DRRR-2Q-week 1-2-lesson 1 and 2 Geological hazard, landslide and sinkholes

Disaster Readiness and Risk Reduction

  • Focus on understanding geological hazards, particularly landslides and sinkholes, and the importance of preparation and response strategies.

Geological Hazards

  • Definition: Geological hazards are natural events that can cause significant damage, including landslides and sinkholes.

Landslides

  • Description: A landslide is the downward movement of a large mass of rock, earth, or debris down a slope.

  • Types of Ground Movement:

    • Creep: Slow movement of soil particles.

    • Slump: Downward movement of rock debris.

    • Rockfall: Sudden collapses of rock.

    • Debris Flow: Mixture of water-soaked rock and soil.

    • Mudflow: Rapidly flowing mixture of mud and debris.

Causes of Landslides

Natural Causes

  • Climate: Changes in precipitation can destabilize slopes, affecting soil stability and groundwater levels.

  • Earthquakes: Seismic activity can trigger landslides, especially on steep slopes.

  • Weathering: Natural processes weaken rocks, making them susceptible to sliding.

  • Erosion: Running water can remove support from slopes and facilitate landslides.

  • Volcanic Eruptions: Wet eruptions can lead to flow of debris down slopes.

  • Forest Fires: Removes vegetation that stabilizes soil, increasing landslide risk.

  • Gravity: Increased slope steepness can enhance the potential for movement.

Human Causes

  • Mining Activities: Blasting and earthwork can destabilize soil and induce landslides.

  • Clear Cutting: Removes root systems that support soil, increasing erosion and landslide risk.

Signs of Impending Landslides

  • Previous Landslide Events: History of past landslides in the area.

  • Changes in Water Flow: Sudden water presence or disappearance may indicate instability.

  • Tension Cracks: Cracks in structures indicate ground movement nearby.

  • Ground Movement: Observable gradual shifts or signs of subsidence.

Sinkholes

  • Definition: A depression formed by the dissolution of bedrock, often limestone.

  • Characteristics: Sinkholes vary greatly in size and shape, can develop suddenly or gradually.

  • Types:

    • Cover Collapse Sinkhole: Sudden formation due to surface collapse.

    • Cover Subsidence Sinkhole: Gradual growth where permeable covering sediments exist.

    • Dissolution Sinkhole: Formed via the dissolution of underlying rocks.

    • Artificial Sinkhole: Resulting from human activities such as mining.

Causes of Sinkholes

Natural Causes

  • Dissolution of Sedimentary Rocks: Erosion can create voids that result in sinkholes.

Human Causes

  • Underground Water Pumping: Alters flow and can cause soil erosion.

  • Drainage Alterations: Improper management can facilitate erosion and sinkhole formation.

Signs of Impending Sinkholes

  • Visible Tilting of Structures: Trees or poles leaning dramatically.

  • Sudden Appearance of Ponds: Puddles forming unexpectedly.

  • Cracks in Ground: New or expanding cracks can indicate instability.

  • Subtle Changes: Uneven surfaces or dips in typical ground cover.

Geological Hazard Maps

  • Description: Maps displaying geological features, risks, and stability levels.

  • Components:

    • Legend, interpretation, and symbols used to denote hazards.

  • Interpretation of Susceptibility:

    • High risk indicated by landscape features such as steep slopes and recent landslide activity.

Mitigation Strategies

  • Community Preparedness: Profile at-risk locations, create disaster plans, and maintain emergency kits.

  • Structural Measures: New constructions should avoid hazardous zones; existing buildings should be evaluated for risk.

  • Non-structural Mitigation: Implement strategies such as anchoring heavy furniture and managing vegetation.

  • Government Role: Governments should model best practices in disaster resilience and regulation compliance.

Emergency Actions

Before a Hazard Event

  • Profile community risks, prepare emergency kits, consult hazard maps, and educate on safety measures.

During a Hazard Event

  • Stay alert, conduct evacuation as needed, and monitor local alerts.

  • Move quickly away from danger areas and adopt protective postures if trapped.

After a Hazard Event

  • Check for injuries, avoid entering dangerous areas, and provide information to emergency responders.