MEV 002: Block-1 (Unit 01) – Introduction to natural hazards and disaster

-

 UNIT 1: INTRODUCTION TO NATURAL HAZARDS AND DISASTER

1.0 Introduction

Natural hazards and disasters have shaped human civilization for centuries. From earthquakes and floods to cyclones and volcanic eruptions, the Earth’s dynamic systems can cause extensive damage and disrupt societies. With growing population density, unplanned urbanization, and increased environmental degradation, the impact of natural hazards is more severe today than ever before.

Understanding the nature, causes, and consequences of these hazards is critical for planning, risk reduction, and disaster management. This unit introduces the fundamental concepts related to natural hazards, their classifications, impacts, and the international strategies developed to address them.

1.1 Objectives

After studying this unit, learners will be able to:

  • Define and differentiate between hazards and disasters.
  • Classify various types of natural hazards.
  • Understand the physical, social, economic, and psychological impacts of disasters.
  • Analyze the role of human intervention in increasing vulnerability.
  • Examine global strategies for disaster risk reduction and management.

1.2 Hazards and Disaster

A hazard is a potentially damaging physical event or phenomenon that may cause loss of life, injury, property damage, social and economic disruption, or environmental degradation. Hazards become disasters when they cause significant disruption to human society.

A disaster, therefore, is a serious disruption of the functioning of a community or society involving widespread human, material, economic, or environmental losses and impacts that exceed the ability of the affected community to cope using its own resources.

Key Differences:

Aspect

Hazard

Disaster

Nature

Potential threat

Actual event

Impact

May or may not cause damage

Causes significant damage

Example

Earthquake fault line

2001 Gujarat Earthquake

1.3 Dimensions of Hazard

Hazards can be characterized based on several dimensions:

  • Frequency: How often the hazard occurs.
  • Duration: The time span over which the hazard exerts its effects.
  • Predictability: The degree to which the occurrence of the hazard can be forecast.
  • Intensity and Magnitude: The strength and scale of the hazard.
  • Speed of Onset: How quickly the hazard impacts a region after its initiation.
  • Areal Extent: The geographic area affected.

Understanding these dimensions helps in planning and mitigation efforts.

1.4 Hazards Classification

Hazards are classified into two broad categories:

  1. Natural Hazards – Arise from natural processes.
    • Geophysical (e.g., earthquakes)
    • Hydrological (e.g., floods)
    • Meteorological (e.g., cyclones)
    • Climatological (e.g., droughts)
    • Biological (e.g., epidemics)
  2. Anthropogenic (Man-made) Hazards – Caused by human activity.
    • Technological (e.g., industrial accidents)
    • Environmental degradation (e.g., deforestation)

1.5 Types of Natural Hazards

Here are some major types of natural hazards:

  1. Earthquakes: Sudden shaking due to tectonic movements.
  2. Volcanic Eruptions: Release of magma, ash, and gases.
  3. Floods: Overflow of water bodies inundating normally dry land.
  4. Droughts: Extended period of deficient rainfall.
  5. Cyclones: Intense wind systems with heavy rainfall.
  6. Tsunamis: Large sea waves triggered by undersea earthquakes.
  7. Landslides: Downward movement of soil and rock.

1.6 Effects and Service Functions of Natural Hazards

While natural hazards often cause devastation, they also serve ecological functions.

Negative Effects:

  • Loss of lives and property
  • Economic instability
  • Environmental degradation
  • Displacement and migration

Positive (Service) Functions:

  • Floods replenish alluvial soil.
  • Volcanoes create fertile land.
  • Natural fires maintain forest health in some ecosystems.

Understanding both effects helps develop a balanced approach to disaster management.

1.7 Disaster and Socio-economic Impacts

1.7.1 Social Impact

  • Displacement of people
  • Breakdown of social infrastructure
  • Disruption of education and healthcare services

1.7.2 Economic Impact

  • Loss of livelihood and productivity
  • Damage to infrastructure and housing
  • Cost of emergency relief and rehabilitation

1.7.3 Psychosocial Impact

  • Trauma, anxiety, and depression
  • Increase in domestic violence and social unrest
  • Loss of community cohesion

1.8 Vulnerability and Human Intervention

Vulnerability refers to the conditions that increase the susceptibility of a community to the impact of hazards. It is influenced by:

  • Poverty and inequality
  • Poor infrastructure
  • Inadequate planning and governance
  • Environmental degradation (e.g., deforestation, wetland loss)

Human actions often convert natural hazards into disasters by increasing exposure and reducing resilience.

1.9 Overview of Assessing Hazards

Assessment involves identifying potential hazards, evaluating the risks, and estimating the possible impacts. Key components include:

  • Hazard Mapping: Identifying vulnerable areas.
  • Risk Assessment: Combining hazard likelihood with vulnerability.
  • Preparedness Planning: Developing response strategies and early warning systems.

This systematic approach guides urban and rural development, infrastructure design, and disaster policy.

1.10 Natural Disasters: International Attention and Strategies

Global efforts for disaster risk reduction have grown in the 21st century. Key initiatives include:

  • Hyogo Framework for Action (2005–2015): Aimed to build the resilience of nations and communities.
  • Sendai Framework for Disaster Risk Reduction (2015–2030): Emphasizes understanding risk, governance, and investing in disaster resilience.
  • UNISDR (now UNDRR): United Nations Office for Disaster Risk Reduction promotes international cooperation.
  • SDGs (Goal 11 and 13): Promote sustainable cities and climate action.

