W1

• Landslide

  • aka "landslip"
  • ground movement on a sloping terrain due to gravity
  • it does not happen on flat grounds
  • it can be induced or aggravated by rain
• Water is a natural agent for erosion
• Sinkholes

  • depression or holes in the ground that resulted from the collapse of the surface layer of the soil
  • occurs in areas where soil materials are soft such as limestone, salt beds, or any acidic rocks.
  • can be weakened further by submersion in water
• Karst Landscape is where sinkholes ca be found
• 9 signs of an impending sinkholes:

  1. Unusual wet areas
  2. Soil moving away from the foundation
  3. New cracks or bulges on ground or walls
  4. Broken underground utility lines due to ground tremor
  5. Leaning structures like buildings, walls, poles, and fences
  6. Rapid, silted creek water flow
  7. Changes in groundwater quality or quantity
  8. Leaning or bent signposts or poles
  9. Newly formed ponds or persistend puddles
• Abney Level or Laser rangefinder

  • used to measure the slope angle, soil compaction, and soil strength of an area
  • data is used to determine the level of risk of landslides.
• Ground-Penetrating Radar

  • used to validate sinkholes to provide images of subsurface ground
  • can detect the type of objects, changes in material, and voids and cracks under a layer of soil
  • its measurement can reach up to 15 meters
  • widely used in mapping sinkholes in bohol and cebu