DRRR

• Sinkholes

  • Occur in areas where the soil foundation is made of soft minerals and rocks such as limestone, salt beds, or any acidic rocks
  • The depth of sinkholes ranges from a couple of meters to several miles deep
• How sinkholes occur

  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

  4. This can either form a void filled with air with an underground drainage

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

  6. Otherwise it forms a hole once the cover collapses into the void which can be either filled with air or
• Types of sinkholes

  • 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 sand is exposed on the ground and permeable sand is also covered. Limestone or dolomite dissolution is most intense when the water first reaches the rock surface
• Causes of geologic hazards

  • Climate
  • Earthquakes
  • Weathering
  • Flooding
  • Volcanic Activity
  • Forest Fires
  • Gravity
  • Mining
  • Clear cutting of trees
• Any of the triggers are only caused by a triggering element. A landslide can be caused by a natural or mechanical factor/human