Restless Earth Key Terms

Question 1

Tectonic Plates

Answer 1

The rocks of the crust are fractured into huge segments known as tectonic plates. They move about very slowly, pushed and shoved around from underneath by currents within the mantle called convection currents.

Question 2

Continental Plates

Answer 2

Continental Crust is thicker, older and lighter, and is composed mainly of granite.

Question 3

Oceanic Plates

Answer 3

Oceanic crust is younger and heavier, it’s mainly composed of basalt. It is mainly formed at constructive margins or spreading mid ocean ridges.

Question 4

Constructive plate margins

Answer 4

At these plate margins the two Plates are moving apart from each other in opposite directions. Convection currents moving in opposite directions in the mantle move the two Plates apart. Magma rises to fill the gap.

Question 5

Destructive plate margins.

Answer 5

At destructive plate margins two plates move together, subduction can occur where heavier oceanic crust moves towards lighter continental crust. A range of landforms occur including deep ocean trenches, composite cone volcanoes and fold mountains. Earthquakes also occur at these margins.

Question 6

Conservative plate margins

Answer 6

This is when two plates slide past each other. This can result in a build up in pressure which causes earthquakes.

Question 7

Ocean trenches

Answer 7

This is a long deep depression in the ocean bed, often running parallel to a plate margin, it marks a subduction zone.

Question 8

Fold mountains

Answer 8

These are large mountains ranges where layers of rock have been crumpled when they have been pushed together. These are formed at destructive plate margins.

Question 9

Hydro Electric Power (HEP)

Answer 9

The term which refers to electricity being generated by water.

Question 10

Steep relief

Answer 10

Steep slopes and high lands

Question 11

Volcanoes

Answer 11

Mountains that explode which have violent consequences. They are geological landforms created by the intrusion of lava in the earths crust and by the eruption of Magmas onto the earths surface through vents.

Question 12

Shield Volcanoes

Answer 12

These volcanoes erupt loads of basaltic lava that gradually build up a wide mountain that forms a shield shape. The lava flows are very hot and very fluid, this makes them have long flows.

Question 13

Composite Volcanoes

Answer 13

Are formed from alternating layers of ash and lava. The lava is thicker and more viscous so it doesn’t flow as far. This results in steep sides and narrower base.

Question 14

Poor Soils

Answer 14

Low in nutrients, infertile

Question 15

Primary Effect

Answer 15

Are the immediate effect of an eruption. Examples consist of Deaths, injuries, damage to housing, loss of vegetation, loss of farmland and damage to industry.

Question 16

Secondary effects

Answer 16

These are knock on effects. Examples of these are mudflows, landslides and shortages of food.

Question 17

Immediate Response

Answer 17

Emergency help often includes emergency services or aid agencies. The focus of these will be providing water, food and shelter.

Question 18

Long term response

Answer 18

This usually involves reconstruction or putting in place preventative measures to reduce the impacts of future events.

Question 19

Supervolcanoes

Answer 19

A super volcano is a volcano on a massive scale. It is different from a normal volcano because it erupts at least 1000km^3 of material, (a normal volcano is 1000km^3). It forms a depression called a caldera (a normal volcano forms a cone shape) a super volcano has a ridge of higher land around it and it erupts infrequently.

Question 20

Prediction, Prevention, Preparation

Answer 20

A way of managing eruptions by monitoring volcanoes, planning evacuations and storing food and medical supplies.

Question 21

Earthquake

Answer 21

Vibrations in the earths crust that cause shaking on the surface. They are very unpredictable and they often occur without warning. We have no fully and accurate way of predicting when an earthquake will occur.

Question 22

Shock waves

Answer 22

When movements occur within the earths crust energy is released as seismic, or shock waves which travel through the crust.

Question 23

Focus

Answer 23

The point within the crust where the slippage occurs.

Question 24

Epicentre

Answer 24

The point on the surface above the focus.

Question 25

Richter Scale

Answer 25

This measures the energy of the earthquake. The scale is logarithmic.

Question 26

Mercalli Scale

Answer 26

This measures the effect of the earthquake and it runs from 1 to 12. The higher up the scale the more damage has occurred.

Question 27

Tsunami

Answer 27

A tsunami is a series of waves in the water caused by the displacement of a large volume of water, generally in an ocean. They can be caused as a result of an underwater earthquake where one plate jolts vertically upwards.