Natural and Man-made Disasters Chapter Notes | Geography Class 8 ICSE PDF Download

Introduction

Natural and Man-made Disasters

• A disaster is a major accident or catastrophe that happens quickly.
• It leads to loss of life, property, and damage to the economy and environment.
• Recovery can take a long time due to the scale of destruction.
• Developing countries face greater impact, with over 95% of disaster deaths occurring there.
• Recovery costs in developing countries are 20 times higher (as a percentage of GDP) than in industrialized nations.
• Disasters are classified into natural and man-made types.

Natural Disaster

• Natural disasters are catastrophic events caused by nature or Earth's processes.
• Their severity is measured by lives lost, economic damage, and the ability to rebuild.
• Events in unpopulated areas are not considered disasters.
• Example: A flood on an uninhabited island is not a disaster, but one in a populated area is.
• All natural disasters cause losses, including lives, property, transportation, and livelihoods.
• Deaths can occur from freezing, being washed away, or heat stroke, depending on the disaster.
• Scientists, geologists, and meteorologists use technology to predict major storms, blizzards, and cyclones.
• Some natural disasters still occur unexpectedly despite advanced technology.

Types of Natural Disasters

Floods

• Floods happen when water accumulates in an area, covering land not usually underwater.
• They can occur in any environment with water, even deserts.
• In India, many states face flooding during the monsoon season.

Causes

• Caused by heavy rains, strong winds, cyclones, tsunamis, melting snow, or dam bursts.
• Floods can happen gradually or suddenly due to intense rainfall or broken water control structures.

Effects

• Many humans and livestock die from drowning or severe injuries.
• Epidemics like diarrhoea, cholera, jaundice, or viral infections may spread.
• Shortage of safe drinking water occurs as wells get submerged.
• Mud huts and weak buildings collapse, and roads, rails, dams, monuments, and crops are damaged.
• Utilities like water supply, sewage, communication, power lines, and transportation networks are at risk.

Safety Measures

During a Flood

• Avoid walking through moving water.
• Do not drive into flooded areas.
• Do not touch electrical equipment if wet or standing in water.

After a Flood

• Return home only when authorities say it is safe.
• Stay out of buildings surrounded by floodwater.
• Repair damaged septic tanks, cesspools, pits, and leaching systems quickly, as they pose health risks.

Earthquakes

• Earthquakes are sudden energy releases in the Earth’s crust due to tectonic plate movement.
• They strike without early warning and are measured using the Richter Scale.
• Around 500,000 earthquakes occur globally each year.

Causes

• Result from sudden breaks or cracks in the Earth’s upper crust.
• These breaks can cause the surface to crack and the ground to vibrate.

Effects

• Ground shaking varies based on earthquake strength, distance from the epicentre, and local geology.
• Longer shaking causes greater damage.
• In mountains, earthquakes weaken slopes, leading to landslides and avalanches.
• Undersea earthquakes can produce tsunamis, causing devastation along coasts.
• Shock waves cause liquefaction, turning soft ground to mud as groundwater rises.

Fact Corner

• Earthquakes form hot springs, which benefit people.
• They can submerge coastal lands, creating inlets, bays, and gulfs useful for fishing and shipping.
• They bring fertile shores out of the water, forming new coasts.

Safety Measures

• Drop down, take cover under a desk or table, and hold on.
• Move to an open space if possible; otherwise, stay indoors until shaking stops and it’s safe to exit.
• Avoid bookcases or furniture that can fall.
• Stay away from windows; in high-rise buildings, expect fire alarms and sprinklers to activate.
• If in bed, stay there and protect your head with a pillow.
• If outdoors, find a clear spot away from buildings, trees, and power lines, and drop to the ground.
• If in a car, slow down, drive to a clear place, and stay inside until shaking stops.

Droughts

• Droughts occur when an area lacks rainfall or precipitation for a long period.
• They can last from a month to several years.
• They harm ecosystems, agriculture, and the economy.
• India faced severe droughts like the Bengal famines of 1779, 1876-1877, and 1899, each killing millions.
• Droughts in India are linked to the El Niño effect.

