UPSC Prelims 2004 · General Studies
Question 87: Geography
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?
AnswerThe answer is (a).
Earthquakes come from a sudden release of strain: the development of a fault, movement along a fault, and the shock of a volcanic eruption can each cause them. Folding is a slow bending of rock that does not release energy suddenly, so it is not counted as a cause of earthquakes.
- 1. Development of a fault releases strain suddenly.
- 2. Movement along a fault is the usual source of tremors.
- 3. A volcanic eruption can send shocks through the crust.
- 4. Folding is slow bending and does not release strain suddenly.
How you could have got this
- If you were sure statement 4 is not correct, (b), (c) and (d) go: each of them includes 4.
What you needed to know: Folding is slow bending and does not release strain suddenly.
Only (a) is left. You didn’t need statements 1, 2 or 3.
This follows an unofficial answer: UPSC has not published its key for this year, and if that answer is wrong, so is this path.
Which options go is worked out from UPSC’s key and the options, not by a model.
Why each option is right or wrong
- (a) Correct: faulting, fault movement and volcanic shocks cause earthquakes.
- (b) Leaves out two causes and includes folding.
- (c) Includes folding and leaves out fault movement.
- (d) Includes folding, which is not counted as a cause.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2004, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.