Tectonics

Question 1

How are volcanoes formed?

Answer 1

Magma rises through cracks or weaknesses in the Earth’s crust.
Pressure builds up inside the Earth.
When this pressure is released, eg as a result of plate movement, magma explodes to the surface causing a volcanic eruption.
The lava from the eruption cools to form new crust.
Over time, after several eruptions, the rock builds up and a volcano forms.

Question 2

What is a constructive plate margin?

Answer 2

Two plates move away from each other. Molten rock or magma immediately rise to fill any possible gap and forms a new oceanic crust

Question 3

What is a conservative plate boundary?

Answer 3

Two plates slide next to each other, they can go in the same direction but go at separate speeds.

Question 4

What is a destructive plate margin?

Answer 4

A destructive plate boundary is sometimes called a convergent or tensional plate margin. This occurs when oceanic and continental plates move together. The oceanic plate is forced under the lighter continental plate. Friction causes melting of the oceanic plate and may trigger earthquakes.

Question 5

What is a collision plate boundary?

Answer 5

A destructive plate boundary is sometimes called a convergent or tensional plate margin. This occurs when oceanic and continental plates move together. The oceanic plate is forced under the lighter continental plate. Friction causes melting of the oceanic plate and may trigger earthquakes.

Question 6

Give me the three types of seismic waves

Answer 6

P waves- vertical movements
S waves- horizontal movements
Surface waves- rippling waves

Question 7

How do volcanoes function?

Answer 7

A volcano is formed by eruptions of lava and ash.
Volcanoes are usually cone shaped mountains or hills.
When magma reaches the Earth’s surface it is called lava. When the lava cools, it forms rock.
Volcanic eruptions can happen at destructive and constructive boundaries, but not at conservative boundaries.
Some volcanoes happen underwater, along the seabed or ocean floor.

Question 8

Give me three things that come out of volcanoes

Answer 8

Lahars-mud flows
Ash cloud- toxic
Pyro clastic flows- boiling ash and fire travelling at 200km/hr

Question 9

Give me 3 causes of the Japanese earthquake

Answer 9

The cost of Sendai, was really close to the epicentre
Wednesday the 9th earthquake happened of 7.2
Made the plate margin move at 2.4m and lifted upwards at 9m

Question 10

Give me 3 causes of the Japanese tsunami

Answer 10

Happened 2 days after the earthquake hit
More people died in the tsunami
Came in at 800kph

Question 11

How many casualties of Japan?

Answer 11

Deaths 15,500
Injuries 5,700
Missing 4,800

Question 12

Social effects of the tsunami

Answer 12

32,000 casualties and left people homeless

Question 13

Economic effects of the tsunami

Answer 13

$122 billion to repair
Most manufacturing stopped
Plantations lost 40%

Question 14

Nuclear crisis of the tsunami

Answer 14

Fukushima power plant was hit
killed 50 volunteers
Everyone in a 20km radius most likely to develop cancer

Question 15

What is the crust?

Answer 15

Outer most layer also as the lithosphere

Solid rock split into tectonic plates

Question 16

What are the two types of crust?

Answer 16

• Continental crust: forms land granite, low density, between 30 - 50 km in thickness
• Oceanic crust: under the oceans basalt, more dense, between 6 - 8 km in thickness

Question 17

What is the asthenosphere?

Answer 17

Semi molten upper part of the mantle on which the plates float
Below the lithosphere and 100 - 200 km below the surface

Question 18

What is the mantle?

Answer 18

Composed of rock called peridotite
The top layer is between 75 250 km thick and is partially molten
The bottom layer is around 2200 km thick and is sold

Question 19

What is the outer core?

Answer 19

Around 2300 km thick and composed of iron and nickel

This is liquid

Question 20

What is the inner core?

Answer 20

Around 1000 km thick and composed of iron and nickel

It is solid

Question 21

What are seismic waves, the focus and epicentre?

Answer 21

During an earthquake SEISMIC WAVES move out from the point where the rocks of the tectonic plates move
This point is called the FOCUS
The EPICENTRE is directly above the focus on the earths surface

Question 22

What is the Richter scale?

