DRRR-Midterms

Key Concepts of Disaster Risk Management

Definition of Disaster Risk

  • Disaster Risk = Hazard × Vulnerability

  • More detailed: Disaster Risk = Hazard × Exposure × Vulnerability

Understanding Vulnerability

  • Definition (IFRC): Diminished capacity of individuals or groups to anticipate, cope with, resist, and recover from hazards.

  • Definition (UN Office for Disaster Risk Reduction): Characteristics and circumstances of a community which make it susceptible to hazards.

  • Vulnerability is situation-specific and hazard-specific.

Factors Affecting Vulnerability

  • Proximity to Hazard: Areas frequently hit by hazards have higher vulnerability.

  • Population Density: High population density in exposed areas increases vulnerability.

  • Capacity to Reduce Risk: Accessibility and availability of services for disaster preparedness.

  • Building Codes: Structures designed to withstand disasters lower community vulnerability.

Exposure Definition

  • Definition (Geoscience Australia): Elements at risk from hazards including:

    • Individuals

    • Households/Communities

    • Properties

    • Buildings and structures

    • Agricultural commodities

    • Livelihoods

    • Public facilities and infrastructure

    • Environmental assets

  • Greater exposure leads to higher disaster risk.

Elements Exposed to Hazard

  1. Physical Elements: Tangible aspects e.g. landscapes, buildings.

  2. Socioeconomic Elements: Institutional systems and community well-being e.g. communication, transportation.

  3. Environmental Elements: Ecosystems and natural processes affected by human activity.

Transforming Hazard into Disaster

  • A hazard turns into a disaster when there is:

    • Community exposure to the hazard.

    • Community vulnerability.

Relationship Between Hazard, Vulnerability, and Exposure

  • High vulnerability and exposure to hazards greatly increase disaster risk.

Assessing Exposure and Vulnerability

Exposure to Physical Elements

  • Population metrics:

    • How many people live nearby?

    • Nearby bodies of water and landforms?

    • Structures that may collapse?

Exposure to Socioeconomic Elements

  • Community interactions and how they may be affected during disasters.

Exposure to Environmental Elements

  • Dependency on natural resources and impacts on local flora and fauna from hazards.

Vulnerability Assessment Criteria

  1. Proximity to Disaster: Direct exposure to frequent hazards raises vulnerability.

  2. Population Density: A larger population in exposed areas increases impact severity.

  3. Capacity to Reduce Risk: Lack of disaster preparedness plans raises difficulty in facing hazards.

  4. Building Codes: Weak structures in hazard-prone areas increase vulnerability.

Profiling Hazards

  • Hazards profiled based on:

    1. Magnitude or Strength: Measured using scientific instruments.

    2. Frequency: How often a hazard occurs.

    3. Duration of Impact: Short-term vs. long-term effects.

    4. Causality of Events: Direct vs. indirect impacts.

Impact of Hazards

  1. Physical Elements: Consider damage and survival rates.

  2. Socioeconomic Elements: Communication and transport disruptions.

  3. Environmental Elements: Both negative and positive changes may arise, such as opportunities for growth post-disaster.

Earthquake Fundamentals

Definition

  • Earthquake: Sudden shaking of the ground caused by tectonic movements.

Causes of Earthquakes

  1. Convergent Boundaries: Plates collide, forming mountains.

  2. Divergent Boundaries: Plates separate, magma rises to create crust.

  3. Transform Boundaries: Plates slide past each other, causing intense shaking.

Earthquake Measuring Criteria

  • Magnitude: Energy released measured at the source.

  • Intensity: Strength of shaking and impact variation across locations.

Reasons for Frequency in the Philippines

  1. Geographic location: Located in the Pacific Ring of Fire.

  2. Philippine Fault System: Major geological faults interconnected across the archipelago.

Potential Earthquake Hazards

  1. Ground Shaking: Caused by seismic waves; intensity varies.

  2. Ground Rupture: Movement along faults that surface.

  3. Liquefaction: Saturated soil behaves like quicksand under shaking.

  4. Ground Subsidence: Lowering of ground due to various factors.

  5. Tsunamis: Sudden displacement in water from seismic activity.

  6. Earthquake-Induced Landslide: Land collapses triggered by seismic shaking.

Early Warning Signs

  • Seismometer: Measures earth surface movements.

  • Seismic Waves: Primary (P-waves) and secondary (S-waves).

Precautionary and Safety Measures for Earthquakes

Before an Earthquake

  • Prepare a survival kit with essentials such as food and water.

  • Secure heavy furniture and breakable items.

During an Earthquake

  • Indoors: Duck under furniture and protect head.

  • Outdoors: Stay clear of buildings and debris.

  • In vehicles: Turn on hazard lights and remain inside.

After an Earthquake

  • Expect aftershocks; check for injuries.

  • Avoid damaged areas and report power line issues.

Volcanic Hazards

Why Do We Have Volcanoes?

  • Earth’s crust is broken into tectonic plates, with volcanic activity prevalent at plate edges.

Types of Volcanic Hazards

  1. Lahar: Mixture of water and volcanic materials flowing down slope.

  2. Ash Fall: Pulverized rock fragments damaging property and health.

  3. Pyroclastic Flow: Fast-moving mixture of rock fragments and gas.

  4. Ballistic Projectiles: Ejected rock fragments during eruptions.

  5. Volcanic Gas: Toxic gases from magma.

  6. Lava Flow: Molten rock flowing from a volcano, destructive to the landscape.

Signs of Impending Eruptions

  1. Increased earthquake activity.

  2. Ground deformation and cracks.

  3. Increased gas emissions and temperature.

  4. Crater glow due to rising magma.

  5. Changes in vegetation and water color near the volcano.

Volcanic Safety Measures

Before an Eruption

  • Stay updated on local news and community plans.

  • Prepare an emergency supply kit.

During an Eruption

  • Follow evacuation orders; stay indoors with all windows sealed.

After an Eruption

  • Wait for safety announcements before returning home.

  • Wear protective gear during cleanup to avoid ash inhalation.