DRR

• Geologic Hazard


  Adverse geologic condition capable of causing widespread damage or loss of property and life
• Geohazard


  • Geological and environmental conditions involving long-term or short-term geological processes
• Mass Wasting


  The downslope movement of rock, regolith, and soil under the direct influence of gravity
• The controlling force of mass wasting is gravity
• Factors that trigger mass wasting


  • Saturation of material with water
  • Oversteepening of slopes
  • Removal of anchoring vegetation
  • Ground vibration from earthquakes
• Angle of Repose


  The steepest angle at which a material remains stable
• Liquefaction


  A process where water-saturated surface material loses their strength and behave as fluid-like masses that flow
• Types of Mass Wasting Motion


  • Flow
  • Fall
  • Slide
• Earthflow


  A type of mass wasting that leaves a scar on the slope of a hillside and forming a tongue- or teardrop-shaped mass that flows downslope
• Debris Flow


  A relatively rapid type of mass wasting that involves a flow of soil and regolith containing a large amount of water
• Mudflow


  When the material in a debris flow is primarily fine-grained
• Lahar

  Debris flow composed mainly of volcanic material on the flanks of volcanoes
• Talus Slope

  A cone-shaped accumulation of broken rock fragment that fall to the base of the cliff
• Rock Fall


  Quantity/sheets of rock that has fallen freely from a cliff face
• Avalanche


  Rock and debris that hurtle downslope at speeds exceeding 200kph
• Landslide

  Movement of consolidated rocks, debris, and soil due to gravity
• Mudslide


  Movement of mud due to gravity
• Rockslide


  Movement of rocks due to gravity
• Slump


  Downward sliding of a mass of rock or unconsolidated material moving as a unit long a curved surface
• Rapid Mass Wasting Processes


  • Slump
  • Debris Flow
  • Mudflow
  • Lahar
  • Earthflow
  • Landslide
• Rock Slide


  Occur when blocks of bedrock break loose and slide down a slope
• Debris Slide


  If the material in a landslide is largely unconsolidated
• Creep


  A type of mass wasting that is imperceptibly slow
• Solifluction


  A type of mass wasting that is common wherever water cannot escape from the saturated surface layer by infiltrating to deeper levels
• Landslide


  The mass movement of rock, soil, and debris down a slope due to gravity. It occurs when the driving force is greater than the resisting force.
• Landslide Materials


  • Soil
  • Debris
  • Rock
  • Garbage
• Natural Landslide Triggers


  • Intense rainfall
  • Weathering of rocks
  • Ground vibrations created during earthquakes
  • Volcanic activity
• Man-made Landslide Triggers


  • Mining
  • Clear-cutting
• Landslide Triggering Conditions


  • Steep Slopes
  • Weakening of slope material
  • Weathering of rocks
  • Overloading on the slopes
• Signs of Impending Landslide


  • Earlier landslide as indicator
  • Tension cracks
  • Things Moving
  • Water Doing Something Different
• Landslide Mitigation


  Actions taken to prevent or reduce the risk to life, property, social and economic activities, and natural resources from natural hazards
• Landslide Mitigation Measures


  • Awareness
  • Education
  • Preparedness
  • Prediction and warning systems
• Landslide Hazard Map can be used to identify areas at risk of landslides
• Engineering Intervention Measures to Prevent Landslides


  • Benching
  • Retaining Wall
  • Gabion Wall
  • Shotcrete
  • Drainage
  • Erosion Control (Coconet Bio-engineering)
  • Erosion Control (Vetiver Grass)
• Sinkhole


  A topographic depression created when groundwater dissolves the underlying limestone bedrock

  
• The only way to detect if an area is susceptible to sinkhole formation is through core drilling or ground-penetrating radar
• How Sinkholes Occur


  1. Water from rainfall seeps underneath the soil through cracks and fissures

  2. Water erodes the soil and forms a conduit system

  3. If the void is clogged with clay, it forms a depression which then accumulates water and forms a pond

  4. If the void is not clogged, it forms a hole once the cover collapses into the void

  
• Types of Sinkholes


  • Cover Collapse Sinkhole
  • Cover Subsidence Sinkhole
  • Dissolution Sinkhole
  • Artificial Sinkhole
• Signs of Impending Sinkhole


  • Trees or fence posts that tilt or fall
  • Foundations that slant
  • New small ponds that appear after rain
  • Cracks in the ground
  • Sudden drainage of a pond
  • Rapid appearance of a hole in the ground
  • Dips, depressions, slopes that appear in a yard
  • Dead patches of grass or plants
  • Sinkholes in the neighborhood
  • Wilted vegetation in a limited area
  • Well water that is discolored or contaminated with debris
  • Cracking or buckling of home's concrete slab
  • Presence of odd bugs like slugs, centipedes in homes
  • Earthly odor in home after rain
  • New or widening cracks
  • Separation between walls and ceiling or floors
  • Cracks around door and window frames
  • Cracked grout between tiles
  • Cracked tiles
  • Stair step cracks in blocks or bricks
  • Uneven floors, warping of hardwood, bulging or sagging sections
  • Doors or windows that don't open or close easily
  • Cracks in sheetrock near doors or windows