Infrasound and Seismic Waves

Question 1

what is infrasound?

Answer 1

sound with frequencies lower than 20 Hz

Question 2

where is infrasound used?

Answer 2

• in animals communicating (elephants and whales)

- volcanoes, avalanches and earthquakes

Question 3

what are seismic waves?

Answer 3

caused by earthquakes and explosions at a range of frequencies which travel out through the earth

Question 4

how are seismic waves detected?

Answer 4

seismometers

Question 5

how is infrasound helpful for scientists?

Answer 5

• can track animals for conservation purposes

- can try to predict events of explosions

Question 6

what do seismologists do?

Answer 6

• work out the time it takes for the waves to reach each seismometer
• note which parts of the earth don’t receive waves

Question 7

what happens when seismic waves reach a boundary between different layers of material in the earth?

Answer 7

some waves will be absorbed and some will be refracted

Question 8

what happens when the waves are refracted?

Answer 8

change speed gradually, resulting in a curved path

Question 9

what are the 2 types of seismic waves?

Answer 9

s-waves

p-waves

Question 10

by observing how seismic waves are absorbed and refracted, scientists can work out…

Answer 10

where the properties of the earth dramatically change

Question 11

what is based on these observations?

Answer 11

• our understanding of the internal structure of the earth

- the size of the earths core

Question 12

what are properties of p-waves?

Answer 12

• longitudinal
• travel through solids and liquids
• travel faster than s-waves

Question 13

what are properties of s-waves?

Answer 13

• transverse
• only travel through solids
• travel slower than p-waves