UNIT I – INTRODUCTION TO DISASTERS

1. Introduction

A disaster is a serious disruption of the functioning of a community or society causing widespread human, material, economic, or environmental losses that exceed the ability of the affected community to cope using its own resources. Disaster management focuses on understanding disasters, reducing risks, and preparing societies to respond effectively.

2. Key Definitions

2.1 Disaster

A disaster is an event, natural or man-made, that causes significant damage to life, property, and the environment, leading to disruption of normal life.

2.2 Hazard

A hazard is a potentially damaging physical event, phenomenon, or human activity that may cause loss of life, injury, property damage, or environmental degradation.

2.3 Vulnerability

Vulnerability refers to the conditions determined by physical, social, economic, and environmental factors that increase the susceptibility of a community to the impact of hazards.

2.4 Resilience

Resilience is the ability of a system, community, or society to resist, absorb, adapt to, and recover from the effects of a disaster efficiently.

2.5 Risk

Risk is the probability of harmful consequences resulting from the interaction between hazards and vulnerable conditions.

Risk = Hazard × Vulnerability / Capacity

3. Types of Disasters

Disasters can broadly be classified into Natural Disasters and Man-made (Anthropogenic) Disasters.

3.1 Natural Disasters

a) Earthquakes

Sudden shaking of the earth caused by the release of energy along fault lines.

Causes: Tectonic plate movements
Impacts: Loss of life, infrastructure collapse, tsunamis, landslides

b) Landslides

Downward movement of soil, rock, or debris due to gravity.

Causes: Heavy rainfall, earthquakes, deforestation
Impacts: Burial of settlements, road blockages

c) Floods

Overflow of water submerging land that is usually dry.

Causes: Heavy rainfall, dam failure, river overflow
Impacts: Crop damage, displacement, waterborne diseases

d) Drought

Prolonged period of deficient rainfall leading to water scarcity.

Causes: Climate variability, deforestation
Impacts: Famine, migration, economic loss

e) Fire

Uncontrolled burning causing damage to forests, property, and life.

Causes: Natural (lightning), human negligence
Impacts: Air pollution, habitat loss

3.2 Man-made Disasters

a) Industrial Disasters

Accidents occurring in industrial settings.

Examples: Gas leaks, explosions, chemical spills
Impacts: Toxic exposure, long-term health issues

b) Technological Disasters

Failures of technology or infrastructure.

Examples: Nuclear accidents, power grid failures
Impacts: Environmental contamination, social disruption

4. Climate Change and Disasters

Climate change increases the frequency and intensity of disasters such as floods, droughts, heatwaves, and cyclones. Rising global temperatures alter weather patterns, making communities more vulnerable.

5. Classification of Disasters

By Origin: Natural, Man-made
By Speed of Onset: Sudden (earthquakes), Slow-onset (droughts)
By Scale: Local, Regional, Global

6. Causes of Disasters

Natural processes
Environmental degradation
Rapid urbanization
Poor planning and governance
Climate change

7. Impacts of Disasters

Human: Death, injury, psychological trauma
Economic: Loss of livelihood, infrastructure damage
Environmental: Ecosystem destruction
Social: Displacement, poverty

8. Dos and Don’ts During Disasters (General)

Dos

Stay calm and alert
Follow official warnings
Keep emergency kits ready
Help vulnerable people

Don’ts

Do not panic
Avoid rumors
Do not use damaged infrastructure
Avoid risky areas

9. Global Trends in Disasters

9.1 Urban Disasters

Disasters intensified by unplanned urbanization such as building collapse, urban flooding, and fires.

9.2 Pandemics

Large-scale outbreaks of infectious diseases affecting global populations.

9.3 Complex Emergencies

Situations involving conflict, displacement, and humanitarian crises.

9.4 Climate Change–Induced Disasters

Increasing frequency of extreme weather events due to global warming.

10. Important Exam Points

Definitions of disaster, hazard, vulnerability, resilience, and risk
Types and classification of disasters
Role of climate change in disasters
Global disaster trends

11. Sample Questions

Short Answer

Define disaster and hazard.
What is vulnerability?
List any four natural disasters.

