Restless Earth

Question 1

What is the Asthenosphere?

Answer 1

The sticky, dense layer of rock in the mantle

Question 2

What is the Lithosphere?

Answer 2

The crust and the solid top layer of the mantle

Question 3

What is the core made of?

Answer 3

Iron and Nickel

Question 4

Describe the differences between Oceanic crust and Continental crust.

Answer 4

Oceanic - made of Basalt, underneath water

Continental - made of Granite, underneath land

Question 5

Describe the differences between Granitic rock and Basaltic rock.

Answer 5

Granite - large crystals, formed by magma cooling slowly, orange-brown colour, makes continental crust
Basalt - no visible crystals, occurs in lava flows and sheets, black-grey colour, makes oceanic crust

Question 6

Explain how tectonic plates move.

Answer 6

Earth core gives off heat causing convection currents or movement of magma in the Asthenosphere causing the crust sitting on top of it to move and the tectonic plates move too.

Question 7

Outline the key features of the Earths structure.

Answer 7

Core - inner core (solid), outer core (liquid)
Mantle - above core, low density, upper solid, lower liquid
Crust - solid, low density, tectonic plates - oceanic (more dense, basaltic rock, below water) continental (less dense,thick, granitic rock, below land)

Question 8

Name all 12 tectonic plates.

Answer 8

Pacific, Antarctic, Philippines, Indo-Australian, North-American, Nazca, South-American, Caribbean, African, Eurasian, Iranian, Arabian

Question 9

Name the 4 types of plate boundaries.

Answer 9

Constructive - Plates pull away from each other
Destructive - Plate pushes under other
Collision - Plates push into each other
Conservative - Plates slide past each other

Question 10

Explain what happens at a Constructive plate boundary.

Answer 10

Convection currents cause oceanic plates move away from each other
Basaltic material and hot magma rises through gap
Mid ocean mountain range formed
Magma continues to rise to form a volcanic island

Question 11

Explain what happens at a Destructive plate boundary.

Answer 11

Convection currents move plates
Oceanic plate subducts under less dense continental plate
Forms a fold mountain and ocean trench
Magma rises through weaknesses forming volcanoes

Question 12

Explain what happens at a Collision plate boundary.

Answer 12

Convection currents cause two continental plates to move towards each other
Same density so no subduction
Crust buckles to form fold mountains

Question 13

Explain what happens at a Conservative plate boundary.

Answer 13

Convection currents cause plates to slide past each other
No subduction or magma therefore crust neither created or destroyed Stress builds up in crustal rocks from friction which causes earthquakes when released

Question 14

Define an earthquake.

Answer 14

The shaking of the Earth’s crust caused by rock movement.

Question 15

Define a volcano.

Answer 15

A cone shaped hill or mountain formed by the lava and ash from eruptions.

Question 16

Describe the 3 types of volcanoes.

Answer 16

Extinct - not erupted for 1000 years, shape worn away by wind and rain
Dormant (sleeping) - not erupted for years or even centuries but still seeps gas sometimes
Active - erupted recently and likely to erupt again

Question 17

What is the hot spot theory?

Answer 17

When hot magma rises to the surface pushing through a continental plate crossing over it, forming chains of volcanoes over thousands of years.

Question 18

Describe the features of a shield volcano.

Answer 18

Mainly formed by basaltic magma, Low, wide cone, large, gentle slope (lava drizzles/slides down)

Question 19

Describe the features of a composite volcano.

Answer 19

Made of andesitic lavas, steep sided, bumpy cone, layers of lava and ash.

Question 20

What are pyroclastics?

Answer 20

Pieces of ash and rock debris or material destroyed in explosive eruptions.

Question 21

Describe the features of basaltic magma.

Answer 21

High temp, low silica/gas, fluid lava flow, little explosive activity, found in shield volcanoes on conservative plate margins

Question 22

Describe the features of andesitic magma

Answer 22

Low temp, more silica than basaltic, dissolves gases, less fluid, more likely to explode when reaches surface, found in composite volcanoes at destructive plate margins.

Question 23

Describe the features of granitic magma

Answer 23

Low temp, High silica, viscous, sticky, gets stuck before reaches surface so not found in volcanoes.

Question 24

How is Ash formed?

Answer 24

From material destroyed in explosive volcanic eruptions.

Question 25

Define vulnerability.

Answer 25

How prone or likely a region is to damage and destruction from a tectonic hazard like an earthquake

Question 26

What is capacity?

Answer 26

The ability of a community to recover from the affects of a tectonic hazard.

Question 27

What is the difference between primary and secondary impacts of a tectonic hazard?

Answer 27

Primary: take place at the time of the event, directly caused by it.
Secondary: follow the event, indirectly caused by it

Question 28

Give two primary and secondary impacts of a tectonic hazard like an earthquake.

Answer 28

Primary: Building destroyed, people dying/injured
Secondary: spread of illnesses, social impacts like children can’t go to school, transport issues etc.

Question 29

Summarise the Kashmir earthquake.

Answer 29

Remote, poor region
Saturday 8th October 2005
During Ramadan
7.6 on Richter Scale
Epicentre at Muzaffarabad (capital of administration)
75,000 died
2.8 million homeless
Property cost $440 million

Question 30

Summarise the Loma Prieta earthquake.

Answer 30

17.04 Tuesday 17th October 1989 
During evening rush hour
6.9 on Richter Scale
Epicentre in mountainous part of Santa Cruz
3,757 injured
12,000 homeless
Property cost $10 billion

Question 31

Define preparedness and give an example

Answer 31

How ready governments and communities are to respond to a tectonic hazard
E.g. Warning systems, emergency plans, training for rescue teams

Question 32

Define mitigation and give an example

Answer 32

Measures taken to reduce the effect or impact of a hazard

E.g. Moving people away, strengthen buildings

Question 33

Summarise the Montserrat volcanic eruption.

Answer 33

Dormant eruption 1995-1997
Violent eruption - very viscous lava, pyroclastic flows, gases,avalanches
Evacuation of area - small island
Population reduced from 10,500 to just 4,000 people

Question 34

Summarise the Laki volcanic eruption.

Answer 34

Most devastating eruption in human history 1783-4
Part of Mid Atlantic Ridge (Iceland)
Poisonous gases, not explosive
Livestock lost
Half population killed by famine
Reduced global temperatures in Europe

Question 35

What do aid packs usually include?

Answer 35

Canned food
Tents
Mobile field kitchens
Antibiotics
Blankets
Prefab toilets

Question 36

How are building strengthened for tectonic hazards in the developed world?

Answer 36

Cross bracing
Strong flexible joints
Heavy appliances fastened down
Resistant reinforced framework
Supported diagonal steel beams
Base isolator with shock absorbers
Deep foundations made of layers of steel and elastic synthetic rubber
Shear wall and core made from concrete steel rods

Question 37

How are existing buildings strengthened for tectonic hazards in the developing world?

Answer 37

Thick walks
Through stones binds wall together
Wire mesh and cement overlay at wall corners
Timber frame
Cross bracing
Band of concrete stop wall moving outwards
Removal of mud overlay on roof

Question 38

How are new buildings strengthened for tectonic hazards in the developing world?

Answer 38

Cement and sand mortar shaped stones for walls
Concrete ring beam at roof level
‘Knee braces’ - timber frame reinforced
Limit thickness of mud overlay on roof to 200mm