With reference to Earth's vibrations, consider the following: 1. They travel only in a straight line. 2. They are produced when Lithospheric plates move. 3. The strength of the vibration decreases as it moves away from the epicentre. Which of the statements given above is/are correct?

The correct option is (c) 2 and 3 only. Explanation Earthquakes are vibrations of the Earth produced by the sudden release of energy in the Earth's lithosphere, which generates seismic waves that travel in all directions. Statement-wise Analysis: - Statement 1 is Incorrect: Seismic waves do not travel in straight lines. As they propagate through the Earth's interior, they encounter layers with varying densities and physical properties. This variation causes the waves to refract (bend) and reflect, resulting in curved paths rather than straight lines. - Statement 2 is Correct: The primary cause of earthquakes is the movement of lithospheric plates. The release of energy usually occurs along a fault line where rocks slip past each other due to tectonic forces. This sudden movement generates the vibrations known as earthquakes. - Statement 3 is Correct: The energy of seismic waves dissipates as they travel through the Earth. Consequently, the strength (intensity) of the vibration is highest at the epicentre and decreases as the distance from the epicentre increases due to geometrical spreading and attenuation. Key Takeaway: Seismic waves follow curved paths due to refraction caused by density variations in the Earth's interior, and their intensity diminishes with distance from the epicentre.

With reference to Earth's vibrations,… - NCERT Class 7 Geography MCQ

NCERT Class 7 Geography — Chapter 2: Our Changing Earth

mcqmedium

With reference to Earth's vibrations, consider the following:

They travel only in a straight line.
They are produced when Lithospheric plates move.
The strength of the vibration decreases as it moves away from the epicentre.

Which of the statements given above is/are correct?

NCERT textbook question

From NCERT The Earth Our Habitat · Page 13

Options

A1 and 2 only
B2 only
C2 and 3 only
D1, 2 and 3

Did you get this right?

Solution

The correct option is (c) 2 and 3 only.

Explanation

Earthquakes are vibrations of the Earth produced by the sudden release of energy in the Earth's lithosphere, which generates seismic waves that travel in all directions.

Statement-wise Analysis:

Statement 1 is Incorrect: Seismic waves do not travel in straight lines. As they propagate through the Earth's interior, they encounter layers with varying densities and physical properties. This variation causes the waves to refract (bend) and reflect, resulting in curved paths rather than straight lines.
Statement 2 is Correct: The primary cause of earthquakes is the movement of lithospheric plates. The release of energy usually occurs along a fault line where rocks slip past each other due to tectonic forces. This sudden movement generates the vibrations known as earthquakes.
Statement 3 is Correct: The energy of seismic waves dissipates as they travel through the Earth. Consequently, the strength (intensity) of the vibration is highest at the epicentre and decreases as the distance from the epicentre increases due to geometrical spreading and attenuation.

Key Takeaway:

Seismic waves follow curved paths due to refraction caused by density variations in the Earth's interior, and their intensity diminishes with distance from the epicentre.

Your note

More from Chapter 2: Our Changing Earth

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As the river enters the plain, it twists and turns forming large bends known as:

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What causes the movement of Lithospheric plates?

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With reference to Earthquakes, consider the following statements: 1. The place in the crust where the movement starts is called the focus. 2. The place on the surface above the focus is called the focus. 3. Vibrations travel outwards from the epicentre as waves. Which of the statements given above is/are correct?

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The material carried by the glacier such as rocks, sand, and silt gets deposited to form:

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