Long Answer

Explain types of disasters with examples.
Discuss the impacts of climate change on disasters.
Explain global trends in disasters.

12. Text-Based Diagrams & Flowcharts

12.1 Disaster Risk Relationship

Hazard ───┐
          ├──► RISK ───► Disaster Impact
Vulnerability ─┘

(High Hazard + High Vulnerability = High Risk)

12.2 Disaster Management Cycle (Introductory)

Mitigation ─► Preparedness ─► Response ─► Recovery
      ▲                                      │
      └─────────────── Feedback ────────────┘

12.3 Classification of Disasters

Disasters
├── Natural
│   ├── Earthquake
│   ├── Flood
│   ├── Drought
│   └── Landslide
└── Man-made
    ├── Industrial
    ├── Technological
    └── Urban Disasters

12.4 Impacts of Disasters

Disaster
├── Human Loss
├── Economic Loss
├── Environmental Damage
└── Social Disruption

13. Question Bank with Answers

13.1 Very Short Answer (2 Marks)

Q1. Define Disaster.
A disaster is a sudden or progressive event causing widespread damage to life, property, and environment beyond the coping capacity of the affected community.

Q2. What is a hazard?
A hazard is a potentially damaging event or phenomenon that may cause loss of life or property.

Q3. Define vulnerability.
Vulnerability is the degree to which a system or community is susceptible to damage due to hazards.

Q4. What is resilience?
Resilience is the ability to resist, absorb, and recover from disaster impacts.

13.2 Short Answer (5 Marks)

Q5. Explain the relationship between hazard, vulnerability, and risk.
Risk arises when a hazard affects a vulnerable population. Higher vulnerability increases disaster risk even if hazard intensity remains constant.

Q6. List and explain any four natural disasters.
Earthquake, flood, drought, and landslide are common natural disasters causing severe damage to life and infrastructure.

Q7. Write short notes on urban disasters.
Urban disasters occur due to high population density, unplanned construction, and inadequate infrastructure.

13.3 Long Answer (10 Marks)

Q8. Classify disasters and explain each with examples.
Disasters are classified into natural and man-made. Natural disasters include earthquakes and floods, while man-made disasters include industrial and technological accidents.

Q9. Discuss climate change as a global disaster trend.
Climate change increases extreme events like floods, droughts, heatwaves, and cyclones, increasing disaster frequency and intensity worldwide.

14. Student-Friendly Notes (Simplified)

Key Points to Remember

Disaster = Hazard + Vulnerability
Natural disasters are unavoidable but manageable
Man-made disasters can be reduced with planning
Climate change is increasing disaster risk globally

Easy Definitions

Hazard: Something that can cause harm
Vulnerability: How weak or exposed people are
Resilience: Ability to recover after disaster

15. தமிழ் (Tamil) – Unit I Summary (Student-Friendly)

பேரிடர் என்றால் என்ன?

பேரிடர் என்பது மனித உயிர், சொத்து மற்றும் சுற்றுச்சூழலுக்கு பெரும் சேதத்தை ஏற்படுத்தும் இயற்கை அல்லது மனிதனால் உருவான நிகழ்வாகும்.

முக்கிய சொற்கள்

அபாயம் (Hazard): சேதத்தை ஏற்படுத்தக்கூடிய நிகழ்வு
பாதிப்பு (Vulnerability): பேரிடரால் பாதிக்கப்படும் நிலை
மீட்பு திறன் (Resilience): பேரிடருக்குப் பிறகு மீண்டு வரும் திறன்
ஆபத்து (Risk): அபாயம் மற்றும் பாதிப்பு இணைவு

பேரிடர்களின் வகைகள்

இயற்கை பேரிடர்கள்: நிலநடுக்கம், வெள்ளம், வறட்சி
மனிதனால் உருவான பேரிடர்கள்: தொழிற்சாலை விபத்துகள், தொழில்நுட்பக் கோளாறுகள்

தேர்விற்கு முக்கியமானவை

வரையறைகள்
பேரிடர் வகைகள்
காலநிலை மாற்றம்
பேரிடர் விளைவுகள்

UNIT #1 Intro to Disaster Management