The Mohorovicic Discontinuity

Question 1

Following an Earthquake what type of body waves occur?

Answer 1

The first - Primary waves.

Second - Secondary waves.

Question 2

Differences between the 2 waves?

Answer 2

Primary - compression and expansion. Solids, liquids, air.

Secondary - side to side, up and down. Solids,

Question 3

In what year were 4 seismic waves detected?

Answer 3

1909.

Question 4

In 1909 what did they find out about the seismic waves?

Answer 4

The S and P waves closest to the epicentre were travelling slower.
Further from the epicentre shock waves travelling faster.

Question 5

Why do the waves travel at different speeds depending on the distance from the epicentre?

Answer 5

The waves are reflected and refracted when they meet rocks with different densities.
More dense rock = waves speed up.
Less dense rock = waves slow down.

Question 6

Why do waves travel slower nearest the epicentre?

Answer 6

The waves had travelled from the focus of the Earthquake through the upper layer of the crust.

Question 7

Why do waves travel faster away from the epicentre?

Answer 7

Waves passed through denser material in Earth’s core.

Denser material speeds up waves and deflected them.

Question 8

What is the density in the mantle and Earth’s crust?

Answer 8

2.9g/cm3 - 3.3q/cm3.