LESSON 3

• Landslide

  Rock, dirt, or debris falling down a sloping section of land

  
• Sinkhole


  A depression or hole caused by the collapse of the surface layer of the ground
• GEOLOGICAL HAZARD
• Hazards that are associated with earth materials such as toxic materials or earth processes which include landslides, earthquakes, sinkholes, and many more
• These hazards may cause injury, disability, loss of home, loss of income, and even loss of loved ones
• Landslide


  • Caused by storms, earthquakes, volcanoes or other factors which makes the slope unstable

  
• Major causes of landslides


  • Geology (weakened or stiffened soil/rock layers)
  • Morphology (loss of vegetation, heavy water)
  • Human activity (deforestation, construction)

  
• Rainfall-induced landslide


  Occur due to prolonged or heavy rainfall, increasing the weight of the land mass

  
• The development of a rainfall-induced landslide may take several days but the landslide itself will only take a few minutes to cause a disaster

  
• Rainfall-induced landslides can form debris flows when they mix with additional water and sediments from their path

  
• Rainfall-induced landslides may sweep away a whole community in an instant

  
• Warning signs of an impending landslide


  • Bulging ground at base of slope
  • Water breaking through ground
  • Water at base of slope
  • Tilting fences/walls/trees
  • Cracks in slope
  • Broken water pipes
  • Cracks in buildings
  • Stuck doors/windows
  • Widening cracks in ground
  • Land movements and debris downslope
  • Walls/stairs pulling away from building
  • Unusual noises
  • Rapid rise in water levels

  
• The Early Warning System (EWS) of the PHIVOLCS and PAGASA are monitoring systems designed to forecasts events accompanying landslides in order to provide a warning about hazards

  
• Water is the primary cause of most sinkholes


  It dissolves soluble rocks such as limestone, dolomite, and gypsum
• Types of sinkholes


  • Solution sinkholes
  • Cover subsidence sinkholes
  • Cover collapse sinkholes
• Impending signs of a sinkhole


  • New cracks in buildings
  • Cracks in the area
  • Depression at ground level
  • Rapid appearance of a crater
• Geological hazard maps are used to anticipate hazards from geological events and educate the public
• Mitigation strategies for rainfall-induced landslides include studying rainfall patterns, soil type, land characteristics, and nearby water bodies

  
• What to do BEFORE a rainfall-induced landslide


  • Have an emergency plan
  • Find out if you live in a high-risk area
  • Listen to weather reports
  • Talk with family/neighbors
  • Familiarize with the land
  • Have emergency contacts and kit

  
• What to do DURING a rainfall-induced landslide

  • Listen to news for warnings
  • Be alert for unusual sounds
  • Move away from the path quickly
  • Be vigilant for changes in water flow

  
• What to do AFTER a rainfall-induced landslide


  • Go to an evacuation center
  • Stay away from the slide area
  • Listen to local news
  • Report damage
  • Check building and land for damage
  • Seek advice from experts

  
• Mitigation strategies for sinkholes include ground surveys and checking for signs of impending disaster
• What to do BEFORE a sinkhole


  • Check for cracks, exposed items, ground patterns, water accumulation, slumping structures, and interrupted utilities
• What to do DURING a sinkhole


  • Don't get close, call authorities if large, keep children away, secure small holes, document with photos
• What to do AFTER a sinkhole

  • Don't refill with trash, prevent construction, call authorities to mitigate
• Homework 1: What do you think will happen in the area of Mahinog in case there is torrential storms?
• Homework 2: Is Guinsiliban's susceptibility to landslide low? Why?
• Homework 3: If there would be a landslide to happen in every area with high susceptibility on the Camiguin circumferential road, what do you think will happen in terms of search and retrieval operations? Why?