L4: Earthquake Hazards

• EARTHQUAKE

  ● Also known as quake, tremor or temblor.

  ● It is the perceptible shaking of the surface of the Earth, resulting from the sudden release of energy in the Earth’s crust that creates seismic waves.
• POTENTIAL EARTHQUAKE HAZARD

  ● Ground Shaking or Ground Motion

  ● Ground or Surface Rupture

  ○ Surface rupture is an offset of the ground surface when fault rupture

  extends to the Earth’s surface.
• Dip Slip Faulting

  ● Surface ruptures feature vertical offsets
• Strike-Slip Faulting

  ● Produces lateral offsets

  ● Liquefaction

  ○ Is a phenomenon in which the strength and stiffness of a soil is reduced by:

  ■ Earthquake shaking

  ■ Other rapid loading

  ● Induced Ground Substance

  ● Induced Landslides

  ● Tsunami

  ○ Japanese word meaning “harbor waves”

  ○ Occurs when the earthquake is shallow-seated
• What triggers Landslides

  ● Earthquakes and Volcanic Eruptions

  ○ An earthquake loosens the soil and causes cracks on the rocks that will

  eventually fall off.

  ○ The shaking of the ground and rolling of pyroclastic materials during volcanic eruption can cause the land surface to erode and move downward.
• What triggers Landslides

  ● Typhoons

  ○ Rainfall weakens the earth

  ○ If the ground is saturated with water, particularly following heavy rainfall, the

  shaking will result in more landslides than normal.
• Before a landslide or mudslide:

  1. Monitor the signs of an impending landslide.
  2. Monitor the daily weather condition and evacuate as soon as possible if your area is prone to landslides and is experiencing continuous rainfall.
  3. Know the location of your evacuation centers and escape routes
  4. Get involved with the disaster risk management programs of the Barangay Disaster Risk Reduction Committee.
• During a landslide or mudslide:

  When indoors in a landslide area and there is no time to evacuate:

  1. Stay inside and hide under a sturdy and stable object.
• During a landslide or mudslide:

  When caught outdoors:

  1. Stay away from the path of the landslide.
  2. Go to the nearest higher ground away from the landslide.
  3. Run towards the direction of the back of trees or buildings when you see approaching rocks and soil debris.
• After a landslide or mudslide:

  1. Stay away from the landslide area. Secondary landslides and flooding can occur.
  2. Know if there are casualties and report to proper authorities. Initiate rescue operations if capable.
  3. Listen to the radio or watch TV for the latest bulletin about the landslide.
  4. Inspect power and water supply lines for damages and inform proper authorities.
  5. Inspect building foundations and adjacent lots for damages.
• HAZARD MAPS

  ● Are maps that show different hazards that may affect a certain area

  ● For earthquakes:

  ○ Ground-shaking hazard map

  ○ Ground rupture hazard map

  ○ Hazard maps for liquefaction, earthquake-induced landslide and tsunami
• Seismic Hazards

  ● Ground Shaking

  ● Ground Rupture

  ● Ground Failure

  ● Tsunami

  ● Fire
• “The Big One”

  ● An earthquake with a magnitude of no less than 7.2 in the Richter Scale
• Valley Fault System (VFS)

  ● Is an active fault system composed of two fault segments:

  ○ East Valley Fault

  ○ West Valley Fault