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All questions of Natural Hazards & Disasters for UPSC CSE Exam
Consider the following statements:Assertion (A): The structure of Earth can be understood by observing the passage of earthquake waves through different layers of earth.Reason (R): Some type of earthquake waves do not travel through liquid material in Earth’s layers.Which of the above statements is/are correct? - a)A is correct, and R is an appropriate explanation of A.
- b)A is correct, but R is not an appropriate explanation of A.
- c)A is correct, but R is incorrect.
- d)Both A and R are incorrect.
Correct answer is option 'A'. Can you explain this answer?
Consider the following statements:
Assertion (A): The structure of Earth can be understood by observing the passage of earthquake waves through different layers of earth.
Reason (R): Some type of earthquake waves do not travel through liquid material in Earth’s layers.
Which of the above statements is/are correct?
a)
A is correct, and R is an appropriate explanation of A.
b)
A is correct, but R is not an appropriate explanation of A.
c)
A is correct, but R is incorrect.
d)
Both A and R are incorrect.
 | Ananya Deshmukh answered |
- There are two types of body waves generated during an earthquake. They are called P- and S-waves.
- An important fact about S-waves is that they can travel only through solid materials. This characteristic of the S-waves is quite important as it has helped scientists to understand the structure of the interior of the Earth.
Consider the following statements concerning earthquake waves:1. Body waves are generated due to the release of energy at the focus and move in all directions travelling through the body of the Earth.2. The body waves interact with the surface rocks and generate a new set of waves called surface waves.3. The denser the material, the lower is the velocity of these waves.Which of the above statements is/are correct? - a)1 and 3 only
- b)2 and 3 only
- c)1 and 2 only
- d)All of the above
Correct answer is option 'C'. Can you explain this answer?
Consider the following statements concerning earthquake waves:
1. Body waves are generated due to the release of energy at the focus and move in all directions travelling through the body of the Earth.
2. The body waves interact with the surface rocks and generate a new set of waves called surface waves.
3. The denser the material, the lower is the velocity of these waves.
Which of the above statements is/are correct?
a)
1 and 3 only
b)
2 and 3 only
c)
1 and 2 only
d)
All of the above
 | Ojasvi Mehta answered |
- The two types of earthquakes are body waves and surface waves. Waves that are generated from the release of energy at the focus travel through the body by moving in all directions. Hence, it is named body waves.
- Interaction between body waves and the rock’s surface generates a new set of waves. This is called surface waves. These waves move along the surface. Because these waves travel through materials that have different densities, the velocity changes.
- The density of the material is directly proportional to the velocity, that is, if the material is denser, the velocity is higher. There is a change in direction of the waves when they get reflected or refracted by materials with different densities.
Earthquakes are most prone to occur in areas where1. There are active volcanoes.2. There are large reservoirs.3. There are tectonic fault planes.Choose the correct answer using the codes below:- a)1 and 2 only
- b)2 and 3 only
- c)All of the above
- d)1 and 3 only
Correct answer is option 'D'. Can you explain this answer?
Earthquakes are most prone to occur in areas where
1. There are active volcanoes.
2. There are large reservoirs.
3. There are tectonic fault planes.
Choose the correct answer using the codes below:
a)
1 and 2 only
b)
2 and 3 only
c)
All of the above
d)
1 and 3 only
| | Ojasvi Mehta answered |
Sources of earthquakes
- Tectonic earthquakes - sliding of plates along a fault plane.
- Volcanic earthquakes - Collapse of roofs of underground mines.
Explosions of chemicals like nuclear weapons, reservoir-induced earthquakes in areas where large reservoirs (e.g. Latur reservoir caused minor earthquake) are located.
Regarding seismic waves, consider the following statements:(a) P wave or primary wave is the fastest kind of seismic wave and, consequently, the first to ‘arrive’ at a seismic station.(b) S wave or secondary wave can only move through solid rock, not through any liquid medium.Which of the above statements is/are correct? - a)1 only
- b)2 only
- c)Both 1 and 2
- d)None of the above
Correct answer is option 'C'. Can you explain this answer?
Regarding seismic waves, consider the following statements:
(a) P wave or primary wave is the fastest kind of seismic wave and, consequently, the first to ‘arrive’ at a seismic station.
(b) S wave or secondary wave can only move through solid rock, not through any liquid medium.
Which of the above statements is/are correct?
a)
1 only
b)
2 only
c)
Both 1 and 2
d)
None of the above
| | Ojasvi Mehta answered |
- The first kind of body wave is the P wave or primary wave. This is the fastest kind of seismic wave, and, consequently, the first to ‘arrive’ at a seismic station. The P wave can move through solid rock and fluids, like water or the liquid layers of the Earth.
- The second type of body wave is the S wave or secondary wave, which is the second wave you feel in an earthquake. An S wave is slower than a P wave and can only move through solid rock, not through any liquid medium.
Consider the following statements:Assertion (A): Shallow-focus earthquakes may occur along transform boundaries.Reason (R): Significant energy may be released where crustal plates slide past one another.Which of the above statements is/are correct? - a)A is correct, and R is an appropriate explanation of A.
- b)A is correct, but R is not an appropriate explanation of A.
- c)A is correct, but R is incorrect.
- d)Both A and R are incorrect.
Correct answer is option 'A'. Can you explain this answer?
Consider the following statements:
Assertion (A): Shallow-focus earthquakes may occur along transform boundaries.
Reason (R): Significant energy may be released where crustal plates slide past one another.
Which of the above statements is/are correct?
a)
A is correct, and R is an appropriate explanation of A.
b)
A is correct, but R is not an appropriate explanation of A.
c)
A is correct, but R is incorrect.
d)
Both A and R are incorrect.
| | Ojasvi Mehta answered |
There are three types of plate boundaries: spreading zones, transform faults and subduction zones.
• Earthquakes are located along the normal faults that form the sides of the rift or beneath the floor of the rift.
• However, transform faults are found where plates slide past one another. Shallow-focus earthquakes occur along transform boundaries where two plates move past each other.
Earthquakes occur at1. Divergent plate boundaries.2. Ocean-ocean convergent plate boundaries.3. Ocean-continent plate boundaries.4. Transform boundaries.Which of the above statements is/are correct? - a)1, 3 and 4 only
- b)1, 2 and 4 only
- c)1 and 3 only
- d)All of the above
Correct answer is option 'D'. Can you explain this answer?
Earthquakes occur at
1. Divergent plate boundaries.
2. Ocean-ocean convergent plate boundaries.
3. Ocean-continent plate boundaries.
4. Transform boundaries.
Which of the above statements is/are correct?
a)
1, 3 and 4 only
b)
1, 2 and 4 only
c)
1 and 3 only
d)
All of the above
| | Ojasvi Mehta answered |
- The boundaries where the plates meet experience most earthquakes. Locations of earthquakes and the kinds of ruptures they produce serve as a great source of information to scientists to define the plate boundaries. The three types of plate boundaries are spreading zones, transform faults and subduction zones. At spreading zones, molten rock rises, which pushes two plates apart and adds new material at their corners.
- Divergent boundaries are those at which crustal plates move away from each other, such as at mid-oceanic ridges.
- The formation of a new ocean crust that is pushed away from both sides of the ridge fault creates a tension setting that results in the formation of the graben. Earthquakes arc located along the normal faults that form the sides of the rift or beneath the floor of the rift.
- Transform faults are found where plates slide past one another. Shallow-focus earthquakes occur along transform boundaries where two plates move past each other.
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