Volcanic Eruptions

• Volcanoes are vents in the Earth’s crust where magma from the upper mantle erupts.
• Eruptions occur when pressure builds, releasing hot lava, lateral blasts, ash, and avalanches.
• They can trigger flash floods, tsunamis, mudflows, earthquakes, and rockfalls.

Cyclones

• Cyclones are spinning storms rotating around a low-pressure centre called the 'eye'.
• The eye is calm, but the spinning arms cause great damage.
• They can rip roofs off houses, destroy buildings, or move them to new locations.
• Other effects include floods and large-scale evacuations to emergency shelters, often leaving people homeless.

Tsunamis

• Tsunamis, meaning 'harbour wave' in Japanese, are giant waves from ocean water displacement.
• Caused by earthquakes, volcanic eruptions, landslides, or glacier calvings in oceans.
• The 2004 Indian Ocean tsunami killed 230,000-280,000 people and caused destruction in 14 countries, including Indonesia, Sri Lanka, India, and Thailand.

Landslides

• Landslides involve land, rocks, and debris falling down mountains or cliffs at high speeds.
• They can happen worldwide, on any surface, including land and underwater.
• Causes are both natural and man-made, with effects ranging from minor to severe devastation.

Wildfires

• Wildfires are uncontrollable fires sparked by lightning or volcanic eruptions meeting combustible vegetation.
• Types include forest fires, grass fires, bush fires, and hill fires.
• Severity depends on flammable material, weather, vegetation density, and topography.
• They cause the loss of many ecosystems.

Effects of Natural Disasters

• Natural disasters have become so common that they hardly receive much attention on the news unless there are a large number of casualties.
• Volcanoes, mudslides, tsunamis and floods are just a few of the ways nature strikes on a daily basis, leaving behind destruction and hardship.
• Humans have learned to prepare for the possibility of tornadoes, earthquakes, hurricanes and wildfires, but no amount of preparation can decrease the impact that natural disasters have on every aspect of society.

Physical Destruction

• The biggest visible effect of natural disasters is the physical devastation they leave behind.
• Homes, vehicles and personal possessions are often destroyed within a short period of time, leaving families homeless and shutting down the affected businesses permanently.
• Cyclones destroy structures at a whim, earthquakes can cause structural damage that might not be apparent at first glance, and tsunamis and floods sweep homes off their foundations.

Emotional Toll

• Disasters take a heavy emotional toll, displacing communities and separating friends and neighbors.
• Victims face anxiety, depression, and fear of recurrence.
• In extreme cases, people may suffer from post-traumatic stress disorder (PTSD).

Economic Concerns

• Over 40 years, economic losses from natural disasters have increased ninefold.
• Hurricane Katrina was the costliest tropical cyclone, with the season causing $209 billion in losses.
• Rebuilding and rescue efforts require huge financial resources.

Environment

• Animals are displaced and may need to adapt to new habitats.
• Volcanoes, earthquakes, floods, wildfires, and mudslides permanently change landscapes.
• Some local species may face extinction due to these changes.

Man-made Disasters

• Man-made disasters result from human actions.
• Examples include hazardous material spills, explosions, chemical or biological attacks, nuclear blasts, and traffic collisions like train or plane crashes.
• Most are accidents, except for attacks, and cause deaths, injuries, and property loss.
• Also called anthropogenic disasters.

Types of Man-made Disasters

Nuclear Disasters

• A nuclear disaster is the emission of large amounts of radioactive substances from nuclear power plants.
• If we breathe in these radioactive substances or get exposed to radiation emitted from radioactive substances, our bodies will be adversely affected.

Biological Disasters

• Biological and nuclear weapons are referred to as the poor man’s nuclear bomb as these are easy to manufacture and transport.
• However, they can still kill or harm hundreds and thousands of people.
• They are delivered using dusting airplanes or small perfume atomisers and have the ability to generate immediate and disastrous effects.

Chemical Disasters

• Chemical Disasters are disasters that are caused due to the excessive use and misuse of chemicals in industries. 
•  The irresponsible handling of powerful chemicals can cause widespread destruction. 
•  Industries using harmful and powerful chemicals should be located far away from residential areas.

