CDS Geography · Earth's Structure, Landforms and Geological Time
Natural Hazards and Disasters
How natural disasters are grouped, the kinds of drought, India's earthquake zones and what decides how much damage a quake does.
Why this matters
Seven questions, three of them from the papers of 2025 and 2026. The avalanche has been asked twice, both times as a question of which group of disaster it belongs to.
Concept 1 of 2: Kinds of natural disaster
Definition
The four groups (NCERT, India: Physical Environment):
- Atmospheric: blizzards, thunderstorms, lightning, tornadoes, tropical cyclones, drought, hailstorm, frost, heat waves and cold waves.
- Terrestrial: earthquakes, volcanic eruptions, landslides, avalanches, subsidence and soil erosion.
- Aquatic: floods, tidal waves, storm surges and tsunamis.
- Biological: plants and animals as colonisers (locusts), insect infestations, and diseases such as epidemics.
Kinds of drought:
- Meteorological drought: a long spell of too little rain, badly spread over time and place. India's weather office declares it when rain falls short of the normal by about a quarter or more.
- Agricultural drought: too little soil moisture for crops, also called soil moisture drought.
- Hydrological drought: water in rivers, lakes and the ground runs short.
- Ecological drought: the natural ecosystem suffers from water shortage.
In India, the National Disaster Management Authority (headed by the Prime Minister) and the National Institute of Disaster Management work under the Disaster Management Act, 2005. The Central Water Commission runs the country's flood forecasting stations.
| Group | Examples |
|---|---|
| Atmospheric | Cyclone, drought, hailstorm, frost, heat waveQ CDS 2025 (II): the avalanche was the one that is NOT atmospheric. |
| Terrestrial | Earthquake, volcano, landslide, avalanche |
| Aquatic | Flood, storm surge, tsunami |
| Biological | Locust swarms, insect pests, epidemics |
Practice this conceptself-check · 4 quick reps
The same idea in a real exam question:
Example 1 · Earth's Structure, Landforms and Geological Time · Natural Hazards and Disasters
Drought is atmospheric, avalanche is terrestrial
Agricultural drought is the soil moisture drought
Concept 2 of 2: Earthquake zones of India and damage
Definition
India's seismic zones:
- The map is drawn by the Bureau of Indian Standards. Its 2002 version, the one in the textbooks, runs from Zone II (lowest risk) to Zone V (highest).
- Zone V: the Himalayan belt (including Kumaon and Garhwal in Uttarakhand, such as Pithoragarh), the North-East, Kachchh in Gujarat and the Andaman and Nicobar Islands.
- The peninsular plateau is old and stable, so most of it is in the low zones. Hyderabad and Secunderabad sit in Zone II.
What decides the damage:
- The strength of the earthquake.
- How many people and buildings are in the area (population density).
- The type and quality of buildings: most deaths come from collapsing structures, not from the shaking itself.
- Climate has no bearing on the damage.
| Zone (2002 map) | Risk | Example places |
|---|---|---|
| Zone V | Very high | Pithoragarh and the Himalayan belt, North-East, Kachchh, Andaman Islands |
| Zone IV | High | Delhi, much of the Ganga plain near the Himalayas |
| Zone III | Moderate | Much of central and eastern India, including Bhubaneswar |
| Zone II | Low | Much of the Deccan plateau, including Hyderabad and Secunderabad |
Practice this conceptself-check · 3 quick reps
The same idea in a real exam question:
Example 2 · Earth's Structure, Landforms and Geological Time · Natural Hazards and Disasters
Climate does not decide earthquake damage
The Himalayan belt, not the plateau, is the danger zone
Summary — formulas & gotchas at a glance
A revision cheat-sheet for the formulas and gotchas above. Click any concept name to jump back to its full explanation.
Reference tables (2)
Kinds of natural disaster4 rows
| Group | Examples |
|---|---|
| Atmospheric | Cyclone, drought, hailstorm, frost, heat waveQ CDS 2025 (II): the avalanche was the one that is NOT atmospheric. |
| Terrestrial | Earthquake, volcano, landslide, avalanche |
| Aquatic | Flood, storm surge, tsunami |
| Biological | Locust swarms, insect pests, epidemics |
Earthquake zones of India and damage4 rows
| Zone (2002 map) | Risk | Example places |
|---|---|---|
| Zone V | Very high | Pithoragarh and the Himalayan belt, North-East, Kachchh, Andaman Islands |
| Zone IV | High | Delhi, much of the Ganga plain near the Himalayas |
| Zone III | Moderate | Much of central and eastern India, including Bhubaneswar |
| Zone II | Low | Much of the Deccan plateau, including Hyderabad and Secunderabad |
Watch out for (4)
- Drought is atmospheric, avalanche is terrestrial→ Kinds of natural disaster
- Agricultural drought is the soil moisture drought→ Kinds of natural disaster
- Climate does not decide earthquake damage→ Earthquake zones of India and damage
- The Himalayan belt, not the plateau, is the danger zone→ Earthquake zones of India and damage
Test yourself on Earth's Structure, Landforms and Geological Time
15 past CDS questions from this chapter, timed at 15 minutes and marked the way the exam marks it. You see your score and every answer the moment you finish. Free to start.