Tectonics, Structure Of The Earth and Tsunamis

Question 1

What is oceanic crust mainly made of?

Answer 1

Basalt

Question 2

Which plate is thin but heavy and dense?

Answer 2

Oceanic plates

Question 3

What is the thickest layer of the earth?

Answer 3

The mantle (2,900km)

Question 4

What causes earthquakes and volcanoes?

Answer 4

The movement along the edges of the plates

Question 5

What is a constructive plate boundary? Give an example

Answer 5

A constructive plate boundary occurs when plates move apart. This causes volcanoes to be formed as magma wells up to fill the gap, and eventually new crust is formed.

An example of a constructive plate boundary is the mid-Atlantic Ridge.

Question 6

Give three facts about the inner core

Answer 6

It is made up of Iron and nickel, is solid and is the hottest part of the earth.

Question 7

What is the outer layer of the earth?

Answer 7

The crust

Question 8

Give three facts about the crust

Answer 8

It is thin, forms the ground we live on and is divided into several large pieces called plates

Question 9

Give three facts about continental plates

Answer 9

They are thick, old, and generally contain light rocks that are less dense, e.g granite

Question 10

What causes plates to move?

Answer 10

Convection currents

Question 11

What is a destructive plate boundary? Give an example.

Answer 11

When an oceanic and continental plate move together. The oceanic plate is forced underneath the lighter continental plate, creating an oceanic trench
An example is when the Nazca plate is forced underneath the South American plate.

Question 12

Give three facts about oceanic plates

Answer 12

They are thin, young and generally contain heavy rocks that are more dense e,g basalt

Question 13

How can volcanoes be monitored?

Answer 13

Thermal imaging techniques and satellite cameras can be used to detect heat around a volcano.

Question 14

Describe three things about the outer core

Answer 14

It is 1,200km deep, liquid and has similar temperatures to the inner core

Question 15

What is the Ring of Fire?

Answer 15

The Ring of Fire is a large basin area in the Pacific Ocean where lots of volcanoes and earthquakes occur.

Question 16

What are the plates of the earth?

Answer 16

The plates are the sub-layers of the earths crust that cause earthquakes, volcanoes mountains and oceanic trenches.

Question 17

What are plate boundaries/plate margins?

Answer 17

The edges of plates

Question 18

How do volcanoes erupt?

Answer 18

Magma rises through cracks in the Earth’s crust, and when this pressure is released magma explodes to the surface causing a volcanic eruption.

Question 19

Where do most earthquakes and volcanoes occur?

Answer 19

Earthquakes and volcanoes are most likely to occur either on or near plate boundaries

Question 20

Name the two types of plate:

Answer 20

Oceanic plate

Continental plate

Question 21

What are collision zones?

Answer 21

Collision zones are when two continental plates collide, neither of which go beneath each other, so they are forced upwards to create fold mountains.

Question 22

What are convection currents?

Answer 22

Convection currents are the movement within the earths mantle caused by the heat of the core. The mantle is very hot.

Question 23

What is the centre of the earth called?

Answer 23

The inner and outer core

Question 24

What is a conservative plate boundary? Give an example

Answer 24

A conservative plate boundary occurs when plates slide past each other in opposite directions. Friction gradually builds up and the plates slip past in a sudden movement. The shockwaves created produce an earthquake.

This occurs at the San Andreas Fault in California.

Question 25

Give two positive and negative aspects of volcanic activity

Answer 25

Positive:

• ash given off from the eruption will eventually settle and make the soil more fertile
• volcanoes are a great tourist attraction, benefitting businesses

Negative:

• many people are killed and many injured
• buildings are destroyed and the risk of disease being spread is high

Question 26

What are tsunami’s?

Answer 26

Large waves caused by underwater earthquakes

Question 27

What does ‘tsunami’ mean?

Answer 27

Harbour wave

Question 28

How can tsunami’s be prevented?

Answer 28

They cannot be prevented but

• early warning systems can be installed in coastal areas
• evacuation routes can be planned
• warning signs of tsunami’s can be known

Question 29

What is a mountain belt?

Answer 29

A series of mountains being forced upwards into fold mountains

Question 30

What is an ocean trench?

Answer 30

A large ditch in the ocean bed marking a subduction zone near to a plate boundary