Restless Earth

Question 0

How thin is the crust?

Answer 0

20km

Question 1

Name the 4 parts of the earths structure starting from the outside

Answer 1

Crust, mantle, outer core and inner core.

Question 2

What is the crust divided into?( name both types)

Answer 2

Tectonic plates made of oceanic crust(thinner but more dense ) or continental crust which is thicker but less dense.

Question 3

Why do the plates move?

Answer 3

Due to the mantle( made of semi molten rock) that moves very slowly under them.

Question 4

What is a destructive plate margin? What happens to the plates?

Answer 4

Where two plates move against each other. The oceanic plate is forced down as its denser, if it is two continental plates they crash against each other but no crust is destroyed.

Question 5

In what direction do plates move in a constructive margin?

Answer 5

Away from each other, magma from the mantle rises to fill in the gap, creating new crust.

Question 6

In what plate margins are ocean trenches and volcanoes produced?

Answer 6

Destructive

Question 7

What is the margin called where two plates move sideways, past each other or in the same direction?

Answer 7

Conservative.

Question 8

In what plate boundary are fold mountains formed?

Answer 8

Destructive.

Question 9

Why are fold mountains good for tourism?

Answer 9

They have spectacular scenery, winter sports, trekking. Tunnels have been made to make quick roads.

Question 10

How are fold mountains used for farming?

Answer 10

Slopes are used to let animals graze, low slopes are used to grow crops which are sometimes used to feed the animals during the winter. Steep slopes are sometimes terraced.

Question 11

Other than tourism and farming? What else are fold mountains used for? Why?

Answer 11

HEP- steep sided mountains and high lakes make fold mountains ideal for generating hydro electric power.
Forestry
Mining- major source of metal ores

Question 12

How are fold mountains formed?

Answer 12

Sediments accumulate at a geosyncline(depression/dip in the soil), this turns into sedimentary rocks due to the pressure from the moving plates. Once there is enough pressure, this rocks no longer fit in and therefore fold, they can fold upwards(anticline) or downwards(syncline).

Question 13

Case study of fold mountains?

Answer 13

The Alps in central Europe.

Question 14

In what plate margins do volcanoes form? State how for each

Answer 14

Destructive- the oceanic plate moves down into the mantle due to it being more dense, where it melts. The magma then rises though cracks in the crust called vents until it reaches the surface, forming a volcano.
Constructive- magma rises up onto the gap created forming a volcano.

Question 15

What are the characteristics of a composite volcano?

Answer 15

Made up of ash and lava thats erupted and then hardened into layers.
Thick lava which flows slowly forming steep sides. Erupts rarely but when it does they are very explosive eruptions of acid lava.eg Mount Fuji in Japan

Question 16

Characteristics of a shield volcano?

Answer 16

Made up of only lava. Has runny lava which spreads over a large are forming a low and flat volcano. Frequent non violent eruptions of basic lava.Eg Mauna Loa in Hawaii

Question 17

What are dome volcanoes?

Answer 17

Same as composite volcanoes but made of only lava. Eg mount Pelée in the Caribbean

Question 18

What are the signs used to predict eruptions?

Answer 18

Tiny earthquakes, escaping gas and changes in the form of the volcano such as bulges in which magma has built under.

Question 19

What is the difference between basic and acid lava?

Answer 19

Acid lava has a high silica content and is more viscous and less runny. Basic lava is viceversa.

Question 20

What are pyroclastic flows?

Answer 20

Fast moving clouds of super heated ash and gas.

Question 21

What is a lahar?

Answer 21

A destructive mudflow on the slopes of a volcano. Formed when a ash cloud is intercepted by rain.

Question 22

What is a supervolcano?

Answer 22

A volcano that erupts with a much more massive volume than a normal volcano( at least 1000km*3 of magma).

Question 23

What may the dust from a supervolcano in the atmosphere produce?

Answer 23

Due to its large amounts it could block the sunlight and produce a volcanic winter (global cooling)

Question 24

When and where was the last volcanic eruption?

Answer 24

Indonesia 75k years ago.

Question 25

Give an example of a super volcano

Answer 25

Yellowstone

Question 26

What are the characteristics of a super volcano?

Answer 26

Flat
Cover a large area
Have a caldera( crater at thr top)

Question 27

How does a supervolcano form?

Answer 27

Magma rises through cracks in the crust to form a bif magma basin. The pressure makes the basin increase in size until it cracks, making massive lave eruptions. The bulge is no longer supported so it collapses spewing up more lava. After the eruption there is a massive crater(caldera).

Question 28

How are earthquakes formed?

Answer 28

Pressure builds up at a plate margin until these eventually jerk off, sending out shock waves (vibrations).

Question 29

What is the focus of an earthquake?

Answer 29

The point where an earthquake starts.

Question 30

What s an epicentre?

Answer 30

The point on Earths surface straight above the focus of an earthquake.

Question 31

How does the Richter scale measure an earthquake?

Answer 31

Depending on the energy released(magnitude) using a seisometer. Doesn t have an upper limit and every grade up is 10 times stronger than the one before.

Question 32

How does the Mercalli scale work?

Answer 32

Measures the effects of an earthquake through eyewitness. Goes from 1-12

Question 33

What s magma called once it erupts onto the surface?

Answer 33

Lava

Question 34

What are ocean trenches?

Answer 34

a long, narrow, deep depression in the ocean bed, typically one running parallel to a plate boundary and marking a subduction zone.