UPSC Prelims 2001 · General Studies
Question 59: Geography
Consider the following statements regarding earthquakes: I. The intensity of an earthquake is measured on the Mercalli scale. II. The magnitude of an earthquake is a measure of energy released. III. Earthquake magnitudes are based on direct measurements of the amplitude of seismic waves. IV. In the Richter scale, each whole number demonstrates a hundred-fold increase in the amount of energy released. Which of these statements are correct?
AnswerThe answer is (a).
Statements I, II and III are correct. Intensity is measured on the Mercalli scale (effects felt at a place), while magnitude is based on the amplitude of seismic waves recorded by instruments and relates to the energy released. Statement IV is wrong: each whole number on the Richter scale means ten times the amplitude and roughly 32 times the energy, not a hundred times.
- I. Intensity is measured on the Mercalli scale.
- II. Magnitude is a measure of the energy released.
- III. Magnitude is derived from the amplitude of seismic waves.
- IV. One Richter unit is about 32 times the energy, not 100 times.
Why each option is right or wrong
- (a) Right: I, II and III.
- (b) IV is wrong and I is left out.
- (c) IV is wrong and II and III are left out.
- (d) II is also correct.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2001, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.