Travel Accidents 

• Major air, rail, road and maritime accidents generally involve fast moving vehicles carrying many people or large quantities of goods and substances that can cause direct or indirect damage to the public and environment surrounding the site of the accident.
• The effects of these accidents are multiplied when several of the same or different types of vehicles are involved, or when vehicles hit buildings sheltering people or containing substances that are dangerous to humans and to the environment.

Terrorism

• Terrorism is an act of violence by humans towards other human lives with the intent of furthering political or social objectives.
• The threat of terrorism affects all communities around the world.
• Terrorists, both domestic and international, have demonstrated that they have the knowledge and capability to strike anywhere in the world.

Industrial and Technological Disasters

• Large-scale disasters from technological failures or industrial accidents.
• Affect local populations and can spread to larger areas.
• Caused by accidental leaks of water or air pollutants.
• Chemicals are toxic and carcinogenic, causing instant deaths or long-term issues like blindness and paralysis.

Fire Accidents

• Common accidents causing heavy damage to life and property.
• Loss of life is higher in crowded buildings.
• Caused by flames, cigarettes, electric sparks, or ignition sources meeting inflammable materials.
• Can be intentional (e.g., by graziers for grazing grass) or unintentional.

Safety Measures

• Pull the nearest fire alarm pull station while exiting the building.
• Check doors with your hands before opening; if hot, find another exit.
• If smoke is present, stay low to reduce inhalation.
• Once safe, call and inform authorities about the fire.
• Go to a safe area and wait for instructions from emergency personnel.

Impact of Man-made Disasters

• Humans and livestock may die or be seriously injured from fires.
• In rural areas, stored crops can burn, causing heavy losses.
• Industrial accidents put employees, nearby residents, livestock, and crops at risk from chemicals.
• Explosions, fires, or chemical leaks damage structures.
• Gaseous chemicals spread fast, causing immediate effects like dizziness, headaches, and irritation.
• Long-term effects include cancer, heart failure, brain damage, immune system issues, deformation, and congenital disorders in children.

Disaster Management

• Involves managing catastrophes like fires, floods, or earthquakes.
• Focuses on avoiding risks and handling disruptions immediately.
• Includes preparing for disasters, responding during them, and supporting recovery afterward.

Preparedness
Measures to ensure communities and services can cope with disasters:

• Community awareness and education.
• Preparing disaster management plans for communities, schools, and individuals.
• Conducting mock drills, training, and practice.
• Setting up proper warning systems.
• Arranging mutual aid.
• Identifying vulnerable groups.

Response

• Actions taken before, during, or right after a disaster to reduce its impact.
• Activating emergency operation centers (control rooms).
• Deploying search and rescue teams.
• Issuing updated warnings.
• Setting up community kitchens with local groups.
• Providing temporary living spaces and toilet facilities.
• Setting up medical camps.
• Mobilizing resources.

Recovery

• Steps to rebuild physical infrastructure and restore economic and emotional well-being.
• Community awareness on health and safety measures.
• Counseling programs for those who lost loved ones.
• Restoring essential services like roads, communication, and electricity.
• Providing shelters.
• Offering financial support.
• Reconstructing new buildings.

Prevention

• Measures to eliminate or reduce the severity of disaster impacts.
• Land use planning.
• Preventing habitation in risk zones.
• Building disaster-resistant structures.
• Finding ways to reduce risks before disasters strike.
• Community awareness and education.

Government Initiatives on Disaster Management

• The Government of India set up the National Committee on Disaster Management (NCDM), chaired by the Prime Minister.
• NCDM recommendations guide the national disaster risk management program.
• The program strengthens disaster management and response mechanisms.
• The United Nations Development Programme (UNDP) supports government efforts.
• Program components include:
  • Developing state and district disaster management plans.
  • Creating disaster risk management and response plans at village/ward, Gram Panchayat, and Block/Urban Local Body levels.
  • Forming disaster management teams and committees at all levels, with adequate women’s representation.
  • Training disaster management teams and special training for women in first aid, shelter management, water sanitation, rescue, and evacuation.
  • Building capacity for cyclone and earthquake-resistant house features in disaster-prone districts.
  • Training in retrofitting and constructing technology demonstration units.
  • Integrating disaster management plans with local self-government development plans.