tectonic hazards

What is the Earth’s crust divided into?

Tectonic plates.

What are the two types of crust?

• Oceanic

• Continental

What are the characteristics of oceanic crust?

• Thin

• Heavy + dense

• Young

What are the characteristics of continental crust?

• Thick

• Light

• Old

Why do plates move?

Because of the convection currents in the mantle of the Earth.

Where do most earthquakes and volcanic eruptions occur?

By plate boundaries.

Why do most earthquakes and volcanic eruptions occur by plate boundaries?

Due to the tectonic activity occurring at plate boundaries - the movement of plates causes earthquakes and the rise of magma at destructive + constructive plate boundaries forms volcanoes

What are the 3 main types of plate margin?

• Destructive

• Constructive

• Conservative

How do the plates of a destructive plate boundary move relative to each other?

They move towards each other.

What are the two types of destructive plate boundary?

• Subduction (oceanic + continental)

• Collision (continental + continental)

What hazards occur at a destructive plate boundary?

• Earthquakes

• Volcanic eruptions

What landforms are formed at a destructive plate boundary?

• Volcanoes (S)

• Deep sea trenches (S)

• Fold mountains (C)

How is a deep sea trench and volcano formed at a (subduction) destructive plate boundary?

1. The oceanic plate subducts beneath the continental plate into the mantle, forming a deep sea trench.

2. This causes the subducted part of the oceanic plate to melt and create more magma

3. The magma rises into the cracks + breaks through to the surface of the continental plate.

4. Eventually when the pressure is high enough, it erupts, forming a volcano.

EX: Atacama Trench (Nazca + South American)

How are fold mountains formed at a (collision) destructive plate boundary?

The collision between the two continental plates causes the crust to fold upwards, forming fold mountains.

EX: Himalayas

How do the plates of a constructive plate boundary move relative to each other?

They move away from each other.

What hazards occur at a constructive plate boundary?

• Earthquakes

• Volcanic eruptions

What landforms are formed at a constructive plate boundary?

• Mid ocean ridges

• Volcanoes

How is a mid ocean ridge formed at a constructive plate boundary?

As the two oceanic plates move away from each other, magma rises to fill the gap. This solidifies and forms new oceanic crust, forming a mid ocean ridge.

EX: Mid-atlantic ridge (Eurasian + North American)

How is a volcano formed at a constructive plate boundary?

As the two plates move away from each other, magma rises to the surface of the crust which erupts to form a volcano.

How do the plates of a conservative plate boundary move relative to each other?

They move past each other, either in the same direction and at different speeds or in opposite directions.

EX: San Andreas Fault (Pacific + North American)

What hazards occur at a conservative plate boundary?

Only earthquakes.

What landforms occur at a conservative plate boundary?

None.