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Georgraphy > Term 1 - Restless earth > Flashcards

Term 1 - Restless earth Flashcards

1
Q

What is the inner core?

A

The centre and the hottest part of the earth.

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2
Q

What is the inner core made from?

A

Iron and nickel.

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3
Q

Whats the hottest the inner core can get?

A

5500’C

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4
Q

What is the outer core?

A

Surrounds the inner core with a liquid layer.

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5
Q

What is the outer core made from?

A

Iron and nickel.

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6
Q

What temp is the outer core?

A

Similar to inner core.

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7
Q

What is the mantle?

A

The widest section and surrounds the outer core.

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8
Q

How wide is the mantle?

A

2900km

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9
Q

What is the mantle made from?

A

Semi molten rock (magma).

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10
Q

Whats the difference between the top and bottom of the mantle?

A

The top is harder and bottom is soft and melting.

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11
Q

What is the oceanic crust?

A

Thin part of the crust under the ocean.

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12
Q

Whats some properties of the oceanic crust?

A

Heavier than continental, denser, can be subducted (sink), newer than continental (200 million years).

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13
Q

What is the continental crust?

A

Thick part of the crust on the land.

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14
Q

What are some properties of the continental crust?

A

Less dense, Cannot be subducted (sink), older - 1500 million years.

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15
Q

What plates are there?

A

North American, Nazca, South American, African, Eurasian, Antarctica, Indo - Australian and Pacific.

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16
Q

What another word for crust?

A

Lithosphere.

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17
Q

What is asthenosphere?

A

Convection cells anywhere underneath the mantle.

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18
Q

How do volcanoes occur at destructive margins?

A

The oceanic plate moves toward the continental plate and subducts, being melted by magma. This creates pressure on the magma forcing it to rise and break through the continental plate causing an eruption. The reason the plates move together are because of the convection currents in the mantle. The oceanic crust is subducted as it is denser.

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19
Q

How do earthquakes occur at conservative margins?

A

Margins slide past each other in a similar direction at slightly different angles and speeds. As one plate is moving faster than the other and in a slightly different direction, they tend to get stuck. Eventually the build up of pressure causes them to be released. This sudden release of pressure causes an earthquake.

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20
Q

How do volcanoes occur at constructive margins?

A

The less dense magma rises. Convection currents in the magma forms underwater volcanoes and the lava creates a mid - ocean ridge (eg. Mid - Atlantic ridge). Over a period of time volcanic islands may form as the mid - ocean ridge breaks through the surface of the water.

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21
Q

Where do ocean trenches form?

A

Destructive subduction margins.

22
Q

How do fold mountains form?

A

Geosynclines are huge depressions found naturally on the ocean floor. Oceans deposit sediment into these geosynclines and the sediments are compressed and turned to sedimentary rocks like limestone. The plates are forced together at destructive margins (can be subduction or collision). Sedimentary layers are forced upwards into fold mountains.

23
Q

How do people use the Alps?

A

For mining because the folding of sedimentary rocks result in minerals and precious metals coming to the earths surface. They use the V - shaped valleys to produce HEP (Hydro electric power) . They also use the Alps for tourism, cycling in the summer and skiing in the winter. This creates a steady income throughout the year.

24
Q

What properties does a composite volcano have?

A

It is made from andesite lava and is explosive. It has sticky lava and high viscosity. It also has a high silica content and are found at destructive boundaries. They are also cone shaped because of magma getting stuck.

25
Q

What properties does a shield volcano have?

A

It is made from basaltic lava and are non explosive. It has runny lave and low viscosity. It is gentle sided and found at constructive plate boundaries.

26
Q

Whats a VEI?

A

Volcanic explosivity index.
Basaltic eruptions - VEI 0-3
Andesite eruptions - VEI 4-7
Super eruption - VEI 8

27
Q

How can volcanoes be monitored?

A

A seismograph can detect earthquakes which often cause eruptions. A digital camera can view any change to a volcano through sight. GPS systems use satellites to detect movements as little as 1mm. They also detect temperature change.

28
Q

What is a supervolcano?

A

A huge volcano in a giant circular valley called a caldera. Beneath there is a giant pool of molten rock called a magma chamber. This is what erupts because its close to the surface it heats up mud and water which is called geotheramal activity. the huge hot magma chamber creates boiling mud, steam vents called fumeroles and hissing springs called geysers.

29
Q

CASE STUDY

What are the causes of Mount Saint Helen’s eruption?

A

18th May 1980 at 8.32. The earthquake measuring 5.1 on Richter Scale caused a landslide on the north east side of the mountain. The eruption is measured at VEI (volcanic explosivity index) of 5.

30
Q

CASE STUDY

What were the primary affects/impacts of the Mount Saint Helen’s eruption?

A
  • the lateral blast creates a 27km wipe out zone. Whole forests are uprooted by the blast. Some of the cedar forests were over 500 years old.
  • the army is called in to search for survivors. Helicopters rescue many people.
31
Q

CASE STUDY

What were the secondary affects/impacts of the Mount Saint Helen’s eruption?

A
  • trees are blown over by the blast.
  • 57 people were killed.
  • the ash clogged air conditioning systems and blocked roads with drifts a metre deep in places.
  • 250 homes, 47 bridges, 15 miles of railway and 185 miles of highway were destroyed.
32
Q

CASE STUDY

What were the immediate responses of the Mount Saint Helen’s eruption?

