This document provides information about plate tectonics and associated geological phenomena. It begins by describing the layers of the Earth, including the inner and outer core, mantle, and crust. It notes key differences between oceanic and continental crust, and explains convection currents in the mantle. The document then discusses plate boundaries and associated hazards like earthquakes and volcanoes. Specific topics covered include the 2011 Japan earthquake and tsunami, the Montserrat volcanic eruption, measuring earthquakes, predicting seismic activity, earthquake proofing, and responses to natural disasters. Comparisons are drawn between responses to disasters in rich and poor countries.

1. Restless Earth

2. Quick Starter …
Can you name a volcano (as well as its location),
that despite having over half of it submerged in
water, is taller than Mt Everest?

3. Mauna Loa (Hawaii)
You wouldn’t think so but it is 17,000 metres
high … That’s two Everest’s on top of each other.
We can only see 4000 metres – which is just
under half the size of Everest … However, it goes
down another 5000 metres to the sea floor …
Finally it is depressed underneath the sea bed
another 8000 metres.

6. Layers of the Earth

7. • The inner core is in the centre and is the hottest
part of the Earth. It is solid and made up of iron
and nickel with temperatures of up to 5,500°C.
With its immense heat energy, the inner core is
like the engine room of the Earth.
• The outer core is the layer surrounding the inner
core. It is a liquid layer, also made up of iron and
nickel. It is still extremely hot, with temperatures
similar to the inner core.

8. • The mantle is the widest section of the Earth. It
has a thickness of approximately 2,900 km. The
mantle is made up of semi-molten rock called
magma. In the upper parts of the mantle the
rock is hard, but lower down the rock is soft and
beginning to melt.
• The crust is the outer layer of the earth. It is a
thin layer between 0-60 km thick. The crust is
the solid rock layer upon which we live.

9. Types of Crust

10. Oceanic Crust Vs Continental Crust
Oceanic – Dense, 5km thick, Made of Basalt.
Continental – Lighter, 30km thick, Made of Granite

11. Convection Currents

12. How They Work
The core heats the molten rock in the mantle – to
create convection currents.
Heated rock from the mantle, rises to the surface
At the surface the current moves the tectonic plates
in the crust.
Molten rock cools and flows back to the core.

13. Quick Question …
State 3 differences between
oceanic and continental crust?
(3 Marks)

14. Answer
Oceanic crust is lighter than continental crust.
(1 Mark)
Continental crust is 25 km thicker than oceanic.
(1 Mark)
Oceanic crust is made from basalt where as
continental crust is made from granite.
(1 Mark)

15. Plate Boundaries

16. Destructive Plate Boundary
For example – Nazca Plate and South American
Plate.
Two Plates collide, one plate (oceanic) subducts
underneath another (continental)
Many earthquakes and volcanoes are seen here.

17. Constructive Plate Boundary
For example – Eurasian and North American
Plate.
Convection Currents pull crust apart, forming a
volcanic ridge.

18. Conservative Plate Boundary
For Example – San Andreas Fault, California.
Two Plates slide past each other.
Earthquakes happen.

19. Quick Question …
Describe what happens at a
Destructive Plate Boundary?
(4 Marks)

20. Answer
The Oceanic crust subducts underneath the
Continental Crust.
(1 Mark)
This causes an earthquake or can trigger volcanic
eruptions.
(1 Mark)
An example of this is the earthquake in 2011, Japan
when the Eurasian Plate met the Pacific Plate.
(2 Marks)

21. Volcanoes
Shield and Cone Volcanos

23. Shield Volcanoes
• For example – The Mauna Loa
• Found on Constructive Plate Boundaries.
• Gently sloping sides and a wide base.
• Erupt frequently but not violently.
• Contains low silica and gas content.
• Thin runny lava which flows a long way before
solidifying.

24. Cone Volcanos
• For Example – Mt St Helens
• Found on Destructive Plate Boundaries.
• Sticky lava and ash which don’t flow far.
• Steep sides and a narrow base.
• High silica and gas content.
• Erupt infrequently but violently, including
Pyroclastic Flows.

25. Measuring Earthquakes

26. Richter Scale
Measures energy released. The magnitude
increases by x10 each time you go up. So 5 is 10
times more powerful than 4, it also releases 30
times more energy. Another way of saying this is
that it is logarithmic.

27. Mercalli Scale
Measures effects or impacts of the earthquake.
Measured in Roman Numerals from 1 – 12.

28. Quick Question …
Explain what a Pyroclastic Flow is?
(3 Marks)

29. Answer
• A pyroclastic flow is a fast-moving current of
hot gas and rock which reaches speeds moving
away from a volcano of up to 400 mph.
(1 Mark)
• The gas can reach temperatures of about 1,000 °C.
(1 Mark)
• Pyroclastic flows normally hug the ground and
travel downhill. Their speed depends upon the
gradient of the slope.
(1 Mark)

30. Difficulties of Predicting Earthquakes
and Eruptions.
We do not know …
• When it will happen
• Where it will happen
• How big it will be
• How many people live there
• What other impacts it will have

31. What Can Help Us Predict …
• GPS – Satellites detect movement as small as 1mm.
• Satellites that measure infra red radiation look for
any sudden changes in heat.
• Tiltmeters measure small changes in landscape.
• Increase in Smaller earthquakes could be a sign of a
larger one on its way.
• Cameras on rim of crater detect rising magma or an
increase in visible gas.
• Sulphur levels increasing could be a sign of an
upcoming eruption.

