![]() It extends from 105 to 142 degrees.Ī region of low sound intensity that sound waves traveling away from a source in the ocean do not reach, usually because the sound waves are refracted away from that region. The P-wave shadow zone is the result of the refraction effects P-waves go through as they travel deep inside the Earth. What causes a shadow zone quizlet?Ĭompressional waves (P waves) travel through the outer core while shear waves (S waves) can not. This is because P-waves are refracted when they pass through the transition between the semisolid mantle and the liquid outer core. The shadow zone of P-waves appears as a band around the earth between 103° and 142° away from the epicentre. 5 How old is the oldest water in the ocean?.The shadow zone of S-waves is not only larger in extent but it is also a little over 40 per cent of the earth surface. The shadow zone of P-waves appears as a band around the earth between 105° and 145° away from the epicentre.The shadow zone of S-wave is much larger than that of the P-waves.The entire zone beyond 105° does not receive S-waves.Thus, a zone between 105° and 145° from epicentre was identified as the shadow zone for both the types of waves.However, the seismographs located beyond 145° from epicentre record the arrival of P-waves, but not that of S-waves. It was observed that seismographs located at any distance within 105° from the epicentre, recorded the arrival of both P and S-waves. Figure 6 shows the shadow zones of P and S-waves.The study of different events reveals that for each earthquake, there exists an altogether different shadow zone. There exist some specific areas where the waves are not reported by seismograph.Surface waves are considered to be the most damaging waves. Hence, they create troughs and crests in the material through which they pass. The direction of vibrations of S-waves is perpendicular to the wave direction in the vertical plane.It has helped scientists to understand the structure of the interior of the earth. This characteristic of the S-waves is quite important. They can travel only through solid materials. ![]()
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