Indirect evidence for the structure of the earth

Question 1

What is indirect evidence?

Answer 1

Evidence obtained using theoretical knowledge

Question 2

Name two forms of indirect evidence for the structure of the earth

Answer 2

Seismic waves

Density data

Question 3

How are P waves useful in providing information about the interior of the earth?

Answer 3

P waves have a compressive push movement and can pass through a liquid

Question 4

How are S waves useful in providing information about the interior of the earth?

Answer 4

S waves shear or shake and cannot pass through a liquid

Question 5

What do P and S waves do at the earth’s boundaries?

Answer 5

The waves reflect and refract at the boundaries and change velocity as the layers change composition and state producing a shadow zone.

Question 6

Between what degrees is the earthquake shadow zone?

Answer 6

103* and 142*

Question 7

What is the average density of the earth?

Answer 7

5.5 gm/cm^3

Question 8

What is the average density of the crustal rocks?

Answer 8

2.7- 2.9 gm/cm^3

Question 9

What can be inferred from the average density of the earth an the density of the crustal rocks?

Answer 9

There must be a high density material in the core of the earth