Disaster Risk and Reduction

• Geological hazards - are natural phenomena that cause major problems around the world.
• Landslide - a ground movement on a sloping terrain. It does not happen on flat ground because of the angle on the ground, gravity induces the land to move downward.
• Landslide is aggravated by rain because water is a natural agent for erosion.
• Structures that are built on steep-slope mountains have a high vulnerability to landslide hazards especially during heavy rains.
• Types of Landslides:

  • Soil Creep Landslide
  • Slumping Landslide
  • Debris Flow Landslide
  • Rock Fall landslides
• Soil Creep Landslide - is a very slow downslope movement of particles that occurs in every slope covered with loose, weathered material
• Slumping Landslide - is a downward movement of rock debris, usually the consequence of removal of buttressing earth at the foot of a slope of unconsolidated material.
• Debris Flow Landslide - happens when the slope becomes saturated with water, this then triggers a landslide of water-soaked mass of rock and soil that slides down the slope.
• Rock Fall landslides - are sudden slides caused by heavy rain the rock on the slope loosens and then slides down the slope.
• Sinkhole - a topographic depression created when groundwater dissolves the underlying limestone bedrock. Often known as "sink" or "doline,".
• Types of Sinkholes:

  • Cover Collapse Sinkhole
  • Cover Subsidence Sinkhole
  • Dissolution Sinkhole
  • Artificial Sinkhole
• Cover Collapse Sinkhole - It develops suddenly (over an hour period) thus, causing catastrophic damage.
• Cover Subsidence Sinkhole - It gradually grows where the sediment covers are permeable and contain sand.
• Dissolution Sinkhole - It 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 .
• Geological Map - This type of map shows how geological features, rock units or geologic strata are shown by colors or symbols to indicate where they are exposed at the surface.
• Features of Geological Map

  ·      Fault

  ·      Tilts

  ·      Folds

  ·      Rock Layers
• Part of Geological Map:

  ·      Legend

  ·      Interpretation

  ·      Title

  ·      Susceptibility

  ·      Sources
• Symbols of Geological Map

  ·      Thick and Thin Lines

  ·      First Capitalized letter in geologic unit

  ·      Colors

  · Dotted contact line
• Different Movements of Fault

  ·      Normal Fault

  ·      Reverse Fault

  ·      Strike Slip Fault

  ·      Anticline

  ·      Plunging Syncline
• Geologic age and Formation Symbols

  
• Landslide Susceptibility

  
• Symbols and its interpretation

  
• Title

  
• Sources

  
• Coordinate System

  
• Legends

  
• Normal Fault

  
• Reverse Fault

  
• Strike-Slip Fault

  
• Anticline

  
• Plunging Syncline

  
• Mitigation - involves acting to reduce the risk of life or property damage from a potentially dangerous incident.
• If there’s frequent occurrence of landslides in a section, it implies that the soil in this area is weak and has unstable geology; thus, more susceptible to landslides. This may be caused by lack of vegetation, weathering, erosion, etc.
• A reactivated landslide is when an old, semi-stable landslide changed something, causing a new collapse at the same place.
• Tension cracks - These are caused by the stress and friction produced by geologic materials moving apart which forms steep lines of cracks in the terrain.
• HYDROMETEOROLOGICAL - a process or phenomenon of atmospheric, hydrological or oceanographic nature that may cause loss of life, injury or other health impacts, property damage, loss of livelihoods and services, social and economic disruption, or environmental damage.
• Tropical Cyclone -  also called typhoon or hurricane, an intense circular storm that originates over warm tropical oceans and is characterized by low atmospheric pressure, high winds, and heavy rain.
• WEATHER FORECAST - a scientific estimate of future weather condition, wherein a weather condition is a state of the atmosphere at a given time expressed in terms of the most significant variables.
• THUNDERSTORM - This is a powerful, short-lived weather disturbance, almost always associated with lightning, thunder, dense clouds, heavy rain or hail, and fast, roaring winds. Thunderstorms occur when layers of dry, moist air rise to cooler regions of the atmosphere in a broad, rapid updraft.