Q1. Richter scale is used to measure
(a) Earthquakes
(b) Ocean depth
(c) Intensity of wind
(d) Temperature of the body
(UPSC Prelims 1979)
Answer: (a) Earthquakes
Explanation: The Richter scale quantifies the magnitude of earthquakes, based on the energy released. It is a logarithmic scale, meaning each increase by one unit represents a tenfold increase in amplitude of seismic waves.
Q2. Earthquakes are caused due to
(a) Volcanic eruptions
(b) Land slides
(c) Cyclones
(d) Movement of a part of earth’s surface on account of the faulting of rocks
(UPSC Prelims 1984)
Answer: (d) Movement of a part of earth’s surface on account of the faulting of rocks
Explanation: Earthquakes result from the sudden movement of tectonic plates along fault lines. This release of energy causes ground shaking. While volcanic activity and landslides can trigger quakes, the primary cause is faulting of rocks.
Q3. Which of the following pairs is not correct?
(a) Seismograph – Earthquakes
(b) Anemometer – Speed of the wind
(c) Hygrometer – Water vapour content of the atmosphere
(d) Lactometer – Specific gravity of liquids
(UPSC Prelims 1985)
Answer: (d) Lactometer – Specific gravity of liquids
Explanation: A lactometer measures the specific gravity of milk, not general liquids. The other instruments are correctly matched with their respective measurements.
Q4. Seismic waves that vibrate perpendicular to the direction of their path
(a) Travel through the solid parts of the earth only
(b) Travel through the solid as well as other parts of the earth
(c) Spread on the surface of the earth
(d) None of the above
(UPSC Prelims 1987)
Answer: (a) Travel through the solid parts of the earth only
Explanation: These are S-waves (secondary waves), which vibrate perpendicular to their direction of travel and can only propagate through solids. They are slower than P-waves and are crucial in understanding earthquake mechanics.
