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NDA 1 2025 GAT, question 103

Topic: Geography

Q103

Which of the following statements with reference to L-Wave or Long Wave generated by an earthquake is/are correct ?

  1. They follow the Earth’s circumference

  2. They travel at more or less at a constant rate

Select the answer using the code given below :

  1. (a) 1 only
  2. (b) 2 only
  3. (c) Both 1 and 2Correct answer
  4. (d) Neither 1 nor 2

Solution.

Answer: (c) Both 1 and 2

  1. L-waves are surface waves that travel along the Earth's surface, following its circumference.
  2. Textbooks describe them as travelling at a more or less constant speed, slower than P and S waves.

Trap: "More or less constant" is the simplified textbook description; real surface-wave speed varies with the rock layers.