Volcanic Eruptions and Their Effects

Volcanic eruptions are classified based on magma composition. Fluid magma forms shield volcanoes, while gas-rich magma creates cone volcanoes. Viscous magma can cause explosive eruptions with ash columns. Silica-rich magma leads to highly explosive eruptions that can affect climate.

What is the primary factor used by volcanologists to categorize volcanic eruptions?

• The height of the volcano

• The temperature of the lava

• The location of the volcano

• The composition of the magma

What type of volcano is formed by basalt-rich magma?

• Composite volcano

• Shield volcano

• Cinder cone volcano

• Stratovolcano

What happens when magma contains gas?

• It causes the volcano to collapse

• It results in the ejection of ash and rocks

• It creates a lava lake

• It forms a shield volcano

What is the effect of more viscous magma on volcanic eruptions?

• It causes explosive eruptions

• It leads to gentle eruptions

• It results in continuous lava flow

• It forms underwater volcanoes

How does silica content affect the explosiveness of a volcanic eruption?

• Lower silica content increases explosiveness

• Higher silica content makes eruptions less explosive

• Silica content has no effect on explosiveness

• Higher silica content increases explosiveness

What happens when the pressure under a volcanic cap becomes too great?

• The volcano becomes dormant

• The cap is blown off, causing an explosion

• The volcano erupts gently

• The magma cools and solidifies

What is the speed of the scorching cloud that can result from a volcanic eruption?

• Several kilometers per hour

• Several meters per hour

• Several thousand kilometers per hour

• Several hundred kilometers per hour

What is a characteristic feature of the most explosive volcanic eruptions?

• Formation of a lava lake

• Creation of an umbrella-shaped ash plume

• Formation of a caldera

• Continuous lava flow

What can be a long-term effect of the most violent volcanic eruptions?

• Change in the planet's climate

• Increase in volcanic activity

• Formation of new islands

• Decrease in ocean levels