# Earthquake Engineering Questions and Answers – Tsunami

This set of Earthquake Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Tsunami”.

1. What will be the velocity of a Tsunami wave of depth 175 m?
a) 41.43 Kmph
b) 30.56 Kmph
c) 56.85 Kmph
d) 37.52 Kmph

Explanation: The velocity of a Tsunami wave is given by the formula:
V = $$\sqrt {gh}$$
Here, acceleration due to gravity (g) = 9.8 m/s2, Depth of the Tsunami wave (h) = 175 metre
Therefore, V = $$\sqrt {9.81 \times 175}$$ = 41.43 Kmph.

2. What will be the depth of a Tsunami wave of velocity 35.5 km/hr.?
a) 130.42 mts
b) 128.46 mts
c) 103.65 mts
d) 111.36 mts

Explanation: The velocity of a Tsunami wave is given by the formula: V = $$\sqrt {gh}$$
Here, acceleration due to gravity (g) = 9.8 m/s2
Velocity of the Tsunami wave (V) = 35.5 Kmph
Therefore, 35.5 = $$\sqrt {9.81 \times h}$$
h = 35.52/9.81 = 128.46 mts.

3. Tsunamis are caused because of which of these phenomena?
a) Seismic activities under the sea bed
b) Gravitational pull of the moon and the earth
c) Development of a low pressure zone near the sea surface
d) Volcanic activities under the sea

Explanation: Tsunamis occur mainly because of the collision of tectonic plates at the boundaries leading to the development of a subduction zone on the ocean floor. The friction between the plate undergoing subduction and the over-riding plate results in the two plates being stuck and releasing energy in form of Tsunami waves.

4. ‘Tsunami’ is a Japanese word which means?
a) Harbour waves
b) Sea waves
c) Coastal waves
d) High tide

Explanation: Tsunami is a Japanese word which means harbour waves. The word ‘tsu’ means harbour and ‘nami’ means waves.

5. In which of these zones do Tsunami generally occur?
a) Sub-duction zone
b) Convergence zone
c) Divergence zone
d) Uplift zone

Explanation: A sub-duction zone is created when two tectonic plates collide at the boundaries. Due to the relative rigidity of one plate lesser than the other, one plate undergoes depression and the other rises above the weaker plate. Such a motion of the tectonic plates under the sea bed causes Tsunami.

6. Which of the following Tsunami event is among the deadliest Tsunamis that have occurred in the Indian Ocean?
a) Sumatra, 2004
b) Sunda Islands, 2004
c) Andaman and Nicobar Islands, 1941
d) Indonesia, 2018

Explanation: The Sumatra Tsunami which occurred on 26th December 2004 was the deadliest Tsunami to have occurred in the Indian Ocean. The death toll arising from this Tsunami was more than 2, 20,000.

7. The height of the Tsunami waves ______________ as it approaches the sea-shore.
a) Increases
b) Decreases
c) Remains same
d) Increases and then decreases

Explanation: As the tsunami approach the shoreline the wavelength of the wave is reduced and the wave energy is directed upwards. This results in an increase in the height of the waves as it approaches the sea-shore.

8. The increase in the height of the sea waves as it approaches the sea shore during a Tsunami is called as _______________
a) Run-off
b) Run-up
c) Inundation
d) High tide

Explanation: The height of the waves along the shoreline increases as a result of wave energy being directed upward, due to shortening of wavelength at the sea shore. The elevated waves are a major cause of destruction in a Tsunami. Such a phenomena of wave elevation is called run-up.

9. The phenomena in which the Tsunami wave travels a long distance inland is called as ____________
a) Inundation
b) Run-off
c) Run-up
d) High-tide

Explanation: The phenomena wherein the tsunami waves travel inland after reaching the shore line is called Tsunami inundation. It is measured in terms of the horizontal distance from the shore line and the inundation line. The damage caused by a Tsunami wave increases with an increase in the distance between the shore line and the inundation line.

10. The ability of a Tsunami to bend around and through the islands is called as ______________
a) Inundation
b) Wrap around effect
c) Run-up
d) Wobble effect

Explanation: Elevated Tsunami waves try to refract or bend around the shore line of islands. They also tend to diffract along the channels of islands. The ability of a tsunami wave to bend around and diffract through the islands is called the wrap-around effect.

Sanfoundry Global Education & Learning Series – Earthquake Engineering.

To practice all areas of Earthquake Engineering, here is complete set of Multiple Choice Questions and Answers.

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