile and attain a jelly-like consistency

  The shaking caused by the passing of seismic waves, mainly shear or S-wave
• Types of Liquefaction Features


  • Flow failure
  • Lateral spread
  • Ground oscillation
  • Loss of bearing strength
• Tsunami


  Waves that travel 20-30 miles per hour with heights of 10-100 feet, causing flooding and disrupting transportation, power, communications, and the water supply
• Earthquake


  The perceptible shaking of the surface of the Earth, resulting from sudden release of energy in the Earth's crust that creates seismic waves

  
• Earth


  • The outermost layer is broken into pieces called 'plates' which are in continuous motion
  • Plates move because of intense heat in the Earth's core that causes molten rock in the mantle layer to move in a convection cell pattern
• Seafloor spreading


  Hot magma rises to the surface at spreading ridges and forms new crust, pushing the rest of the plate out of its way
• Types of Natural Earthquakes


  • Tectonic
  • Volcanic
• Tectonic earthquake


  Produced by sudden movement along faults and plate boundaries
• Volcanic earthquake


  Produced by movement of magma beneath volcanoes
• Earthquake Hazards


  • Ground shaking or Ground motion
  • Ground surface rupture
  • Liquefication
  • Tsunami
  • Earthquake induced landslide
• Ground shaking


  The disruptive up and down and sideways motion experienced during an earthquake

  
• Most natural earthquakes are caused by sudden slip along fault zones
• Fault


  A fracture on which one body of rock slides past another
• Types of Faults


  • Normal fault
  • Reverse fault
  • Left-lateral strike-slip fault
  • Right-lateral strike-slip fault
• How Seismic Movement Produce Earthquake Waves


  1. Primary waves (P waves)

  2. Secondary waves (S waves)

  3. Surface waves

  
• Primary waves (P waves)


  The fastest seismic waves, can travel through solids, liquids, and gases
• Secondary waves (S waves)


  Travel through Earth's interior at about half the speed of primary waves, can travel through rock but not liquids or gases
• Surface waves


  Seismic waves that move along Earth's surface, cause the largest ground movements and the most damage
• How Ground Shaking is Measured


  • Velocity
  • Acceleration
  • Frequency content of shaking
  • Duration (How long the shaking continues)
• Vibration Hazard Zoning Activity


  Identify the areas that are shaken more intensely using knowledge of the types of rock and their relevant ground-shaking characteristics
• Ground rupture


  The creation of new or the renewed movement of old fractures, oftentimes with two blocks on both side moving in opposite direction