Magma Viscosity Factors: What Doesn't Affect It? Quiz

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Questions and Answers

What is the relationship between the temperature of magma and its viscosity?

As the temperature of magma decreases, the viscosity of magma increases.

As the temperature of magma increases, the viscosity of magma decreases. (correct)

As the temperature of magma increases, the viscosity of magma increases.

There is no relationship between the temperature of magma and its viscosity.

Which factor does NOT affect the shape of the volcanic cone?

Composition of the magma

Eruption history of the volcano (correct)

Amount of gas in the magma

Temperature of the magma

What type of volcanic cone is formed from alternate solidification of both lava and pyroclastic deposits?

Intrusive volcano

Shield volcano (correct)

Cinder cone

Composite volcano

Which factor affects the viscosity of magma the most?

The composition of the magma Signup and view all the answers

Which of the following is NOT a type of volcano based on its volcanic cone?

Intrusive volcano Signup and view all the answers

How does the amount of gas in the magma affect its viscosity?

The more gas in the magma, the higher the viscosity. Signup and view all the answers

What property of a material refers to its resistance to flow?

Viscosity Signup and view all the answers

Which factor can affect the viscosity of magma?

Amount of dissolved gases in the magma Signup and view all the answers

What determines the nature of a volcano's eruption?

Magma's temperature, chemical composition, and gas content Signup and view all the answers

What feature is common to cinder cones?

Steep slope and wide crater Signup and view all the answers

Which type of volcano is formed from alternate solidification of lava and pyroclastic deposits?

Stratovolcano Signup and view all the answers

How does the composition of magma affect its viscosity?

Higher silica content increases viscosity Signup and view all the answers

How does the temperature of magma affect its viscosity?

Viscosity decreases as temperature increases Signup and view all the answers

Which factor tends to increase the ability of magma to flow?

Presence of gases like water vapor Signup and view all the answers

What type of lava is likely to form a thin sheet due to its ability to travel far before solidifying?

Lava with low silica content Signup and view all the answers

Which type of lava is likely to form a dome or columnar structure?

Lava with high silica content and low gas content Signup and view all the answers

How does the composition of magma affect its viscosity?

Magmas with high silica content are more viscous Signup and view all the answers

What is likely to happen if lava has a low amount of gas and high silica content as it rises?

It will form a columnar plug in the vent Signup and view all the answers

Study Notes

Volcanoes and Magma

A volcano is a natural opening in the Earth's structure where molten rocks, hot gases, smoke, and ash are ejected.
Volcanoes are classified according to their record of eruption and shape (shield, cinder, and composite).

Factors Affecting Viscosity of Magma

Viscosity is the property of a material's resistance to flow, described as its thickness and stickiness.
Three primary factors affect the viscosity of magma: temperature, chemical composition, and amount of dissolved gases.

Temperature and Viscosity

Higher temperature of magma decreases its viscosity.
As lava flows, it cools, and its viscosity increases, making it harder to flow.

Composition and Viscosity

Magmas with high silica content are more viscous than those with low silica content.
Magmas with low silica content are relatively fluid and can travel far before solidifying.

Gas Content and Viscosity

Dissolved gases in magma (mainly water vapor) increase its ability to flow.
Loss of gases in near-surface environments makes magma more viscous, forming a dome or columnar shape.

Viscosity and Lava Flow

Lava with low viscosity (low silica content) can travel a great distance, forming a thin sheet.
Lava with high viscosity (high silica content) is too viscous to travel far and tends to break up as it flows.
Lava with low gas content and high silica content is very viscous and does not flow out at all, forming a columnar plug in the vent.
Lava with low gas content and high viscosity piles up in the vent, resulting in a dome.

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Description

Test your knowledge on how temperature and composition of magma affect its viscosity. Learn how temperature influences viscosity and why magmas with high silica content are more viscous than those with low silica content.