Earth And Natural Disaster

Question 1

Order of the 4 parts of the earth

Answer 1

1. Crust
2. Mantle
3. Outer core
4. Inner core

Question 2

Crust

Answer 2

• thinnest layer
• only 8-65km thick
• made of less dense rock so floats on mantle

Question 3

Mantle

Answer 3

• thickest part of earth
• 2900km thick + denser than crust
• upper mantle is rigid but lower mantle is semi-molten and has convection currents

Question 4

Outer core

Answer 4

• 2200km thick
• made out of molten iron and nickel

Question 5

Inner core

Answer 5

• made of solid iron and nickel
• densest layer of earth because is under immense amts of pressure
• 1260km thick

Question 6

What 2 layers is the lithosphere made of?

Answer 6

Crust + upper mantle

Question 7

Constructive margin

Answer 7

• plates diverge (move away from each other)
• can form volcanos bc of rising magma

Question 8

Destructive margin

Answer 8

• occur between a continental + oceanic crust plate
• converging (move towards each other)
• oceanic plate subducts under the continental as its denser
• plates can get stuck underneath each other and when they slip it’s releases lots of pressure creating earthquakes and fold mountains (volcanoes as there’s rising magma)

Question 9

Collision margin

Answer 9

• occurs when 2 continental plates converge
• both plates of equal density so they stay at same level
• fold mountains are created w no lava bc there’s no rising magma underneath

Question 10

Conservative margin

Answer 10

• plates move alongside each other
• plates can stick together and friction builds up. When the friction is released, it’s can release as a large earthquake
• no volcanoes as there’s no rising magma

Question 11

Plate margin

Answer 11

The line where 2 adjacent tectonic plates meet

Question 12

Focus

Answer 12

The point underground where plates slip and the seismic waves come from

Question 13

Epicentre

Answer 13

The point directly above the focus on the surface.

Question 14

Liquefaction

Answer 14

When soft sediment like mud can behave like a liquid when shaken by seismic waves

Question 15

What is a primary hazard?

Answer 15

a hazard that is caused immediately by event

Question 16

Secondary hazard of volcanic eruptions/earthquakes

Answer 16

A delayed hazard that was caused by the volcano/ earthquake and was more of the aftermath of the event. eg liquefaction, tsunamis, pyroclastic flow

Question 17

Stratovolcanoes - found on constructive or destructive margins?

Answer 17

Found in destructive margins such as those of the pacific ring of fire

Question 18

Stratovolcanoes - do they have acidic or basic lava?

Answer 18

Acidic lava

Question 19

Stratovolcanoes - explosive or effusive eruptions?

Answer 19

Eruptions are explosive and infrequent as the lava can get stuck in the vents and explode strongly from a pressure buildup

Question 20

Stratovolcanoes - what is another name for them?

Answer 20

Composite cone, as its formed out of many layers of solidified lava and compressed ash

Question 21

Stratovolcanoes - what type of base and slope do they have?

Answer 21

They have a narrow base and a steep slope as lava doesn’t travel very far from the base before solidifying

Question 22

Shield volcano - found on constructive or destructive margins?

Answer 22

Found on constructive margins

Question 23

Shield volcano - what type of base and slope does it have?

Answer 23

Very wide base and gentle slopes as lava travels very far from vent before solidifying

Question 24

Shield volcanoes - are eruptions effusive or explosive?

Answer 24

Explosions are effusive and frequent

Question 25

Shield volcano - does it have acidic or basic lava?

Answer 25

Basic lava

Question 26

Acidic lava - high or low viscosity?

Answer 26

High viscosity and sticky lava that doesn’t travel far from the vent before solidifying

Question 27

Acidic lava - high or low temperature?

Answer 27

Relatively low temperature of 800ºC

Question 28

Basic lava - high or low viscosity?

Answer 28

Low viscosity and runny lava and it travels very far from vent before solidifying

Question 29

Basic lava - high or low temperature?

Answer 29

High temperatures of 1200ºC

Question 30

Continental crust - more or less dense?

Answer 30

Less dense crust

Question 31

Continental crust - what on earth does it make up?

Answer 31

It makes up the earth’s landmasses

Question 32

Continental crust - how thick is it?

Answer 32

30-50km thick

Question 33

Continental crust - what is it mostly made of?

Answer 33

It’s mostly made of granite

Question 34

Oceanic crust - more or less dense?

Answer 34

More dense

Question 35

Oceanic crust - how thick is it?

Answer 35

Average 7km thick

Question 36

Oceanic crust - what on earth does it make up?

Answer 36

It forms the earth’s sea floor

Question 37

Oceanic crust - what’s it mostly made out of?

Answer 37

Basalt

Question 38

Give 3 reasons why people would live in areas of volcanic hazards

Answer 38

• volcanic ash breaks down to form fertile soil, making it easier and better to farm on
• people may be unaware that they live anywhere that’s hazardous (e.g a dormant volcano for 100s of years)
• people’s family have lived in a hazardous area for generations - a strong tie is developed that makes them reluctant to move elsewhere

Question 39

Primary hazard of earthquakes and volcanoes example

Answer 39

EQ = shaking + displacement caused by seismic waves
V = pyroclastic flow, volcanic bombs, lava flow

Question 40

Secondary hazards of earthquakes and volcanoes examples

Answer 40

EQ = landslides, liquefaction and avalanches + tsunamis
V = Lahar, Jokulhaup, tsunamis, climate change

Question 41

Explain distributivni of earthquakes and volcanoes

Answer 41

• EQ + V correspond to plate margins
• EQ = destructive margins mostly
• V = only constructive and destructive
• Hawaiian hotspot