Earthquakes

Question 1

What is an earthquake

What is a volcano

Answer 1

The shaping of the earth”s crust causing destruction. Vibrations caused by earths movement at plate margins and major fault lines ( cracks in the earths surface)

Where the lava erupts at the earths surface

Question 2

Why do earthquakes happen

Answer 2

1 two plates at a plate margin cannot move past each other easily
2 the two plates become locked
3 friction causes pressure to build
4 suddenly pressure is released and plates jolt into a new position.
5 this causes seismic waves - vibrations caused are earthquakes

Question 3

What is the focus
What is the epicentre
What is the fault
What are seismic waves

Answer 3

1 where the earthquake happens
2 where humans first feel it above the earths surface
3 a crack in the ground
4 seismic waves start at focus

Question 4

Name 2 ways we measure earthquakes?

Answer 4

1 Richter scale

2 Mercalli scale

Question 5

How many earthquakes happen each year
How many cause serious damage

What machine measures earthquakes

Answer 5

500,000 in total
Less than 1000 cause serious damage
Seismometer

Question 6

Explain the Richter scale

Answer 6

Measures magnitude of a tremor - how powerful
Uses seismometer
Magnitude expressed in whole numbers and decimal fractions
No upper limit - largest ever 9.8 range - Tohoku 2015
Logarithmic scale so scale is 10 times scale 5 and 100 times larger than 4
If the focus is known we can work out strength of earthquake that creates the seismic waves

Question 7

Explain the mercalli scale

Answer 7

Classifies earthquake effect using Roman numerals I-XII
Accounts for effects on earths surface -people and buildings
Numbers decided by people observing impact making judgment not by machine