module 1

• Geological Hazards


  Gradual or sudden natural earth processes that can cause injury, loss of life, property damage, loss of livelihood and services, social or economic disruption, environmental changes
• Landslide


  • Rock, dirt or debris falling down a sloping section of land
  • Caused by storms, earthquakes, volcanoes or other factors which makes the slope unstable
• Major causes of landslide

  • Geology - material of the soil or rock area or layers of earth has weakened or stiffened in some part
  • Morphology - structure of the land, soil or rock weakened due to loss of vegetation or root system, prolonged rainfall or heavy water leakage
  • Human activity - agriculture, construction, deforestation, excavation weakens the integrity of the earth
• Rainfall-Induced Landslides


  1. Prolonged or heavy rainfall increases the weight of the landmass

  2. Landslide can form debris flows as it mixes with additional water and sediments from its path
• Signs of Rainfall-Induced Landslides


  • Unusual noises like breaking trees or knocking boulders
  • Slight rumbling sound that rises in amplitude
  • Rapid rise in water level of the creeks, likely followed by increased turbidity
• Rainfall-Induced Landslides


  • Solid waste landslide at Barangay Payatas, Quezon City, Metro Manila, July 2000
  • Rain-induced landslide in Panaon Island, southern Leyte, December
• Sinkhole


  • Depression or hole caused by the collapse of the surface layer of the ground
  • Water is the primary cause as it dissolves water-soluble rocks like limestone, dolomite and gypsum
• Kinds of Sinkholes


  • Natural sinkholes - caused by physical and chemical erosion
  • Man-made sinkholes - caused by drilling, mining, road construction, broken water pipes
• Types of Sinkholes


  • Solution sinkholes - common in areas with thin soil cover, bedrock erodes and particles collect forming a depression
  • Cover Subsidence sinkholes - bedrock covered by soil and materials not well-knitted together, soil enters cracks as bedrock erodes
  • Cover Collapse sinkholes - bedrock covered by deep soil, crack forms as bedrock erodes leading to sudden collapse
• Impending Signs of Sinkholes

  • New cracks at the foundation of buildings and houses
  • Cracks in an area
  • Depressions at ground level
  • Rapid appearance of a crater in the ground
• Geology 


  material of the soil or rock area or layers of earth has weakened or stiffened in some part
• Morphology


  - structure of the land, soil or rock weakened due to loss of vegetation or root system, prolonged rainfall or heavy water leakage