Earthquakes and Volcanoes

Total Questions: 22

1. What is the range of the intensity scale used in measuring earthquakes? [S.S.C. Online CHSL (T-I) 12.10.2020 (Shift-I)]

(a) 1 to 15
(b) 1 to 51
(c) 1 to 7
(d) 1 to 12

Correct Answer: (d) 1 to 12

Solution:The intensity scale used to measure earthquakes range from of 1 to 12. The Modified Mercalli Intensity Scale ranges from I to XII.

2. What was the magnitude of the Indian Ocean Tsunami 2004? [S.S.C. Online CHSL (T-I) 12.10.2020 (Shift-II)]

(a) 8.6
(b) 7.4
(c) 9.1
(d) 8.9

Correct Answer: (c) 9.1

Solution:The magnitude of the Indian Ocean Tsunami in the year 2004 was 9.1.

This tsunami came on 26 December. Due to this, more than 2.5 lakh people died.

The tsunami resulted in heavy destruction, with waves up to 30 meters along the coasts of Indonesia, Sri Lanka, South India, Thailand and other countries adjacent to the Indian Ocean.

3. Which of the following is an example of the most explosive type of volcano? [SS.C. Online CHSL (T-I) 13.10.2020 (Shift-II)]

(a) Flood basalt volcanoes
(b) Cinder cones volcanoes
(c) Calderas volcanoes
(d) Shield volcanoes

Correct Answer: (c) Calderas volcanoes

Solution:Caldera volcanoes are the most explosive volcanoes found on Earth.

Usually, they are so explosive that they tend to sink down on their own instead of building a tall structure. The submerged demolition pits (pits formed by the fall of lava) are called volcanoes.

4. Which of the following gases is consistently seen to be most abundant in a volcanic eruption? [S.S.C. Online C.G.L. (T-I) 6 2020 (Shift-I)]

(a) Water Vapour
(b) Sulphur Dioxide
(c) Carbon Dioxide
(d) Hydrogen Sulphide

Correct Answer: (a) Water Vapour

Solution:

The gas most abundantly released during a volcanic eruption is water vapor (H₂O).

Common Gases in Volcanic Eruptions (in order of abundance):

Gas	Chemical Formula	Approx. % in Eruption
Water Vapor	H₂O	60–90%
Carbon Dioxide	CO₂	5–15%
Sulfur Dioxide	SO₂	1–5%
Hydrogen Sulfide	H₂S	<1%
Other Gases	(e.g., HCl, HF, CO)	Trace amounts

5. Which of the following is NOT an outcome of endogenic forces? [S.S.C. Online CGL (T-I) 13.88.2021 (Shift-III)]

(a) Sea waves
(b) Earthquakes
(c) Volcanic eruptions
(d) Landslides

Correct Answer: (a) Sea waves

Solution:Sea waves are usually generated by the exposure of surface air to sea water.

These waves are not the result of internal forces within the ocean. If an earthquake occurs at the bottom of the sea, it must be in the form of a tsunami.

Substantial energy waves are produced.

6. An elastic wave generated by an impulse such as an earthquake or an explosion is called __ . [S.S.C. Online CGL (T-I) 13.08.2021 (Shift-II)]

(a) epicentre
(b) seismic wave
(c) sound wave
(d) tectonic shift

Correct Answer: (b) seismic wave

Solution:An elastic wave produced by an impulse such as an earthquake or explosion is called a seismic wave.

Seismic waves are energy waves caused by earthquakes and volcanoes.

They arise as a result of explosions and man-made explosions.

7. Which of the following is one of the main causes of tides? [S.S.C. Online CGL (T-I) 17.08.2021 (Shift-I)]

(a) Closed orbits of planets
(b) Rotation of Earth
(c) Gravitational pull of the Sun and the Moon
(d) Solar flares

Correct Answer: (c) Gravitational pull of the Sun and the Moon

Solution:The action of the mutual gravitational force of the Moon and the Sun is the main reason for the origin of the tides.

The rise of sea water to move forward is called tide and the fallback after falling is called ebb current.

8. Which of the following is NOT an effect of an earthquake? [S.S.C. Online CHSL (T-I) 19.04.2021 (Shift-III)]

(a) Soil liquefaction
(b) Tsunami
(c) Avalanche
(d) Heavy rainfall

Correct Answer: (d) Heavy rainfall

Solution:Soil liquefaction, tsunamis and avalanches are caused by the effects of earthquakes.

In comparison, heavy rainfall occurs due to humidity, temperature and activity of disturbances.

9. _______________ are built up by the liquid and solid rock erupting from the earth's interior. [S.S.C. Online C.H.S.L. (T-I) 19.04.2021 (Shift-II)]

(a) Plateaus
(b) Fault-block mountains
(c) Erosional mountains
(d) Volcanoes

Correct Answer: (d) Volcanoes

Solution:Volcanoes are built up by the liquid and solid rock erupting from the Earth's interior.

10. Which law explains about the tides due to the moon and the sun? [S.S.C. Online MTS (T-I) 20.10.2021 (Shift-III)]

(a) Law of reflection
(b) Law of gravitation
(c) Law of inertia
(d) Law of refraction

Correct Answer: (b) Law of gravitation

Solution:The universal law of gravitation explains the Tides arising due to the Moon and the Sun.

How It Explains Tides:

The gravitational pull of the Moon (and to a lesser extent, the Sun) attracts water on Earth.
This causes bulges in the ocean — one on the side facing the Moon and one on the opposite side.
As Earth rotates, these bulges create high and low tides.

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