Waves And The Earth

Question 1

What’s the difference between p and S waves

Answer 1

Primary waves are faster and arrive first
Secondary waves are slower so arrive after
P waves are longitudinal and S waves are transverse
P waves travel through solids and liquids
S waves travel only through solids

Question 2

Longitudinal waves

Answer 2

Push pull wave
This is the same as p wave
Particles vibrate in the same plane that the wave travels in
Go through solid and liquid
III I I  I I III I  I  I  I  I III

Question 3

Transverse waves

Answer 3

Look like an S and move side to side
These are secondary waves
The particles vibrate perpendicular to the direction the wave is traveling
Can only go through solid

____ ____ _____
\ / \ /
\___/ \___/

Question 4

What waves can go through the earth

Answer 4

Transverse waves can travel through the earth but not through the outer core as its a liquid. They go in solid curves
Longitudinal waves can go through all layers of the earth but they refract through each layer

Question 5

How do earthquakes happen

Answer 5

Convection currents in the mantle (heating and cooling of magma making it go up and down) move the tectonic plates. The plates can move past each other because of friction which creates pressure. Once the force become too much the plates slip past each other fast which releases the seismic waves

Question 6

Why are earthquakes unpredictable

Answer 6

We can’t measure the pressure between plates
We can only detect them after they’ve happened
We don’t know when the plates will slip

Question 7

Earthquake model

Answer 7

A tub with water in and Some corks floating on the water
Heat under the tub that heats up the water and creates convection currants.
Corks are the plates
Water is mantle
Heat is core

Question 8

Earthquake graph.

Answer 8

Drawn using a seismometer
Starts of straight line
Then small tremors, these are the p waves
Then large waves, these are the transverse waves

Question 9

How can you measure the distance a wave has travelled using a seismometer

Answer 9

Record the time p waves are detected then record the time S waves are detected
Using a formula and difference in time you can work out the distance

Question 10

How can we find out where an earthquake started

Answer 10

We can use 3 seismometers
When an earthquake happens it is detected by each of the seismometers
We can tell how far away the wave has travelled but we don’t know where it happened
It may have been 1km from A. 2km from B and 3km from C
If we draw a radius around each seismometer based on how far the wave has travelled to get to them
We can see where the circles intercept
The point where all 3 circles meet is where the wave came from which is the epicentre