Geological Hazards: Landslides, Earthquakes

• Geological hazards are related to earth materials or processes like landslides, earthquakes, and sinkholes

• Geological hazards can turn into disasters for some communities

• Geological hazards can cause injury, disability, loss of home, income, or life

• Communities can reduce losses by:

  • Taking precautionary measures
  • Learning about preparedness and immediate response
  • Imbibing a culture of safety

• Objectives:

  • Discuss geological hazards
  • Analyze the causes of geological hazards
  • Recognize signs of impending geological hazards

Geological Hazards

• Geological hazards are natural earth processes that cause injury, loss of life, property damage, economic disruption or environmental changes
• Geological hazards include earthquakes, landslides, volcanic eruptions, and sinkholes

Landslide

• A landslide is rock, dirt, or debris falling down a slope
• Landslides are caused by storms, earthquakes, volcanoes or other factors that destabilize a slope

Three Major Causes of Landslides

• Geology: Refers to the soil or rock material and its stability in an area
• Morphology: Refers to the land structure; soil or rock weakened by loss of vegetation or prolonged rainfall/water leakage
• Human Activity: Includes agriculture, construction, deforestation, irrigation and excavation

Impending signs of a rainfall-induced landslide

• Rainfall-induced landslides can happen anytime during heavy rainfall

• Signs may include:

  • Unusual noises like breaking trees or boulders knocking
  • A slight rumbling sound that increases in amplitude
  • Rapid rise in creek water levels, followed by increased soil content

• The Early Warning System (EWS) from PHIVOLCS and PAGASA monitors and forecasts events to provide warnings on hazards

Sinkholes

• Sinkholes are depressions or holes caused by the collapse of the ground's surface layer

• Water is a primary cause, dissolving soluble rocks such as limestone, dolomite, and gypsum

• Two types of sinkholes: natural and man-made

• Natural sinkholes: Caused by physical or chemical erosion from water flow or acidic substances

• Man-made sinkholes: Caused by drilling, mining, road construction, or broken pipes

Types of Sinkholes

• Solution sinkholes: Common where there is a thin soil cover exposing bedrock to water erosion; bedrock erodes, particles collect, and a depression forms
• Cover subsidence sinkholes: Occur when bedrock is covered by poorly knitted soil; the soil erodes, and clay or sand enters cracks, creating a cavity
• Cover collapse sinkholes: Bedrock is covered by a deep layer of soil; cracks form as bedrock erodes, leading to weak points and sudden collapse

Impending signs of a sinkhole

• New cracks in building foundations and the ground
• Depressions at ground level
• Rapid appearance of a crater

Mitigation Strategies

• Landslides and sinkholes are natural disasters that can cause transportation route disruptions, property damage, injuries, and death

• On February 17, 2006, a landslide in the Southern Philippines caused 85 deaths and 981 missing individuals

• Mitigation strategies aims to avoid or eliminate such disasters

• Objectives:

  • Define, identify, and apply mitigation strategies
  • Synthesize or create an action plan
  • Value the benefits of understanding mitigation strategies

Mitigation

• Mitigation involves reducing the risk of life or property damage from a potentially dangerous incident
• There is no way to avoid natural disasters, but people and organizations may take steps to minimize the harm and losses that they cause
• Merriam-Webster defines mitigation as making something less severe, dangerous, painful, harsh, or damaging
• The National Academies Press describes mitigation as actions taken to prevent or reduce risk to life, social, economic and natural resources

Programs to Intensify Hazard Mitigation

• Protection of schools and hospitals:

  • Locate and construct to avoid high-hazard areas
  • Existing buildings should be surveyed to determine resistance levels

• Adoption of nonstructural measures:

  • Secure furniture and equipment
  • Vegetation management to reduce damage from wildfires
  • Structure position away from high-risk areas

• Incorporation of mitigation into new development:

  • Use hazard and risk assessment data
  • Land use plans and zoning regulations to limit development of hazard-prone areas

• Protection of cultural properties:

  • Preserve libraries, landmarks, historic buildings and art works.

• Protection of natural resources:

  • Identify valuable natural resources like endangered species of wildlife, fish, and plants
  • Apply protection measures in disaster response plans

• Government leadership:

  • Require new facilities to be designed, built, and located in accordance with modern building codes

• Mitigation training:

  • Training programs should emphasize challenges associated with mitigation implementation

• Hazard-specific research:

  • Recent disasters show the need for research to improve mitigation practices

Actions to Protect Human Lives and Properties

• Develop and rehearse a family disaster plan
• Include a communications plan
• Put emergency supplies together for home and car
• Know how to shut off appliances and keep resources at hand
• Duplicate important documents and keep originals in safe deposit
• Make a detailed inventory of personal belongings with photos/videos

Landslide Safety - Before

• Be familiar with your surroundings
• Watch for changes in objects' presence or positions
• Avoid open storm-water drainage and runoff
• Stay updated on news
• Be aware of local government disaster plans
• Learn and participate in emergency/evacuation plans

Landslide Safety - During

• Be attentive to unusual cracking objects, moving debris, and rolling boulders
• Stay away from the path of debris
• Stay alert and awake; listen for unusual sounds
• Stay on an elevated and sturdy area; avoid low-lying areas and steep slopes
• If escape is impossible, curl into a tight ball and protect your head

Landslide Safety - After

• Stay away from the slide area because of the danger of more landslides
• Listen for the latest emergency information
• Follow warnings and instructions from the local government
• If the landslide was caused by rainfall, watch out for flooding in the debris flow path
• Check for injured or trapped people and report to rescuers

Sinkhole

• Sinkholes, also known as cenotes, swallets, swallow holes, or dolines, are ground depressions caused by surface layer collapse
• Sinkholes are caused by chemical dissolution of carbonate rocks or suffosion
• Vary in diameter/depth from 1 to 600 m (3.3 to 2000 ft) and in shape
• Sinkholes may form gradually or suddenly; they are found worldwide

Sinkhole safety

• If a sinkhole appears suddenly, find refuge in a stable ground or open area
• Wait until the structures around the sinkhole stops moving
• Wait for the local government announcement when it is safe to go back

After a sinkhole appears

• Stay away from the sinkhole
• Monitor the damage to objects; if cracks lengthen/widen, the sinkhole may enlarge
• Do not throw anything into the sinkhole
• Secure properties and relocate to safe grounds away from the sinkhole's vicinity

Fire hazards

• Fire may start due to natural or human causes

Natural causes of fire

• Lightning, which can ignite combustible materials and cause forest fires
• Volcanic activity, where hot gases, ash and lava sparks fires
• Spontaneous combustion of hydrocarbon substances, or combustion of dry fuels (sawdust, dried leaves, grasses)

Human-made causes of fire

• Human errors or machine failures leading to wildfires or forest fires (machinery sparks, discarded cigarettes, arson)
• Housefires generally caused by human/machine error

Common causes of housefires

• Cooking equipment left unattended
• Portable heaters placed near flammable items
• Smoking in bedrooms
• Unattended candles
• Curious children playing with fire
• Faulty wiring
• careless barbeques