NCERT Class 11 Geography — Chapter 2: Interior of the earth

mcqeasy

The magnitude of an earthquake, as measured by the Richter scale, indicates:

Official previous-year question

Verified 1 Aug 2026.

Options

AThe distance of the epicentre from the observer.
BThe depth of the focus of the earthquake.
CThe visible damage caused by the event.
DThe energy released during the quake.

Did you get this right?

Solution

The correct option is The energy released during the quake.

Explanation

The measurement of earthquakes is primarily conducted using two distinct parameters: Magn and Intensity. While these terms are often used interchangeably in general conversation, they represent fundamentally different scientific concepts in seismology.

Option Analysis

The visible damage caused by the event. is Incorrect: The visible damage caused by an event refers to the Intensity of the earthquake. Intensity is a qualitative measure of the shaking felt and the destruction caused at a specific location. It is measured by the Modified Mercalli Scale, not the Richter scale.
The depth of the focus of the earthquake. is Incorrect: The depth of the focus (hypocenter) refers to the vertical distance from the Earth's surface to the point where the rupture originated. While depth influences the severity of surface shaking, it is a spatial coordinate and not what the Richter scale measures.
The energy released during the quake. is Correct: The Richter scale is used to measure the Magn of an earthquake. Magnitude is a quantitative measure of the total energy released at the earthquake's source. It is determined logarithmically based on the amplitude of seismic waves recorded by seismographs. Unlike intensity, the magnitude of a specific earthquake is a single value that does not vary with distance from the epicenter.
The distance of the epicentre from the observer. is Incorrect: The distance of the epicenter from the observer is a geographical measurement. While the distance affects the intensity (how much shaking is felt), it does not define the magnitude.

Key Takeaway

Magn (measured by the Richter Scale) quantifies the energy released during an earthquake, whereas Intensity (measured by the Mercalli Scale) assesses the visible damage and human perception of shaking.

Your note

More from Chapter 2: Interior of the earth

With reference to 'Body Waves', consider the following statements: 1. They are generated due to the release of energy at the focus. 2. They move only in a vertical direction towards the surface. 3. They interact with surface rocks to generate surface waves. Which of the statements given above is/are correct?

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Which of the following statements is correct regarding the 'Shadow Zone' of P-waves?

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With reference to the 'Mantle', consider the following statements: 1. The lower mantle is in a liquid state. 2. It extends from Moho's discontinuity to a depth of 2,900 km. 3. It has a lower density than that of the crust. Which of the statements given above is/are correct?

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Consider the following statements regarding the 'Crust': 1. It is the innermost solid part of the earth. 2. It is brittle in nature. 3. Its thickness varies between oceanic and continental areas. Which of the statements given above is/are correct?

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With reference to the sources of information about the interior of the earth, consider the following statements: 1. Mining and drilling projects provide direct information about the earth's interior materials. 2. Meteors are considered a direct source of information because they originate from the earth's core. 3. Gravitation and magnetic fields are indirect sources of information. Which of the statements given above is/are correct?

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The correct option is The energy released during the quake.

Explanation

Option Analysis

The visible damage caused by the event. is Incorrect: The visible damage caused by an event refers to the Intensity of the earthquake. Intensity is a qualitative measure of the shaking felt and the destruction caused at a specific location. It is measured by the Modified Mercalli Scale, not the Richter scale.
The depth of the focus of the earthquake. is Incorrect: The depth of the focus (hypocenter) refers to the vertical distance from the Earth's surface to the point where the rupture originated. While depth influences the severity of surface shaking, it is a spatial coordinate and not what the Richter scale measures.
The energy released during the quake. is Correct: The Richter scale is used to measure the Magn of an earthquake. Magnitude is a quantitative measure of the total energy released at the earthquake's source. It is determined logarithmically based on the amplitude of seismic waves recorded by seismographs. Unlike intensity, the magnitude of a specific earthquake is a single value that does not vary with distance from the epicenter.
The distance of the epicentre from the observer. is Incorrect: The distance of the epicenter from the observer is a geographical measurement. While the distance affects the intensity (how much shaking is felt), it does not define the magnitude.