Question

In the asthenosphere, the velocity of S-waves in partly molten rocks:
A. Increases
B. Decreases
C. Remain Constant
D. First increases then decreases
Choose the correct answer from the options given below:

• (A) only
• (B) only
• (C) only
• (D) only

Hint:

S-waves cannot propagate through fully molten regions, and their reduced velocity in the asthenosphere is a key indicator of partial melting.

Answer 1

The Correct Option is B

Partially molten rocks in the asthenosphere reduce its rigidity, causing S-wave velocity to decrease. This identifies the asthenosphere as a mechanically weak layer in the Earth’s upper mantle.