Potential Earthquake Hazard

• Ground Shaking or Ground Motion

  ● is used to describe the vibration of the ground

  during an earthquake.
• Ground Shaking or Ground Motion

  It is caused by body waves and surface waves.
• Body and surface waves cause the ground, and

  consequently, a building, to vibrate in a complex

  manner.
• Phivolcs Earthquake Intensity Scale

  White, Gray, Light blue, Light green, yellow, orange yellow, orange, red, dark red
• Body waves determines the epicenter
• P waves (Primary waves)

  • Fastest
  • movement: compression and expansion
• S wave (Secondary Wave)

  • movement: Up & down , Sideways
• Love wave

  • movement: snake like motion
• Rayleigh wave

  • movement: across the earth's surface, up and down
• Ground or Surface Rupture ● is an offset of the ground surface when fault rupture extends to the Earth’s Surface.
• Ground or Surface Rupture

  Caused by normal or reverse (dip-slip)
• Ground or Surface Rupture

  Combination of lateral and vertical offset
• Liquefaction

  ● is a phenomenon in which the strength and

  stiffness of soil is reduced by earthquake shaking

  or other rapid loading.
• Liquefaction

  External stressors loosen the soil particles,

  changing the ground into a less stable base for

  buildings and other structures.
• Liquefaction

  It usually occurs in saturated soils, that is, soils in

  which the space between the individual particles is

  filled with water.
• Earthquake-induced ground subsidence and lateral

  spreading

  Subsidence, or lowering of the ground surface,

  often occurs during earthquakes.
• Subsidence can also occur as ground shaking

  causes loose sediments to “settle” and to lose

  their load-bearing strength or slump down the

  sloping ground.
• Lateral spreading occurs where sloping ground

  starts to move downhill, causing cracks to open up

  that are often seen along hill crests and river

  banks.
• Tsunami

  also known as a seismic sea wave, is a series of

  waves in a water body caused by the displacement

  of a large volume of water generally in an ocean or

  a large lake.
• Unlike normal ocean waves, which are generated

  by wind or tides and by the gravitational pull of the

  Moon and Sun, a tsunami is generated by the

  displacement of water.
• Earthquake-induced ground subsidence and lateral

  spreading

  • Reason why some are fast : sink hole, presence of limestone, acidic water
• Earthquake-induced landslides

  They are an important secondary earthquake

  hazard.