drrr quiz tom

• Geological hazard


  Natural phenomena that cause major problems around the world
• The expansion and development of cities has led to an increase in impact and damage due to geological hazards
• Most of the geological hazards are related to natural conditions, although some may be due to human activities
• Landslide


  Movement of ground, typically down a slope, caused by several factors including slope angle, gravity, and water-induced erosion
• Landslides commonly occur in sloping areas where water flows frequently, loosening the soil and making it susceptible to gravitational pull
• 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 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 Landslide


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


  Depression in the ground that is resulted from the collapse of the surface layer of the soil
• How sinkhole occurs

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

  2. As water passes through these cracks and fissures, it erodes the soil and forms a conduit system

  3. These underground water systems increase in size as the soil is carried by the water through internal erosion
• Types of sinkhole


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


  Sudden collapse of the ground causing catastrophic damage, develops for over an hour
• Cover Subsidence Sinkhole


  Develop gradually in areas where the covering sediments are permeable and sandy, small and can go unnoticed for long periods
• Dissolution Sinkhole


  Occur in areas where limestone is exposed at land surface or is covered by thin layers of soil and permeable sand, aggressive dissolution also occurs where flow is focused in pre-existing openings in the rock
• Artificial Sinkhole


  Caused by various human activities, including groundwater pumping and construction activities
• Natural causes of landslide

  • Climate
  • Earthquakes
  • Weathering
  • Erosion
  • Volcanic eruption
  • Forest fires
  • Gravity Dissolution of sedimentary rocks
• Long-term climatic changes


  Can significantly impact soil stability, a general reduction in precipitation leads to lowering of water table and reduction in overall weight of soil mass, reduced solution of materials and less powerful freeze-thaw activity
• Earthquakes


  Contribute to landslides worldwide by causing movement of tectonic plates, which also moves the overlying soil, particularly in areas with steep slopes
• Weathering


  Natural procedure of rock deterioration that leads to weak, landslide-susceptive materials, brought about by the chemical action of water, air, plants and bacteria
• Erosion


  Caused by sporadic running water such as streams, rivers, wind, currents, ice and waves, wipes out latent and lateral slope support enabling landslides to occur easily
• Volcanic eruption


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


  Wildfire removes the protective ability of vegetation which increases runoff, erosion, and debris flow, particularly the risk of landslides prevailing or up to 20 years in dry climates
• Gravity


  Steeper slopes coupled with gravitational force can trigger a massive landslide, steeper slopes can also cause the debris to move farther from the foot of the area
• Human causes of landslide

  • Mining
  • Clear cutting Underground water pumping
• Mining


  Activities that utilize blasting techniques contribute mightily to landslides, vibrations emanating from the blasts can weaken soils in other areas susceptible to landslides
• Clear cutting


  Technique of timber harvesting that eliminates all old trees from the area, dangerous since it decimates the existing mechanical root structure of the area, changes the amount of water infiltrating the soil
• Rainfall-induced landslides


  The most common and widespread damaging landslides in the Philippines, with an average of 20 typhoons each year due to prolonged or heavy rainfall, most are shallow, thin, and move quickly
• Natural causes of sinkhole

  Dissolution of sedimentary rocks, when sedimentary rocks are dissolved, holes or depression in the ground can be form
• Human causes of sinkhole

  Underground water pumping, pumping water underneath the ground causes drainage to alter their flow which causes the soil to be eroded by water
• Dissolution of Sedimentary Rocks

  When sedimentary rocks are dissolved, holes or depression in the ground can be form.
• There are two types of landslides: mass wasting and mass failure.
• Landslide is defined as the movement of rock, debris, or earth down a slope under the influence of gravity.
• Sinkholes caused by human activities include underground water pumping, where pumping water underneath the ground alters the flow of drainage causing soil erosion by water.