Discover Geography WB8 Sample

Why do some volcanic eruptions cause more destruction than others?

1.1 What are volcanoes and how are they distributed?

1 Suggest a link between volcanic eruptions and food production.

2 What is the approximate temperature range of the magma that reaches the surface in volcanically active areas?

3 What is meant by a volcanic hot spot?

Chapter 1 Why do some volcanic eruptions cause more destruction than others?

4 What are the names of the two hot spots (mantle plumes) labelled A and B on the map in Figure 1.1?

Figure 1.1 Location of the world’s volcanic zones.

1 Suggest two of the different ways in which we can classify volcanoes.

2 With the aid of a labelled diagram, describe the typical shape of: a a cinder cone b a shield volcano.

3

Chapter 1 Why do some volcanic eruptions cause more destruction than others?

b If an eruption is classified as 6 on the VEI, how would this eruption be described?

Sample

4 Describe the typical characteristics of an effusive eruption.

5 Draw a field sketch of Chimborazo using Figure 1.7 in the Student’s Book.

6 Complete this fact file for Chimborazo: Type of volcano:

Describe its shape:

Explain how it was formed:

1 Name two different types of lava that can be produced by volcanic activity.

2 The image below shows an eruption at Fagradasfjall in southwest Iceland.

a What type of eruption can be seen in the image?

b What landscape features are likely to be formed by this eruption?

Figure 1.2 An eruption of Mount Fagradasfjall in Iceland.

Chapter 1 Why do some volcanic eruptions cause more destruction than others?

3 What is the typical size of volcanic ash according to the classification of tephra size?

4 What are lapilli? Explain how they are formed and where they are found.

Predict

5 Look at Figure 1.3, which shows the depths of ash that were deposited by a volcanic eruption. The vent is marked on the diagram. An isopach line is drawn on showing areas which received 30 cm of ash.

Draw lines (which will be roughly circular or egg shaped) for the following ash depths: 10 cm

20 cm

40 cm

50 cm

Chapter 1 Why do some volcanic eruptions cause more destruction than others?

Instructions

•Remember that the lines must join any points with the same value.

•Isopach lines cannot cross or touch.

•The line must pass between values which are higher or lower than its value.

•The lines will form oval shapes or circles.

Figure 1.3 An isopach map showing depths of ash with distance from a volcanic vent.