EARTH SCIENCE
EARTHQUAKES
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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7 minutes 20 seconds
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11 minutes 20 seconds
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4 minutes
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5 minutes
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Detailed explanation-1: -There are two types of seismic waves, primary waves and secondary waves. Primary waves, also known as P waves or pressure waves, are longitudinal compression waves similar to the motion of a slinky (SF Fig. 7.1 A). Secondary waves, or S waves, are slower than P waves.
Detailed explanation-2: -With increasing distance from the earthquake the time difference between the arrival of the P waves and the arrival of the S waves increases.
Detailed explanation-3: -The P waves are easy to identify because they are always first to arrive and their amplitude is smaller than the S wave. S waves are indicated by an abrupt change in wave amplitude. In the seismogram below, we see that the S wave arrived at about 34 sec after the P wave arrived.
Detailed explanation-4: -P and S waves from an earthquake travel at different speeds, and this difference helps locate the earthquake “epicenter” (where the disturbance took place).