Natural Disasters

A natural disaster is a catastrophic event caused by natural processes of the Earth that results in significant loss of life, property, and environmental resources.

It occurs when a hazard (potentially damaging physical event) interacts with a vulnerable population and leads to disruption of normal life.
Key terms:
- Hazard → A potential natural event (e.g., cyclone, earthquake).
- Disaster → When the hazard causes widespread damage due to vulnerability.
- Risk → Probability of harmful consequences from interaction of hazard and vulnerability.
- Vulnerability → Degree to which a community or system is exposed and unable to cope with the hazard.
- Resilience → Ability of a system or society to recover from the disaster impact.

👉 Example: An earthquake in an uninhabited desert is a hazard, but not a disaster unless people or infrastructure are affected.

Types

Natural disasters can be classified into geophysical, hydrological, meteorological, climatological, biological, and extraterrestrial categories.

A. Geophysical Disasters (Earth-originated processes)

Earthquakes
- Sudden release of energy along a fault line due to tectonic plate movement.
- Measured using Richter Scale (magnitude) and Mercalli Intensity Scale (impact).
- Example: 2001 Bhuj Earthquake (India).
Volcanic Eruptions
- Emission of magma, gases, and ash through the crust.
- Types: Effusive (lava flow) and Explosive (pyroclastic flow).
- Example: Mount Vesuvius (Italy), Mount St. Helens (USA).
Tsunami
- Series of giant ocean waves triggered by undersea earthquakes, volcanic eruptions, or landslides.
- Example: 2004 Indian Ocean Tsunami.

B. Hydrological Disasters (Water-related)

Floods
- Overflow of water onto normally dry land.
- Types: Riverine floods, flash floods, coastal floods.
- Example: 2018 Kerala Floods.
Landslides
- Downward movement of soil, rock, and debris along slopes under gravity.
- Triggered by rainfall, earthquakes, deforestation.
- Example: Wayanad landslides (2024).

C. Meteorological Disasters (Atmospheric processes)

Cyclones / Hurricanes / Typhoons
- Intense low-pressure systems over tropical oceans with spiraling winds and heavy rainfall.
- Known as: Cyclone (Indian Ocean), Hurricane (Atlantic), Typhoon (Pacific).
- Example: Cyclone Amphan (2020, India).
Storms and Tornadoes
- Violent winds, often localized, with rotational movement.
- Tornado intensity measured by the Enhanced Fujita Scale (EF-Scale).

D. Climatological Disasters (Long-term weather patterns)

Droughts
- Prolonged shortage of water due to below-average rainfall.
- Types: Meteorological, Hydrological, Agricultural, and Socio-economic drought.
- Example: Marathwada droughts, Maharashtra.
Wildfires (Forest Fires)
- Uncontrolled burning of vegetation due to heat, drought, or human negligence.
- Example: Amazon Rainforest fires, California wildfires.

E. Biological Disasters

Caused by exposure to pathogens or vectors.
Examples:
- Epidemics (Cholera, Malaria).
- Pandemics (COVID-19).
- Insect infestations (Locust swarms in East Africa, 2020).

F. Extraterrestrial Disasters

Rare, caused by cosmic events.
Examples:
- Meteorite impacts (Chicxulub impact that caused dinosaur extinction ~65 million years ago).
- Solar flares (geomagnetic storms affecting satellites and power grids).

3. Key Facts

According to UNDRR (United Nations Office for Disaster Risk Reduction), global disasters have increased due to climate change, urbanization, and population density.
India is one of the most disaster-prone countries:
- 60% area prone to earthquakes,
- 12% land to floods,
- 8% to cyclones,
- 15% to droughts.

A natural disaster is the result of interaction between a natural hazard and human vulnerability. They can be geophysical, hydrological, meteorological, climatological, biological, or extraterrestrial in nature, with varying impacts on society, economy, and environment. Understanding these types with their causes, characteristics, and examples is essential for risk assessment, mitigation, and disaster management.

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