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Q58
(NDA-I/2023)
Geography › World Physical Geography
Official Key
Which of the following statements is/are correct ? 1. Hypocenter is the point on the surface of the Earth, nearest to the focus. 2. Velocity of earthquake waves is higher in denser materials. 3. P waves move faster and are the first to arrive at the surface of the Earth. Select the correct answer using the code given below :
Explanation
The correct answer is Option B (2 and 3) based on the following geographical principles:
- Statement 1 is incorrect: The hypocenter (or focus) is the actual point within the Earth where the earthquake originates. The point on the Earth's surface directly above the hypocenter is called the epicenter.
- Statement 2 is correct: The velocity of seismic waves is directly proportional to the density and elasticity of the medium. As waves travel deeper into the Earth's interior where materials are denser, their velocity generally increases.
- Statement 3 is correct: P-waves (Primary waves) are longitudinal waves that travel faster than S-waves and surface waves. Because of their high speed, they are the first seismic waves to reach the surface and be recorded by seismographs.
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