UPSC Prelims 2004 Q87: Geography – Physical Geography & Geomorphology
Consider the following geological phenomena:
1. Development of a fault
2. Movement along a fault
3. Impact produced by a volcanic eruption
4. Folding of rocks
Which of the above cause earthquakes?
- (a) 1, 2 and 3
- (b) 2 and 4
- (c) 1, 3 and 4
- (d) 1, 2, 3 and 4
Answer: (a) 1, 2 and 3
Explanation
Geological phenomena and earthquakes
| Phenomenon | Cause of earthquakes? |
|---|---|
| 1. Development of a fault | Yes |
| 2. Movement along a fault | Yes — the main cause |
| 3. Impact of a volcanic eruption | Yes — volcanic earthquakes |
| 4. Folding of rocks | No — folding is a slow process |
Fault formation, movement along a fault and volcanic impact cause earthquakes, while the slow folding of rocks does not.
Answer: (a) 1, 2 and 3.
Why each option is right or wrong
- (a) CORRECT. Phenomena 1, 2 and 3 cause earthquakes.
- (b) Incorrect. Folding is not a cause and fault movement is.
- (c) Incorrect. Folding is not a cause and fault development is.
- (d) Incorrect. Folding is a slow process, not a cause.
Key point
Earthquake causes: faulting, volcanic activity, plate movement, dams and mining.
Remember
Faults and volcanic eruptions cause earthquakes; folding does not.
Common mistakes
- Counting folding as an earthquake cause.
- Forgetting about volcanic earthquakes.
- Mixing slow and sudden crustal movements.
Exam tip
Earthquakes are sudden releases of energy along faults.
Sources
- NCERT Class XI Geography — Interior of the Earth
- United States Geological Survey — Earthquake Hazards Program: What causes earthquakes?