DRRR W1-5

• Geological Hazards


  Natural phenomena that cause major problems around the world
• Landslides


  • Ground movement on a sloping terrain, aggravated by rain because water is a natural agent of erosion
  • Come in various names such as mudslides, flash floods, avalanches, the actual difference is in their composition
• Types of Landslide


  • Soil Creep Landslide
  • Slumping Landslide
  • Debris Flow Landslide
  • Rock Fall Landslide
• Soil Creep Landslide


  Very slow downslope movement of particles that occurs in every slope covered with loose, weathered material
• Slumping Landslide


  Downward movement of rock debris, usually the consequence of removal of buttressing earth at the foot of a slope of uncosolidated material
• Debris Flow Landslide


  Happens when slope becomes saturated with water which then triggers a landslide of water-soaked mass of rock and soil that slides down the slope
• Rock Fall Landslide


  Sudden slides caused by heavy rain, the rocks on the slope loosens and then slides down the slope
• Sinkhole


  Topographic depression created when ground water dissolves the underlying limestone bedrock, often known as "sink" and "doline"
• Types of Sinkhole


  • Cover Collapse Sinkhole
  • Cover Subsidence Sinkhole
  • Dissolution Sinkhole
  • Artificial Sinkhole
• Cover Collapse Sinkhole


  Develops suddenly (over an hour period) thus, causing catastrophic damage
• Cover Subsidence Sinkhole


  Gradually grows where the sediment covers are permeable and contain sand
• Dissolution Sinkhole


  Occurs in areas where calcareous is exposed on the ground or where thin layers of soil and permeable sand are also covered, limestone or dolomite dissolution is most intense when the water first reaches the rock surface
• Artificial Sinkhole


  Such types of sinks may be caused by various human activities, including groundwater pumping and building
• Causes of Geologic Hazards (Landslides)


  • Climate
  • Earthquakes
  • Weathering
  • Erosion
  • Volcanic Eruption
  • Forest Fires
  • Gravity
  • Mining
  • Clear Cutting
  • Rainfall-Induced Landslides
• Climate


  A general reduction of precipitation leads to a lowering of the water table and a reduction in the overall weight of soil mass
• Weathering


  The natural procedure of rock detoriation that leads to landslide, brought about by the chemical action of water, air, plants and bacteria
• Erosion


  Caused by sporadic running water wiping out latent and lateral slope support enabling landslides to occur easily, continues to shape the planet's landscape today
• Volcanic Eruption


  If an eruption occurs in a wet condition, the soil will start to move downhill instigating a landslide
• Forest Fires


  Burns vegetation that holds soil in place
• Gravity


  Steeper slopes coupled with gravitational force can trigger massive landslides
• Mining


  Vibration emanating from the blasts can weaken soils in other areas susceptible to landslides
• Clear Cutting


  A technique of timber harvesting that eliminates all old trees from the area
• Rainfall-Induced Landslides


  The most common and widespread damaging landslide
• Causes of Geologic Hazards (Sinkhole)


  • Dissolution of Sedimentary Rocks
  • Underground Water Pumpings
• Dissolution of Sedimentary Rocks


  When these rocks are dissolved, it can either form a void of water or air
• Underground Water Pumpings


  Pumping water underneath the ground causes drainage to alter its flow which causes the soil to be eroded by water
• Warning Signs of an Impending Landslide

  • Earlier Landslide as Indicator
  • Tension Cracks
  • Things Moving
  • Water Doing Something Different
• Warning Signs of an Impending Sinkhole

  • Trees or fence posts that tilt or fall
  • Foundations that slant
  • Cracks in the ground
  • Sudden drainage of a pond
  • Sinkholes in the neighborhood
  • New or widening cracks
  • Cracked grout between tiles
  • Cracked tiles
  • Earthly odor in the home after rain
  • Wilted vegetation in a limited area
• Geological Maps


  Shows how geological features, rock units, or geologic strata are shown by colors or symbols to indicate where they are exposed at the surface
• Topography on Maps


  The shapes of the hills and dales are depicted on the map by fine lines that are contours-lines of actual elevation
• Landslide colors


  • Brown (Very high landslide susceptibility)
  • Red (High landslide susceptibility)
  • Green (Moderate landslide susceptibility)
  • Yellow (Low landslide susceptibility)
  • Stripes (Debris flow / Possible accumulation zone)
• Flood colors


  • Dark Blue (Very high flood susceptibility)
  • Dark Purple (High flood susceptibility)
  • Neon Purple (Moderate flood susceptibility)
  • Pastel Purple (Low flood susceptibility)
• Programs That Intensify Nation's Hazard Mitigation Capabilities

  • Protection of Schools and Hospitals
  • Adoption of Nonconstructural Measures
  • Incorporation of Mitigation Into New Development
  • Protection of Culutral Properties
  • Protection of Natural Resources
  • Government Leadership of Mitigation Implementation
  • Mitigation Training
  • Hazard–Specific Research