1.11 Let Us Sum Up

In this unit, we explored the fundamental concepts of natural hazards and disasters. We distinguished between hazards and disasters, analyzed their types and impacts, and emphasized the role of human actions in influencing vulnerability. The unit also highlighted international strategies for risk reduction and the importance of planning and preparedness in building disaster-resilient communities.

1.12 Keywords

  • Hazard: A potentially damaging physical event.
  • Disaster: A serious disruption due to hazard impact.
  • Vulnerability: Susceptibility to harm from hazards.
  • Risk Assessment: Evaluation of hazard-related threats.
  • Sendai Framework: Global strategy for disaster risk reduction.

 

Comments

Post a Comment

Popular Posts

Jcert Class 8 Daffodil Chapter 1a: The Naive Friends Solutions

-
Chapter 1a : The Naive Friends Answer the following questions: 1. Which questions made Keshav and Shyama curious about the egg? Ans.         How did the chick come out? How big would the eggs? How many? What colours would they? What did they eat? Such types of questions made Keshav and Shyama curious about the egg. 2. What three things did the children do to protect the eggs? Ans.         The children done three things are: (i)          Adjustment of food. (ii)        Adjustment of water. (iii)      Adjustment of roof. 3. Why did Keshav think of making a cushion for the eggs? Ans.         When Keshav saw the egg on direct sun light, he thaught making a cushion for the eggs. 4. What excuse did Keshav give for not showing the eggs to Shyama? Ans.     ...
Read more

Jcert Class 8 भाषा मंजरी Chapter 3 मित्रता Solutions

-
अध्याय - 3 : मित्रता 1. आप किस प्रकार कह सकते हैं कि मित्रों के चुनाव की उपयुक्तता पर हमारे जीवन की सफलता निर्भर करती है? उ. मित्रों के चुनाव की उपयुक्तता पर हमारे जीवन की सफलता निर्भर करती है क्योंकि संगति का गुप्त प्रभाव हमारे आचरण पर पड़ता है और यदि हमें अच्छी संगति, अच्छे मित्र मिलते हैं तो वे हमें सफलता की ओर ले जाते हैं जबकि बुरी संगति हमारे जीवन को खाक में मिला देती है।  2. 'विश्वासपात्र मित्र जीवन की एक औषध है।' आशय स्पष्ट कीजिए। उ. 'विश्वासपात्र मित्र जीवन की एक औषध है'- ऐसा इसलिए कहा गया है कि यदि हमें विश्वासी मित्र मिल गया तो हम अपने जीवन में चाहे जैसा भी कदम उठाएँ, उस कदम की आलोचना करके वह हमें सही दिशा की ओर उन्मुख करेगा। हम अपनी गलती रूपी बीमारी को उसकी आलोचना रूपी औषधि से दूर कर सकेंगे।  3. मित्र का चुनाव करते समय हमें किन बातों का ध्यान रखना चाहिए? उ. मित्र का चुनाव करते समय हमें निम्नलिखित बातों का ध्यान रखना चाहिए हमारे अच्छे विचारों (संकल्पों) को दृढ़ करने वाला हो। हमें दोषों और त्रुटियों से बचाए। हमारे सत्य, पवित्रता ...
Read more

Jcert Class 8 भाषा मंजरी Chapter 8 अमरूद का पेड Solutions

-
अध्याय - 8 : अमरूद का पेड 1. लेखक को क्यों लगता है कि इन सब पिछड़े खयालातों का हमारे घर में गुजर नहीं हो सकेगा। उ. अमरूद के पेड़ को देखकर सबसे पहले बाबू कन्हैयालाल की बूढ़ी पत्नी ने एक दिन टोका कि पश्चिम की तरफ अगर मकान का मुखड़ा हो और सामने ही अमरूद का पेड़ तो 'राम-राम बड़ा अशुभ होता है और माँ के चेहरे पर थोड़ा-सा भय दिखा पर लेखक को विश्वास था कि इन सब पिछड़े खयालातों का हमारे घर में गुजर नहीं हो सकेगा क्योंकि उसके घर के लोग आधुनिक विचारधारा के थे उसकी माँ सत्याग्रह के दिनों में अजमेर में लम्बा जेल कर चुकी है। पिताजी खुद राजनैतिक सामाजिक उदारता वाले आदमी थे। बुआ ने विवाह नहीं किया था, पढ़ने-लिखने में ही अपनी सम्पूर्ण जिन्दगी लगा दी और समाज कोई चुनौती देने का साहस नहीं कर सका। साथ ही परिवार के सभी लोगों में पिछड़ेपन के प्रति भर्त्सना का भाव था। 2. अमरूद के पेड़ की छाया किस प्रकार लेखक को उनके भाई-बहनों के साथ जोड़ती है ? उ. अमरूद के पेड़ की छाया लेखक को उसके भाई-बहनों के साथ जोड़ती है। वे सभी अमरूद की छाया में बेंत की कुर्सियों पर बैठ चर्चाएँ करते थे जिससे उनके बीच...
Read more