1.15 Seismic Waves

Question 1

What are the number of things that can happen when a wave arrives at a boundary between materials? (4)

Answer 1

• It can be completed reflected.
• It can be partially reflected.
• The wave may continue travelling in the same direction but at a different speed.
• It can be refracted.

Question 2

What happens when theres an earthquake somewhere?

Answer 2

It produces seismic waves which travel out through the Earth.

Question 3

What do we use to detect the waves that earthquakes produce?

Answer 3

Seisometers

Question 4

What do seismologists do?

Answer 4

They work out the time it takes for the shock waves to reach each seismometer. They also note which parts of the Earth don’t receive the shock waves at all.

Question 5

What happens when seismic waves reach a boundary between different layers of material?

Answer 5

Some waves will be absorbed and some will be refracted.

Question 6

What happens when seismic waves are refracted?

Answer 6

They change speed gradually, resulting in a curved path. But when the properties change suddenly, the wave speed changes abruptly, and the path has a kink.

Question 7

Describe P-waves (3)

Answer 7

• P-waves are longitudinal.
• They travel through solids and liquids.
• They travel faster than S-waves.

Question 8

Describe S-waves (3)

Answer 8

• S-waves are transverse.
• They travel only through solids.
• They’re slower than P-waves.

Question 9

Which seismic waves travel faster?

Answer 9

P-waves