Volcanoes

Highly explosive volcanoes tend to have what type of magma?

• magma with high silica, high viscosity, and higher gas content
• magma with low silica, low viscosity, and lower gas content
• magma with low silica, high viscosity, and lower gas content
• magma with no silica, high viscosity, and no gas content

A  line of volcanic activity that surrounds the Pacific Ocean basin is the 

• Ring of Fire
• Aleutian Islands
• Hawaiian Islands
• Caribbean Islands

How thick something is or the ability of a fluid or liquid to flow is its 

• viscosity
• density
• velocity 
• flowability 

What kind of volcano is made of alternating layers of lava and tephra/pyroclastics?

• shield

• composite

• cinder

5. What is the least explosive type of volcano?

• Shield

• Composite

• Cinder Cone

Which of the following factors helps determine whether a volcanic eruption will be violent or relatively quiet?

• amount of dissolved gases

• temperature of magma

• composition of magma

• all of the above

Which type of volcano has the widest base?

• Cinder
• Composite
• Shield

Why does magma form at convergent boundaries?

• Decompression melting: Pressure is released making the melting point of the mantle rock lower.

• Partial melting: Water lowers the melting point of the mantle rock

• Added heat: The temperature of the rock is increased.

• Pressure increase: Pressure on the mantle rock is increased.

Why does magma form at divergent boundaries?

• Water lowers the melting temperature of the mantle rock.

• Lowering the pressure lowers the melting point of the mantle rock.

• The temperature is increased.

• The pressure is increased

Hotspots are found ___.

• at divergent boundaries
• at convergent boundaries
• at transform boundaries
• within a plate (intraplate)