Which one of the following statements about earthquake waves is not correct?
P waves move faster and are the first to arrive at the surface.
P waves can travel through gaseous, liquid and solid materials.
Seismographs located beyond 145° from epicentre can record the arrival of P waves.
P waves have maximum area covered under its shadow zone.
Answer is Wrong!
Answer is Right!
This question was previously asked in
UPSC NDA-2 – 2022
A) P waves (Primary waves) are the fastest seismic waves and are the first to reach any point on the Earth’s surface or within it. This statement is correct.
B) P waves are compressional waves and can travel through solid, liquid, and gaseous mediums. This statement is correct.
C) Seismographs located beyond 145° from the epicenter *can* record P waves, but these are the P waves that have been refracted by the Earth’s core. There is a P-wave shadow zone between approximately 105° and 145° where direct P waves are not recorded due to refraction. Beyond 145°, refracted P waves arrive. This statement is correct.
D) The shadow zone for P waves is the area between ~105° and ~145°. S waves (Secondary waves) cannot travel through the liquid outer core, resulting in an S-wave shadow zone that starts at ~105° and extends to the entire hemisphere beyond that. Therefore, the S-wave shadow zone is much larger than the P-wave shadow zone. This statement is incorrect.