3.3 Earthquakes

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• Middelbare school
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• Leerjaar 1

3.3 Earthquakes

Earthquake

After studying this section

You are able to:

• Explain why an earthquake takes place.
• Describe the effects of an earthquake.

Shaking Earth

Earthquake = Shockwaves which are caused by convergent or transform plate movement.

The movement of plates is registered on a seismograph.
The size of an earthquake is measured on the Richter scale.

Magnitude = The size of an earthquake.

Richter Scale

Mercalli Scale

Hypocentre and epicentre

Epicentre: Central point of the earthquake on the Earth’s surface.

Hypocentre: Location in the Earth where the stress has been released.

Effects of an earthquake

• Aftershocks: Tremors following the main earthquake. 
  
• Buildings and infrastructure (roads, cables, etc.) collapse. 
  
• Victims (injuries or even deaths). 
  
• Landslides: Soil and rocks wiggle loose and slide down the hill. 
  
• Liquefaction: The soil becomes liquid and cars and buildings sink into it. 
  

A landslide caused by an earthquake damaged the road.

Soil liquefaction after an earthquake in New Zealand.

Tsunami

Tsunami = A giant wave caused by an earthquake underneath the ocean.

When the waves reach shallower water:

• Their height can increase by several metres.
  
• The shallow water slows the wave.
  
• The waves get closer together.
  

Tremors in Groningen, caused by production of natural gas. Relatively small tremors, but they do cause damage to houses!

In 2011 an earthquake was felt in Leerdam. There is a fault in Limburg which can cause earthquakes in our country.

What indicates the size of an earthquake?

1. Magnitude
2. Richter scale
3. Epicentre
4. Seismograph

What do we call the central point of an earthquake on the earth's surface?

1. Magnitude
2. Hypocentre
3. Epicentre
4. Seismograph

What do you see in the picture?

What happened in the photo?

What to remember

Go to the planner in Teams for the homework