Answer:
When a seismic wave 'bounces backward' and reaches a boundary, it is called Reflection.
Step-by-step explanation:
- The seismic waves are the result of the landslides, earthquakes, volcanic eruptions, explosions by humans.
- They are the energy waves which travel through the earth's layers. To study the interior of the Earth, reflection of seismic waves is studied.
- When a wave reaches a 'boundary', there can be infinite paths it can take while bouncing back.
- This process is called reflection. Each path is noted with a 'set of letters' describing the phase and the trajectory.
- The 'upper case' represents the transmitted waves and the 'lower case' represents the reflected wave.