Question

The given figure shows the ray path of a P-wave propagating through the Earth. Choose the CORRECT P-phase corresponding to the ray path.

• A. PcP
• B. PKP
• C. PPP
• D. PmP

Hint:

Mnemonic for seismic phases:
- \(P\): Mantle path.
- \(K\): Outer core.
- \(I\): Inner core.
Reflections add suffix \(m\) (Moho), \(c\) (core–mantle boundary).

Answer 1

The Correct Option is B

Step 1: Understanding P–wave propagation.
Seismic phases are named according to the path a wave takes through the Earth’s internal layers: - \(P\): propagation through mantle.
- \(K\): propagation through the outer core (since it is liquid).
- \(I\): propagation through the inner core. Step 2: Analyze the given ray path.
From the figure: - The P–wave originates at the earthquake focus.
- It travels through the mantle.
- It enters and passes through the outer core.
- It emerges back through the mantle and reaches the surface. This corresponds to the seismic phase notation \(\mathbf{PKP}\). Step 3: Elimination of incorrect options.
- PcP: A P–wave reflected at the core–mantle boundary (does not go through the core).
- PKP: A P–wave that travels through mantle, outer core, and back into mantle.
- PPP: A P–wave that reflects within the mantle multiple times, never enters the core.
- PmP: A P–wave reflected at the Moho discontinuity. Final Answer: \[ \boxed{\text{PKP}} \]