Volcanoes

Question 1

Why is volcanic activity so useful?

Answer 1

• Minerals from the ash cloud formed after an eruption can provide fertile land, which, after a while, is helpful for crops to grow.
• Volcanoes could bring up magma, which could help to generate electricity through geothermal generation methods.
• Production of new land often provides important and isolated habitats for species
• Tourism is a big driver of many economies - people are fascinated by volcanoes, especially ones that they can climb e.g Mt Fuji, Vesuvius, E16
• A potential benefit could be global cooling from a mega eruption (although has many downsides)
  Research into our beginnings as earth and a wider application of volcanic materials.
• Really important rocks and minerals such as obsidian, diamonds, sulphur can be brought to the surface

Question 2

What is a hotspot?

Answer 2

A hotspot is a superheated plume of magma which moves upward through weak points in the crust and creates volcano and island arcs (e.g. Hawaii)

Question 2

What is the difference between magma and lava?

Answer 2

Magma is when the molten rock is inside the volcano, whereas lava is when the molten rock has exited the volcano

Question 3

Why might wealthy people be at less risk (imagine both wealthy and not-so-wealthy people live the same distance from the volcano)

Answer 3

• They can leave faster (cars, helicopters in some situations)
• A specialist house would not assist them much
• Can pay for house insurance
• In areas with hospitals and other public services

Question 3

How does a volcano form at a constructive boundary?

Answer 3

As the two plates seep apart, magma is able to make its way in between the two plates. As the magma hits the ocean, the magma loses its temperature and solidifies on the ocean floor. Because the plates are always moving apart, the magma keeps seeping through the gap, and keeps building the volcano higher and higher. it either creates an ocean volcano, or builds up enough to be able to be a volcano on the land

Question 3

What is the viscosity of magma and lava determined by?

Answer 3

Temperature, dissolved gasses, and their chemical contents. The hotter the magma is and the lower the silica content, the less viscous it will be

Question 4

How does a volcano form at a destructive boundary?

Answer 4

First, the oceanic plate subducts. then it gets melted. then the magma from the oceanic plate rises due to it being less dense. Then, the magma rises and forms a volcano as it breaks through the crust.

Question 5

What is the difference between composite and shield volcanoes?

Answer 5

In a shield volcano, the lava is less viscous. This is because the lava is 1200°c, whereas the lava in a composite volcano is only 800°c. Composite volcanoes are more found in subduction zones and destructive plate boundaries, but shield volcanoes are more found on conservative plate boundaries. Shield volcanoes are flatter in shape because the lava is less viscous and can run farther. Shield volcanoes produce less ash because less of the volcano is destroyed, as shield volcanoes have a lower pressure, and therefore a lower explosivity level. Composite volcanoes have layers of lava and ash, but shield volcanoes have only layers of lava

Question 6

Give four primary volcanic hazards

Answer 6

• Lava flow
• Pyroclastic flows
• Ash fall
• Volcanic Gases

Question 7

Give three secondary volcanic hazards

Answer 7

Lahars
Landslides
Tsunami