Subduction Zones and Island Formation

The video explains the process of oceanic plate subduction, where one plate is subducted under another, leading to partial melting and the formation of underwater sea mounts or volcanic islands. The angle of the subducting plate affects the distance of these formations from the subduction zone. It also discusses the formation of volcanic island arcs and the role of mantle plumes in creating island chains, such as the Hawaiian Islands. The Hawaiian Islands are formed as the Pacific plate moves over a stable mantle plume, resulting in a series of volcanic islands of varying ages.

What happens to the subducted oceanic plate as it nears the mantle?

• It rises to the surface.

• It remains unchanged.

• It partially melts.

• It completely dissolves.

What determines the distance of sea mounts or islands from the subduction zone?

• The temperature of the mantle.

• The angle of the subducting plate.

• The speed of the oceanic plate.

• The size of the oceanic plate.

What is a volcanic island arc?

• A series of islands formed parallel to a plate boundary.

• A single large island formed by volcanic activity.

• An underwater mountain range.

• A circular island formed by a single volcano.

What role do mantle plumes play in island formation?

• They prevent volcanic activity.

• They create a series of islands as plates move over them.

• They cool the oceanic crust.

• They cause earthquakes.

How do the ages of the Hawaiian Islands vary?

• The islands get older as you move east.

• They are all the same age.

• The islands get younger as you move southeast.

• The islands get older as you move southeast.

What does the age variation of the Hawaiian Islands suggest?

• The Pacific plate is stationary.

• The Pacific plate moved over a hotspot.

• The islands formed simultaneously.

• The islands are not volcanic.

Which island is part of the larger chain that includes the Hawaiian Islands?

• Madagascar

• Iceland

• Midway

• Greenland

What evidence supports the movement of the Pacific plate over a mantle plume?

• The presence of only one island.

• The uniform age of all islands.

• The progressive age difference of islands and sea mounts.

• The lack of volcanic activity.

Where does the chain of islands and sea mounts start near?

• The Mariana Trench

• The San Andreas Fault

• The Mid-Atlantic Ridge

• The Aleutian Trench

How old can the structures in the chain near the Aleutian trench be?

• 10 million years

• 50 million years

• 70 million years

• 100 million years