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Q10 (NDA-II/2022) Science & Technology › Basic Science (Physics, Chemistry, Biology) › Waves and acoustics

Which one of the following statements about earthake waves is not correct?

Result
Your answer:  ·  Correct: D
Explanation

P-waves (Primary waves) are the fastest seismic waves and are the first to arrive at the surface [1][2]. They are longitudinal waves capable of traveling through solid, liquid, and gaseous materials [2]. Seismographs located beyond 142° to 145° from the epicenter can record P-waves after they have been refracted by the Earth's core [1][3]. However, statement 4 is incorrect because P-waves do not have the maximum shadow zone area. The P-wave shadow zone is a relatively narrow band located between approximately 103° and 142° from the epicenter [1][3]. In contrast, S-waves (Secondary waves) cannot pass through the liquid outer core at all, resulting in a much larger shadow zone that covers the entire area beyond 103° from the epicenter. Therefore, the S-wave shadow zone is significantly more extensive than that of the P-wave.

Sources

  1. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 5: Earths Magnetic Field (Geomagnetic Field) > Shadow Zone For Both P Wave and S Wave > p. 64
  2. [2] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 4: Earths Interior > Primary Waves (P-Waves) > p. 60
  3. [3] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 4: Earths Interior > P Wave Shadow Zone > p. 63
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