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1. Name the plate boundary in figure 1. (1 marks)
2 .Describe the movement that occurs at this plate boundary (2 marks)
3 .Name one other boundary which can create a volcanic eruption. (1 marks)
1. Name the plate boundary in figure 1. (1 marks)
2 .Describe the movement that occurs at this plate boundary (2 marks)
3 .Name one other boundary which can create a volcanic eruption. (1 marks)
Figure 1Figure 1
Volcanoes Volcanoes
Learning objectives
• To describe how volcanoes are formed
• To develop a greater understanding of the structure of a volcano.
• To be able to identify and explain the different types of volcano.
A volcano is an opening or vent in the earth’s surface through which molten material erupts and solidifies as lava.
VentVentActive volcano – liable to erupt e.g. Mt Etna
Dormant (sleeping) volcano – a volcano which has not erupted for many years. For example, Mt Pinatubo erupted in 1991 after 500 years of dormancy.
Extinct volcano – a volcano which has not erupted for many thousands or millions of years e.g. Edinburgh.
Why might a volcano become extinct?
Why might a volcano become extinct?
In the back of your books you need to draw a diagram of how you think a volcano looks on the
inside (internal structure).
Key words to label your diagram with:Main vent
CraterSecondary vent
Magma chamberLava flow
In the front of your books draw a copy of the diagram with the correct labels.
These volcanoes are created at constructive margins. This is where two plates are moving apart from each other and magma moves to the surface through the gap.
These volcanoes are created at constructive margins. This is where two plates are moving apart from each other and magma moves to the surface through the gap.
The eruptions from these volcanoes are generally more gentle and can last for several months.
The eruptions from these volcanoes are generally more gentle and can last for several months.
A good example is the North America and Eurasian Plate creating Surtsey, Iceland.
A good example is the North America and Eurasian Plate creating Surtsey, Iceland.
The emerging lava is more fluid and therefore the shape of the volcano is low and wide. This is why it is called a ‘shield’ volcano.
The emerging lava is more fluid and therefore the shape of the volcano is low and wide. This is why it is called a ‘shield’ volcano.
These are formed at destructive margins where one plate slides underneath the other.
These are formed at destructive margins where one plate slides underneath the other.
A slab of ocean floor slides down and is melted due to friction. This is called the subduction zone. This melted magma warms up slowly and mixes with water and carbon dioxide released from the rock.
A slab of ocean floor slides down and is melted due to friction. This is called the subduction zone. This melted magma warms up slowly and mixes with water and carbon dioxide released from the rock.
The hot magma is more sticky rises in violent eruptions to form steep sided volcanoes.
The hot magma is more sticky rises in violent eruptions to form steep sided volcanoes.
The eruption is explosive and rock molten and solid flies from the volcano. This is followed by gas and steam which forms huge clouds called nees ardentes.
The eruption is explosive and rock molten and solid flies from the volcano. This is followed by gas and steam which forms huge clouds called nees ardentes.
Layers of ash and lava build around the main vent to form a strato volcano.
Layers of ash and lava build around the main vent to form a strato volcano.
An example is Montserrat formed by the Caribbean and South American plate.
An example is Montserrat formed by the Caribbean and South American plate.
An example is Mauna Loa Hawii.
An example is Mauna Loa Hawii.
In places where the plate is particularly thin, magma may be able to escape to the surface.
In places where the plate is particularly thin, magma may be able to escape to the surface.
As the plate continues to move the volcano dies out and a new volcano is formed on another area of the plate.
As the plate continues to move the volcano dies out and a new volcano is formed on another area of the plate.
Hot spots can create chains of shield volcanoes. They therefore have gentle oozing lava.
Hot spots can create chains of shield volcanoes. They therefore have gentle oozing lava.
You are to think about one fact you have learnt this lesson. You are to turn this into a question
and stand behind your chair once ready.
E.g. Shield volcano eruptions are gentle.BECOMES
Describe the eruption at a shield volcanoes?
Learning objectives
• To be able to explain how and why the Mt St Helens eruption occurred.
• To assess the social, economic and environmental impacts caused by the eruption.
• Located in the state of Washington in the USA.
• Located on a destructive plate boundary, where a continental plate (North American) meets an oceanic plate (Juan de Fuca).
• It is a strato (cone) volcano.
• The volcano erupted in 1980.
• Deadliest and most destructive volcanic eruption in the history of the continental United States of America.
Watch the video closely and listen and look for information to fill in on your case study sheet
http://www.youtube.com/watch?v=-H_HZVY1tT4&feature=related
Primary effects Secondary effects
- 63 people were killed, mainly by poisonous gases.
Sediment carried downstream ruined barge transport on the Columbia River.
- Hot ash and gas destroyed forests and logging camps.
- Lahars (mudflows of ash and water) covered an extensive area surrounding the volcano.
Flooding destroyed communications such as road and railway bridges.
Ash blocked rivers destroying popular fishing sites and causing flooding. This in turn destroyed crops and livestock.
• You will be in three groups of six
• In your groups, you will be assigned the task of considering either the social, economic or environmental impacts of the Mt St Helens eruption.
• You must familiarise yourself with the impacts, becoming experts in your field.
• Three of you will be reporters, tasked with questioning each group on the facts they have found out.
• Team A – You are local residents who live and work in the Mt St Helens area
• Team B – You are government officials – who are concerned with the economic effects of the eruption
• Team C – You are employees of the environmental agency
Social
Economic
Environmental
