Volcanic Activity

Question 1

What is lava?

Answer 1

As the plates of the earth’s crust separate or collide, magma can make its way to the surface. When it reaches the surface, it cools and hardens. It is then called lava.

Question 2

How are mid-ocean ridges formed?

Answer 2

When plates separate under the ocean, lava can pour out along cracks on the earth’s surface forming a ridge. This lava can build up and become what is called a mid-ocean ridge.

Question 3

How are volcanic mountains formed?

Answer 3

Lava can force its way violently through a small hole known as a vent. When this happens, a volcanic mountain is formed.

Question 4

Explain the formation of volcanic mountains in 3 steps.

Answer 4

1. When two plates collide or separate, magma can rise from the mantle to fill the space that opens in the crust- the vent. We call this an eruption, and it can be violent due to the great pressure that the magma is under in the mantle.
2. When magma wells up from the magma chamber and reaches the surface, it cools and hardens. This is known as lava.
3. After many eruptions, layers of lava and ash build up around the vent, and a cone-shaped mountain is formed with a crater at the top from which lava flows.

Question 5

What are the 3 life cycles of a volcano?

Answer 5

Active:
Any volcano that has erupted in the past 10,000 years e.g Mount St Helens in North America.
Dormant:
A volcano that has not erupted in the past 10,000 years but is expected to erupt again in the future e.g. Kilimanjaro in Tanzania.
Extinct:
A volcano that is never expected to erupt again e.g. Mount Kenya in Kenya

Question 6

Where can an example of a mid-ocean ridge be found?

Answer 6

A mid-ocean ridge can be found in the middle of the Atlantic ocean, where a narrow chain of mountains called the mid-Atlantic ridge is located.

Question 7

Give an example of a volcanic island.

Answer 7

Iceland is an example of a volcanic island.

Question 8

N.E.E.D. Volcano

Answer 8

Name: Volcano
Example: Eyjafallajökull Volcano in Iceland
Explanation: Formation of a volcano card
Diagram: Copy or book drawing. Mention magma chamber, ash cloud, cone, central vent, side vent, crater, earth’s crust, lava

Question 9

What is the pacific ring of fire?

Answer 9

The pacific ring of fire is a horse-shoe shaped area containing many plate boundaries. It is home to almost 75% of the earth’s active volcanoes and is where almost 90% of the world’s earthquakes occur.

Question 10

What are the positive impacts of a volcanic eruption? (social, economic)

Answer 10

Social impact: Reduced unemployment - the development of tourism as a result of a volcanic eruption created jobs.
Increased tourism and employment

Economic impact:
Generated income - New tourist attractions are built
Fertile soil - Lava and ash are rich in nutrients, making the soils in volcanic areas very fertile and good for agricultural use.

Question 11

What is geothermal energy?

Answer 11

It is heat sourced from the ground and can be used to heat households.

Question 12

What are the negative impacts of a volcanic eruption? (social, economic)

Answer 12

Social impact:
Contaminated water supplies - Ash from an eruption can pollute local water. Animals can not drink this water.
Evacuation of locals - Locals may have to be evacuated due to the amount of ash in the air. They may have to wear face masks to avoid choking on the ash.

Economic impact:
Travel chaos - Flights may be cancelled due to poor visibility due to ash in the air and the fear that tiny ash particles would clog up the engines of aeroplanes.
loss of earnings - fresh produce is transported by plane so they can arrive quickly. Flight bans mean that products can’t be sold.