Types of Volcanoes- Class Notes

advertisement
Types of Volcanoes
Volcanoes at Divergent Boundaries:

Plates pull apart

Lithosphere becomes thinner

Cracks form/rift zones

Rock rises, decrease in pressure, rock melts and forms magma

When magma comes to the surface, it is called lava
*Mid Ocean Ridges

Volcanic mountain chains form when two tectonic plates are apart.

Magma moves upward from the mantle

They are under water

Some magma erupts as basaltic lava on the floor

As plates continue to move away from each-other, older oceanic
lithosphere moves away from the mid-ocean ridge

New crack from, and new lithosphere forms in the rift zone

This process is called sea floor spreading

These are non-explosive eruptions/volcanoes continue to get bigger
Volcanoes at Hot Spots:

Active

Located over a mantle plume

Mantle plumes are columns of hot, solid rock that rise through
*Shield

Usually forms at hot spots

Forms from layers of lava left from many non explosive eruptions

Layers of lava create volcanic mountains

The side of a shield volcano are not very steep

The volcanoes are very large

The base of a large shield volcano can be more than a 100 km in
diameter
Volcanoes at Convergent Boundaries:

Two plates push together with one subducting under the other.

The lithosphere contains water which is released in to the mantle and
the overlying crust.

This causes the temperature to drop and the rock melts

The magma that forms comes to the surface of the crust and erupts

volcanoes form at these plate boundaries forming a parallel chain
*Cinder Cone

It’s the smallest type of volcano

They have a wide summit

They reach no more than 300 meters high

Form from moderately explosive eruptions

Made from pyroclastic material

They erupt only once in their lifetime

They are the most common type of volcanoes

They have steep sides
*Composite

They are the most recognizeable

They may occur at intervals of 100’s of years or more

They are also known as strato-volcanoes

They form from pyroclastic material and quieter flows of lava

Generate many explosives

Sides get steeper towards the summit

Have a broad base
Download
Related flashcards
Cartography

28 Cards

Create flashcards