Multiple choice

Directions: The following items consist of two statements, one labelled as Assertion (A) and the other labelled as Reason (R). You are to examine these two statements carefully and decide if the Assertion (A) and the Reason (R) are individually true and if so, whether the reason is a correct explanation of the Assertion. Select your answer to these items using the codes given below. Assertion (A) : The location of the epicenter of an earthquake may be estimated using the time-leg between the arrival of P and S waves. Reason (A) : The L wave cannot start until the P wave hits the surface.

  1. Both A and R are true and R is the correct explanation of A.

  2. Both A and R are correct but R is not the correct explanation of A.

  3. A is true but R is false.

  4. A is false but R is true.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The distance to an earthquake's epicenter is determined by the time interval between the arrival of primary (P) and secondary (S) waves. While surface waves (L-waves) are indeed generated when body waves reach the surface, this fact is a separate physical occurrence and does not explain the calculation method using P and S wave lags.

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