32. Earthquake Proofing Buildings
• Installing a band of concrete to the roof to stop
walls falling outwards.
• Very strong framework.
• Strengthen walls.
• Foundations made from steel and rubber - so the
building sways slightly with the quake.
• Digging deeper foundations - more stability.
• Reinforce gas and water pipes so they don't break.

33. What is needed after an Earthquake?
• Trained volunteers to help injured and clear
debris.
• Clean water to prevent spread of disease.
• Gathering food, shops can be damaged.
• Radio communication, phone lines could be
damaged.
• Medical help to care for the injured.
• A plan to evacuate.

34. Quick Question …
Describe 2 ways in which buildings
are earthquake proofed?
4 Marks

35. Answer
• Foundations are not only dug deeper but are made
from steel and rubber, so instead of collapsing it
sways slightly with the quake.
(2 Marks)
• Also bands of concrete can be installed at the top
level of the building to stop walls falling outwards.
(2 Marks)

36. Case Study : Montserrat Volcanic
Eruption
• 1995 when it erupted.
• Dormant since 17th century.
• Eruption sent out large amounts of ash and
lava, including pyroclastic flows.
• Over half the population left the island.
• Whole island was affected

38. Effects
• Destruction of islands crops.
• 19 people killed.
• Destruction of forests ignited by gases from
the volcano.
• Half the original population never returned.
• Plymouth has become a ghost town,
businesses have relocated elsewhere.
• 1 hospital destroyed and airport closed.

39. Responses
• Everyone from the south part of the island
was evacuated.
• Compensation from Britain.
• Monitoring station set up.
• Injured were rescued.

40. Comparing Two Case Studies

41. Japanese Earthquake and Tsunami
• Friday 11th of March 2011.
• 9.2 on the Richter Scale.
• Struck Japanese coast, 20 miles below Pacific
Ocean.
• Pacific Plate subducted underneath the
Eurasian Plate … A Destructive Plate Boundary.
• High magnitude and shallow focus created a
tsunami.

43. Effects
• 40ft waves battered Fukashima nuclear reactors.
Despite being turned off and able to cool down the
reactors exploded. This left this part of Japan highly
exposed to radiation.
• Killed about 16000 people and damage costs stood at
$300 billion. 4.4 million house-holds were left without
electricity. Also 300,000 people were left with nothing,
classed as refugees.
• Tsunami reached Hawaii and Alaska but by then waves
were only 2 metres high, whilst in Japan they were 40
metres high. The Earthquake tilted Earth’s axis and
made the North East, Japanese coastline drop 2 metres.

44. Responses
• There were volunteers from the Red Cross who helped emergency
services.
• US sent out soldiers to Japan to help clear debris and retrieve injured
and dead.
• Other countries donated money, such as the US and Britain.
• Compensation given out to those left homeless.
• Farms were cleared, so business could resume and food could
continue to be produced.
• Shelters were made for injured and homeless.
• People fled before Tsunami which reduced chance of death.
• There were emergency texts sent round all phones seconds before
the earthquake and minutes before the tsunami.
• Supply kits were available before and after the earthquake in case of
an extreme aftermath.
• Because earthquake drills were followed a large number of people
kept their lives.

45. Sichuan Earthquake
• 6AM, May 12th 2008
• 7.8 on the Richter Scale.
• The energy source of the Sichuan earthquake
came from the strike of the Indian Plate onto
the Eurasian Plate and its northward push –
Conservative Plate Boundary

47. Effects
• 900 children died in school.
• Buildings fell down and Dams were damaged,
• 10 million people affected and 70000 dead.
• 80% of buildings collapsed, Roads blocked and
phone lines fell down
• 1 year on and things still have got no better.

48. Responses
• Army were deployed to search for people.
• Evacuations took place.
• Took 3 days for army to get there.
• Aid from other countries.
• 90 helicopters looking from above.
• Community stuck together, worked as a team.
• Cost of repair – 75 billion.
• 1 million temporary homes built for homeless.
• People used hands and shovels to dig people out.

49. Quick Question …
Discuss the different responses to a
natural hazard in a rich and poor
country?
(6 Marks)

50. Answer
In a rich country such as Japan, which suffered an earthquake of 9.2 on the
Richter Scale and killed 16000 people has much better responses compared to
a poor country, (Only in provinces such as Sichuan) China, where there was an
earthquake in Sichuan Province that was measured at 7.8 which killed 70000
people.
Firstly, In Japan there were texts sent around to every phone, warning
of an earthquake, which allowed them to evacuate.
Secondly, the army was instantly deployed to help people after the
earthquake, which would stop the death rate from rising.
Thirdly, japan had better technology, they could dig people out of
rubble using high tech machinery.
On the other hand, in China, they didn’t have good equipment – they
had to dig people out of rubble using there own hands and shovels, by the
time they would get them out they would probably be dead.
Next, there was a very slow response from the army, it took them 3
days to get to the emergency area
Finally, 1 year on, some houses are still not rebuilt and people are still
living in temporary homes.

51. Topics such as Liquefaction and the formation of a
tsunami will not, normally come up on your tests …
However, for added interest …
Liquefaction – Soil becomes liquid, holes in the ground
are created and this can sink buildings. An example of this
happened in Christchurch, New Zealand.
Tsunamis are created when there is an earthquake or
eruption at sea. The movement of the plates makes the
sea bed rise up … so does the water. This creates two
blocks of water which move away from each other in
opposite directions as huge waves.