Answer 22

Measures the magnitude of earthquakes

Question 23

What are primary effects of an earthquake?

Answer 23

The immediate damage that occurs i.e. Collapsing buildings, cracks in roads, death, panic

Question 24

What are the secondary effects of an earthquake?

Answer 24

After affects of an earthquake i.e. Fires, tsunamis, disease, longer term economic impacts

Question 25

When was the Sichuan earthquake?

Answer 25

12 May 2008 | Magnitude 8.0

Question 26

What were the social impacts of Sichuan?

Answer 26

70,000 dead 375,000 injured 5 million homeless

Question 27

What were the economic impacts of Sichuan?

Answer 27

Over 1 million people lost their job due destruction of work places Rebuilding costs estimated around $75 billion 200 large after shocks 27th May magnitude 6.0 caused 420,000 buildings collapsed

Question 28

What are the local responses of Sichuan?

Answer 28

Heavy rain, landslides and aftershocks made the rescue effort difficult: • 50,000 soldiers sent to dig for survivors • helicopter were used to reach the most isolated areas • Chinese people donated $1.5 billion aid

Question 29

What are the international responses to Sichuan?

Answer 29

China quickly asked the rest of the world to help: • some countries sent moment, UK GAVE $2 million • Finland sent 8000 six person tents and Indonesia sent 8 tonnes of medicines • rescue teams flew in from Russia, Hong Kong, South Korea and Singapore

Question 30

give me 3 factors to a composite volcano

Answer 30

- viscous, sticky and thick - steep volcanoes - magma runs slowly, and can freeze through the central vent - infrequent and unpredictable

Question 31

give me 3 factors to a shield volcano

Answer 31

- gentle slopes - lava is fluid - flows quickly - very frequent and generally gentle eruptions

Question 32

how can tsunamis be formed?

Answer 32

large volcanic eruptions or earthquakes can cause a tsunami as a secondary impact series of destructive waves sub-sea earthquakes can displace the sea which can cause tsunamis

Question 33

Explain how the Earths tectonic plates move

Answer 33

High temperature in the core caused by gradual radioactive decay create rising limbs of material in the mantle called convection currents These cool and spread out as they rise before sinking again and some this material moves into sheets creating movements in the crust above it, which is pulled apart to form new crust - in other places it rises as columns, creating hotspots

Question 34

What do the impacts of any hazard, including earthquakes and volcanoes depend on ?

Answer 34

- size of the event - the vulnerability of the population - poverty and high density increase vulnerability - the capacity of the population to cope - how prepared they are

Question 35

What are the different factors that influence a volcano or earthquake?

Answer 35

- because plate margins are essentially lines, so most volcanoes are found in lines - volcanic eruptions generate earthquakes but earthquakes also occur on conservative margins and sometimes happen in regions many thousands of miles from plate margins - not all volcanoes are found on plate margins. Some are found at hotspots where the crust is moving over a column of rising magma

Question 36

How can a tsunami occur?

Answer 36

Large volcanic eruptions and earthquakes can both cause a tsunami as a secondary hazard Tsunamis are a series of very destructive ocean waves Sub-sea earthquakes can displace seabed which causes tsunamis to form The waves travel at speeds up to 900 km/h and when they strike land, waves can be 20-30 m high and flood far inland

Question 37

How can volcanoes be predicted?

Answer 37

- gas emissions, earth tremors and 'bulging' of a volcano's flanks can be measured and used to predict - in 1991 about 120,000 people were evacuated from the area around Mt Pinatubo before it erupted

Question 38

How do you prepare yourself for an earthquake?

Answer 38

- emergency plans, well trained and funded emergency services, warning systems and evacuation routes - reducing impact by mitigation such as hazard resistant buildings, disaster kits and land use planning

Question 39

What are examples of mitigation in a developed world?

Answer 39

Making new buildings better: - foundations very deep but allow movement - shock absorbers built into structure - cross bracing to prevent floors collapsing

Question 40

What are examples of mitigation in a developing world?

Answer 40

Make existing buildings better: - reduce the weight of the roofs - lightweight, hollow bricks used - strengthen wall corners with wire mesh and cement