Magma Types and Their Properties

The video explains how silica content in magma affects its viscosity and explosiveness. Higher silica content leads to higher viscosity, making magma thicker and more explosive due to trapped gases. Basaltic magma has about 50% silica, andesitic around 60%, and rhyolitic about 70%. Basaltic magma is the least explosive, andesitic is moderately explosive, and rhyolitic is the most explosive. The flow characteristics of these magmas vary, with basaltic being thin and runny, andesitic having an intermediate flow, and rhyolitic being the most viscous and slowest flowing.

What is the relationship between silica content and magma viscosity?

• Higher silica content decreases viscosity.

• Higher silica content increases viscosity.

• Lower silica content increases viscosity.

• Silica content does not affect viscosity.

Which type of magma has the lowest silica content?

• Rhyolitic magma

• Andesitic magma

• Basaltic magma

• All have the same silica content

What is the approximate silica content in andesitic magma?

• 80%

• 70%

• 60%

• 50%

Which type of magma is the most explosive?

• None of the above

• Rhyolitic magma

• Andesitic magma

• Basaltic magma

How does basaltic magma typically flow on Earth's surface?

• Does not flow

• Moderate and sticky

• Thin and runny

• Thick and slow

What is the flow nature of andesitic magma compared to basaltic and rhyolitic magmas?

• Thinner than both

• Thicker than both

• Intermediate between the two

• Does not flow

Which magma type is the most viscous?

• Basaltic magma

• All have the same viscosity

• Andesitic magma

• Rhyolitic magma