Geography Volcanoes And Earthquakes

Question 1

Names the different layers of the Earth

Answer 1

Inner core
Outer Core
Mantle
Crust

Question 2

Characteristics of the Inner Core

Answer 2

Hottest part of the Earth
It is solid
1260m thick
Made up of metal, mainly iron mixed with nickel

Question 3

Outer core characteristics

Answer 3

This part of the core is liquid
About 2220km thick
Made up of iron mixed with nickel

Question 4

Mantel characteristics

Answer 4

Thickest part of the Earth at about 2900km thick
The outer mantle is hard, but further in it is like soft toffee

Question 5

Crust characteristics

Answer 5

8-65km thick
This is like the earths hard skin.
Made form less dense rock so able to float on the mantle

Question 6

Oceanic Crust characteristics

Answer 6

Forms on ocean floor
Denser (heavier)
Thinner - on average 7km thick
Mainly made of basalt

Question 7

Continental Crust characteristics

Answer 7

Makes up land masses
Less denser (lighter)
Thicker - on average 50km thick
Mainly made of granite

Question 8

Constructive margin

Answer 8

When the two plates are diverging above the upward plume of a convection cell. Magma rises through the gap between the two plates, resulting in volcanoes.There are lots of eruptions and earthquakes along constructive margins but they are generally gentle.

Question 9

Destructive margins

Answer 9

They occur when two plates one made of oceanic crust and one made of continental crust are converging. This can lead to pressure in a sudden slippage of the plates, resulting in a powerful earthquake and volcanic eruptions.

Question 10

Subduction

Answer 10

At destructive plate margins when the two plates meet, the oceanic plate dives beneath the continental plate, because it is denser. This process is known as subduction.

Question 11

How are fold mountains created?

Answer 11

The continental crust of a destructive plate margin buckles upwards, creating a range of fold mountains.

Question 12

Collision margins

Answer 12

A collision margin occurs when two plates made of continental crust converge. Because neither plate is denser than the other, subduction does not occur. Therefore, the plates simple buckle up to create a range of fold mountains. There are no volcanos along collision margins but there are powerful earthquakes.

Question 13

Conservative margins

Answer 13

Conservative plate margins occur when two plates move alongside to one another in opposite directions or in the same directions. When the plates slip, this pressure is released as a powerful earthquake. There are no volcanos.

Question 14

Epicentre

Answer 14

The point underground where the plates slip and from where the seismic waves radiate outwards.

Question 15

Focus

Answer 15

The point in the Earths surface directly above the focus; shaking here will be strongest.

Question 16

Aftershocks

Answer 16

Smaller earthquakes that occur in the hours, days, weeks and months following the main ever
Not caused by the plates slipping a little more as they settle down into their new configuration.

Question 17

Seismic waves

Answer 17

Energy waves that radiate out from the focus and cause the ground to shake, Primary waves stretch compress the ground, whilst secondary waves shake it from side to side.

Question 18

Fault line

Answer 18

A fracture in the rock at a plate margins when where pressure builds up if the moving plates stick.

Question 19

Magnitude

Answer 19

The higher the magnitude of an earthquake, the more energy is released and the greater the potential for damage to buildings and therefore deaths/injuries to people.

Question 20

Richter Scale

Answer 20

It assesses the amount of energy released by the earthquake, the intensity of shaking. It is a logarithmic scale, which means that every point you go up on the scales sees a 3 fold increase in energy released.

Question 21

Mercalli Scale

Answer 21

It assesses at the impacts of an earthquake by looking at things like the structural damage to buildings.This is correlated with the earths energy, but is influenced by other factors too.

Question 22

Acidic lava and basic lava differences

Answer 22

• acidic lava is viscous, is light in colour and has higher silica content. Basic lava is non-viscous, is darker in colour and has lower silica content.

Question 23

Stratovolcanoes

Answer 23

They are found on constructive margins.
Has basic lava and this means that eruptions are effusive and more frequent. The lava flows relatively rapidly from the vent. The volcano that is created has a very wide base but very gentle slopes.

Question 24

Stratovolcanoes

Answer 24

Found on destructive margins. They have acidic lava. It is steep.