Tag: seismic waves and tsunami

Questions Related to seismic waves and tsunami

Assertion : An earthquake will not cause uniform damage to all building in an affected area, even if they are built with the same strength and materials.
Reason : The one with its natural frequency close to the frequency of seismic wave is likely to be damaged less.

physics structure of earth seismic waves and tsunami causes of earthquakes origin of earth and its internal energy transfer of charge lightning safety

  1. If both assertion and reason are true and reason is the correct explanation of assertion.

  2. If both assertion and reason are true and reason is not the correct explanation of assertion.

  3. If assertion is true but reason is false.

  4. If both assertion and reason are false.

Show answer
Correct Option: C
Explanation:

An earth quake will not cause uniform damage to all building in an affected area because the natural frequencies of a building depend on its height and other size parameters and the nature of building materials.
The one with its natural frequency close to the frequency of seismic wave is likely to be damaged more.

An earthquake generates both transverse $(S)$ and longitudinal $(P)$ sound waves in the earth. The speed of $S$ waves is about $4 \,\,km \,\,s^{-1}$ and that of $P$ waves is about $8 \,\,km \,\,s^{-1}$. A seismograph records $P$ and $S$ waves from an earthquake.The first $P$ wave arrives $4$ min before the first $S$ wave. The epicentre of the earthquake is located at a distance of about

physics structure of earth seismic waves and tsunami causes of earthquakes origin of earth and its internal energy transfer of charge lightning safety

  1. $192 km$

  2. $384 km$

  3. $1920 km$

  4. $3840 km$

Show answer
Correct Option: C
Explanation:
Let $\nu _1, \nu _2$ be speed $S$ of $S$ and $P$ waves and $t _1,t _2$ be the time taken by these waves to travel to reach the seismograph. Let the epicenter of the earthquake is located at a distance $d$ from the seismograph. Then,
$d = V _1 t _1 = V _2 t _2$          ................ .....(i)
Here, $V _1 = 4 km \,\,s^{-1}$ and $V _2 = 8 km \,\,s^{-1}$
$\therefore 4t _1 = 8t _2 \Longrightarrow t _1 = 2t _2$           ....(ii)
and  $t _1 - t _2 = 4 min = 240 s$
$\therefore 2t _2 - t _2 = 240$      ....................  [using (ii)]
or $t _2 = 240 s$
put in Eq. (ii), we get,
$t _1 = 2 \times 240 s = 480 s$
From Eq. (i), we get, $d = (4 km \,\,s^{-1}) (480 s) = 1920 km$

The weak zone around the boundaries of plates underneath the Earth, which is prone to slide and cause an earthquake is commonly known as :

physics structure of earth seismic waves and tsunami causes of earthquakes origin of earth and its internal energy transfer of charge lightning safety

  1. Fault zone

  2. Eruption zone

  3. Explosive zone

  4. Sliding zone

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Correct Option: A
Explanation:

The weak zone around the boundaries of plates underneath the Earth, which  is prone to slide and cause an earthquake is known as Seismic or Fault Zones.

The correct option is A.

Seismic waves is recorded by an instrument called seismograph.

physics structure of earth seismic waves and tsunami causes of earthquakes origin of earth and its internal energy transfer of charge lightning safety

  1. True

  2. False

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Correct Option: A

The natural calamity that cannot be predicted accurately in advance:

physics structure of earth seismic waves and tsunami causes of earthquakes origin of earth and its internal energy transfer of charge lightning safety

  1. Flood

  2. Cyclone

  3. Earthquake

  4. Famine

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Correct Option: C

Which of the following country in the world is most prone to earthquake?

physics structure of earth seismic waves and tsunami causes of earthquakes origin of earth and its internal energy transfer of charge lightning safety

  1. India

  2. America

  3. China

  4. Japan

Show answer
Correct Option: D
Explanation:

Japan is the country in the world is most prone to earthquake.

Waves produced during in earthquake are _____waves. .

physics structure of earth seismic waves and tsunami causes of earthquakes origin of earth and its internal energy transfer of charge lightning safety

  1. ultrasonic

  2. infrasonic

  3. audible

  4. both (1) and (2)

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Correct Option: B

The point where the waves originate is called the _______ of the earthquake

physics structure of earth seismic waves and tsunami causes of earthquakes origin of earth and its internal energy transfer of charge lightning safety

  1. centre

  2. epicenter

  3. focus

  4. origin

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Correct Option: C
Explanation:

Answer is C.

The point where the waves originate is called the focus of the earthquake.
The point within the earth along the rupturing geological fault where an earthquake originates is called the focus, or hypocenter. The point on the earth's surface directly above the focus is called the epicenter. Earthquake waves begin to radiate out from the focus and subsequently form along the fault rupture. If the focus is near the surface between 0 and 70 km (0 and 40 mi) deepshallow-focus earthquakes are produced. If it is intermediate or deep below the crust between 70 and 700 km (40 and 400 mi) deepa deep-focus earthquake will be produced. Shallow-focus earthquakes tend to be larger, and therefore more damaging, earthquakes. This is because they are closer to the surface where the rocks are stronger and build up more strain.

In which of the following states of India, earthquake is most likely to occur?

physics structure of earth seismic waves and tsunami causes of earthquakes origin of earth and its internal energy transfer of charge lightning safety

  1. Gujarat

  2. Chhattisgarh

  3. Tamil Nadu

  4. Kerala

Show answer
Correct Option: A
Explanation:

In India, the seismic or fault zores lie below Kashmir, Western and Central Himalays, North-East, Runn of Kutch and Indo-gangetic plane. So, among the options provided, earthquake is most likely to occur in Gujarat.

An earthquake is caused by

physics structure of earth seismic waves and tsunami causes of earthquakes origin of earth and its internal energy transfer of charge lightning safety

  1. shaking of the earth

  2. strain building up in the tectonic plates

  3. plates slipping along the fault lines

  4. all of the above

Show answer
Correct Option: D
Explanation:

An earthquake is caused by shaking of the earth, strain building up in the tectonic plates, plates slipping along the fault lines, etc.
Earthquake is shaking of the earth's surface caused by rapid movement of the earth's rocky outer layer. Earthquakes occur when energy stored within the earth, usually in the form of strain in rocks, suddenly releases. This energy is transmitted to the surface of the earth by earthquake waves.