DRRR

• Geologic hazards


  Events that occur irregularly in time and space and cause negative impacts on man and the environment
• Geologic hazards


  • Involve the energy transformation of masses of soil, rocks, the lithosphere, and water in various combinations and conditions
  • Capable of causing damage or loss of property and life
• Sudden geologic phenomena

  • Avalanches
  • Earthquakes
  • Tsunamis
  • Forest fires
  • Volcanic Eruptions
  • Landslides and flash floods
• Landslide


  Down-slope movement of a mass of rock, debris, mud, or soil due to the direct influence of gravity
• Landslides


  • Occur in places characterized by steep or gentle slope gradients
  • Triggered by heavy rainfall, an earthquake, a slope cut to build a road, etc.
• Types of Landslide


  • Rotational Landslides
  • Translational Landslide
  • Block Landslide
  • Rock Fall Landslide
  • Topple
  • Debris Flow
  • Debris Avalanche
  • Creep
  • Lateral Spreads
• Rotational Landslides


  More resistant rocks founder over underlying weaker rocks, may produce spectacular whole mountainside collapse
• Translational Landslide


  Occur in very wet weather, when the near-surface soil and rock debris get saturated with water, and slides and flow downslope, can develop into more dangerous debris flows on steep ground
• Block Landslide


  Type of translational landslide, moving chunk of soil consists of a single unit or closely related units that move down the slope as a coherent mass
• Rock Fall Landslide


  Newly detached mass of rock falling from a cliff or down a very steep slope, the fastest type of landslide and occur most frequently in mountains
• Topple


  Failures distinguished by the forward rotation of units about some pivotal point, below or low in the unit, under the actions of gravity and forces exerted by adjacent units or by fluids in cracks
• Debris Flow


  Rapid mass movement in which loose soil, rock, organic matter, air, and water mobilized as slurry that flows down the slope
• Debris Avalanche


  Variety of very rapid to extremely rapid debris flow, one of the most dangerous kinds of landslide due to a huge chunk of land being saturated in a large area
• Creep


  Imperceptibly slow, steady, downward movement of slope-forming soil or rock, caused by shear stress sufficient to produce permanent deformation of soil
• Types of Creep

  • Seasonal
  • Continuous
  • Progressive
• Lateral Spreads


  Dominant mode of movement is lateral extension accompanied by shear or tensile fractures, caused by liquefaction and triggered by rapid ground motion
• Ground subsidence


  Relative lowering of the earth's surface usually with respect to the mean sea level
• Causes of ground subsidence

  • Carbonate dissolution and collapse
  • Excessive groundwater withdrawal
  • Extraction of oil and natural gas
• Coastal erosion


  Shapes shorelines by the wearing away of coastal land mainly by the impact of waves along the shoreline
• Five main causes of coastal erosion

  • Corrasion
  • Abrasion
  • Hydraulic action
  • Attrition
  • Corrosion/solution
• Engineering Geologist


  Provides recommendations and designs to mitigate geologic hazards
• Hydrometeorological hazards


  Involve the interaction of the atmosphere, bodies of water, and land and which pose threat to lives and human property
• Hydrometeorological hazards

  • Tropical cyclones
  • Thunderstorms
  • Hailstorms
  • Tornados
  • Blizzards
  • Heavy snowfall
  • Avalanches
  • Coastal storm surges
  • Floods including flash floods
  • Drought
  • Heatwaves and cold spells
• Precipitation


  All forms of water that fall from the atmosphere and reach the Earth, either liquid or solid form or transition between these forms
• Forms of precipitation

  • Rain
  • Snow
  • Sleet
  • Freezing rain
  • Hail
• Types of precipitation


  • Cyclonic precipitation
  • Convective Precipitation
  • Orographic precipitation
• Typhoon


  Severe weather disturbance with strong winds & heavy rains which revolve around a central low pressure area, derived from the Chinese term "Tai Fung" meaning "big wind"
• Major types of tropical cyclones

  • Tropical Depression
  • Tropical Storm
  • Typhoon
  • Super Typhoon
• Categories of tropical cyclones

  • 1: Wind speed of 74-95 mph
  • 2: Wind speed of 96-110 mph
  • 3: Wind speed of 111-130 mph
  • 4: Wind speed of 131-155 mph
  • 5: Wind speed of 156+ mph
• Tropical cyclone structure


  Air spirals in toward the center in a counter-clockwise pattern in the northern hemisphere, and out the top in the opposite direction
• The eye


  Clear area of sinking air and light winds, 20-40 miles across, develops when the maximum sustained wind speeds go above 74 mph, the calmest part of the storm
• The eyewall


  Strong wind gets as close as it can, consists of a ring of tall thunderstorms that produce heavy rains, the strongest winds, changes in the structure indicate changes in the storm's intensity
• Rainbands


  Curved bands of clouds and thunderstorms that trail away from the eye wall in a spiral fashion, capable of producing heavy bursts of rain and wind, & tornadoes
• Thunderstorms


  Short-lived weather disturbance associated with lightning, thunder, dense clouds, heavy rain or hail, and fast, roaring winds, essential ingredients are unstable air and moisture
• Types of thunderstorms


  • Orographic Thunderstorms
  • Air mass thunderstorms
  • Frontal thunderstorms
• Tornadoes


  Swiftly moving destructive vortex of violently rotating winds with the appearance of a funnel-shaped cloud, develop out of supercell thunderstorms
• Flood


  The overflow of water in dry land, inundation of a normally dry area caused by rising water level of an existing waterway
• Types of flood


  • River Flooding
  • Flash Flooding
  • Urban Flooding
• River flooding


  Most common forms of natural disaster, river fills beyond its capacity and the excess water overflows the river bank
• Flash flooding


  Sudden localized flood of great volume and short duration, where absorption, runoff, or drainage cannot disperse intense rainfall that is usually caused by thunderstorms