Geological Hazards: Causes & Signs

• Geological Hazard - extreme natural event in the crust of the earth
• Rainfall-induced Landslide - landslides caused by heavy rain due to storms and southwest moonsoon (habagat)
• Sinkholes - area of ground that has no natural external surface drainage when it rains
• Creep - slow, steady, downward movement of slope
• Slump - both soil and rock, travel short distances (slow to very rapid)
• Rock/debris slide - debris from rockfalls and slumps mix with water
• Rockfall - topples involve rocks (very to extremely rapid; travel great distances)
• Debris flow - It is when the mass (debris avalanche) erodes or follows a channel in the topography
• Mudflow - saturated soils moving at very to extremely rapid velocities
• Driving force - cause the slope to move
• Resisting forces - stabilize the slope and prevent movement
• TYPES OF RAINFALL-INDUCED LANDSLIDES

  • Creep
  • Slump
  • Rock/debris slide
  • Rockfall
  • Debris Flow
  • Mudflow
• Karst terrain - a region where the bedrock (typically limestone or dolomite) can be dissolved by ground water
• Dissolution sinkholes - where flow is focused in preexisting openings in the rocks
• Cover-subsidence sinkholes - it develops gradually where the covering sediments are permeable and contain sand, usually undetected.
• Cover-collapse sinkholes - where the covering sediments contain a significant amount of clay.