A
  • America declares state of emergency.
  • a 8km exclusion zone is set up to stop people getting too close to the volcano. Yet this was ignored by local residents and press.
  • 2 million gas masks were given out to residents across the Washington State.
  • all planes flying across North America are grounded.
33
Q

CASE STUDY

What were the long term responses of the Mount Saint Helen’s eruption?

A
  • high tech equipment used by volcanologist such as COSPEC (Correlation Spectrometer) was used to measure sulphur dioxide. Fumaroles release sulphur dioxide (which turns the surrounding ground yellow). Before eruptions the levels of sulphur dioxide increases dramatically.
  • seismographs were used to detect the tremors and earthquakes in the ground. Patterns can be identified in seismographs to help predict future volcanic events.
  • boreholes measure water temperature as magma heats it up. The hotter the magma the more likely an eruption.
  • USA Geological Survey now closely monitors the volcano.
34
Q

What is an example of a supervolcano?

A

Yellowstone which erupted 640,000 years ago. If it were to erupt again the eruption would 10 times bigger Mount Saint Helen’s. Also the temperatures around the world would decrease and it would affect everyone on the world for years.

35
Q

EXAM QUESTION

Describe the distribution of earthquakes around the globe (4 marks).

A

Earthquakes occur on the west coast of North America on the North American plate. On the west side of South America there are huge clusters of earthquakes. There are clusters all around Australia but more on the east and north sides.

36
Q

What is the focus?

A

It is where the pressure is released.

37
Q

What is the epicentre?

A

It has the highest amount of energy and is always above the focus.

38
Q

EXAM QUESTION

How does the Richter Scale measure earthquakes (3 marks)?

A

The more intense the earthquake, the higher the number. The scale goes from 1-10 and when it goes up one number it means the earthquake is 10 times more destructive.

39
Q

CASE STUDY

What is the general information for Kobe?

A

17 January 1995
7.2 magnitude
Phillippine subducting under Eurasion plate reactivated out fault Nojima fault line running through Kobe CBD
22 seconds where there was solid rock but over 2 min on less solid land

40
Q

CASE STUDY

What are the primary affects for Kobe?

A

Over 6,000 died, many more injured
Infrastructure destroyed (buildings, offices, factories, houses, and port facilities)
Hanshin Expressway collapsed. Older suburbs suffered extensive pancaking due to heavy typhoon proof roofs
Liquefaction in Osaka Bay

41
Q

CASE STUDY

What are the secondary affects for Kobe?

A

Gas mains broke, so fires broke out
Many survivors in temporary accommodation suffered hypothermia as it was the middle of winter
Over 700 aftershocks in the days following. Some companies were forced to close e.g. Mitsubishi.
The port was put out of action for 3 months - reducing the imports and exports trade for the area.

42
Q

CASE STUDY

What were the immediate responses for Kobe?

A

Thermal image equipment, listening equipment and sniffer dogs used to locate trapped bodies. Powerful equipment (jaws of life) lifts debris off survivors.
Effective medical services treat the injured rapidly.
3,000 army troops sent to the areas of Hanshin and the older suburbs.

43
Q

CASE STUDY

What were the long term responses for Kobe?

A

Retro-engineering (on Osaka Bay tower) building spacing, rubber shock observers and reinforced steel rods added to Hanshin government emergency funds help rebuild roads, power supplies and buildings.
Home insurance means people can pay to rebuild their homes.

44
Q

CASE STUDY

What is the general information for the Port au Prince earthquake?

A

13 January 2010
Port au Prince, Haiti, Caribbean
7.0 magnitude
Conservative boundary - Caribbean plate sliding past North American plate. Reactivated a fault line running almost directly under the capital Port au Prince so the epicentre was focussed on the most densely populated parts of the country.

45
Q

CASE STUDY

What was the primary affects of the Port au Prince earthquake?

A

1 in 3 buildings collapse

Prisons broke open, upto 4,000 criminals escaped

46
Q

CASE STUDY

What was the secondary affects of the Port au Prince earthquake?

A

Nearly 250,000 died. Many more injured. Violence followed as the society in Haiti descended into chaos. Social unrest, looting and rape were all reported. 1 million living in camps in January faced hypothermia. Infrastructure destroyed. Cholera killed many.

47
Q

CASE STUDY

What were the immediate responses of the Port au Prince earthquake?

A

Aid was slow to arrive - the port was inaccessible for 5 days and the airport for 2 days. Responses from the UN and NGOs was slowed and hampered by social unrest, violence and fear. The UN and NGOs were afraid of entering the city. Haitians argued the UN was more concerned with arming and protecting its soldiers. Only 1 ambulance for the entire city. Emergency services not mobilised. Only 130 people pulled from the rubble alive and survivors left to search for loved ones themselves. Many dead laid unburied, decomposing on the streets.

48
Q

CASE STUDY

What were the long term responses of the Port au Prince earthquake?

A

Haiti one of the poorest countries in the world. Government has very little funds. City not rebuilt up to 2 years later. Many of the millions given to NGOs (like Red Cross) as aid did not end up helping survivors. Up to 1 million people still having to live in tents in refugee camps a year after earthquake. Many die from cholera in the hurricane season 10 months.

49
Q

CASE STUDY

What are the factual details of the earthquake and tsunami in Japan?

A 
11 March 2011 at 5.46 GMT
9.0 magnitude
Epicentre: Sendai, Japan
10m high tsunami wave generated
5th largest earthquake ever
50
Q

CASE STUDY

What caused the earthquake and tsunami in Japan?

A

Japan is located on destructive margin
The plates stick, tension builds up. When this pressure builds up and is released, it causes a rapid shift in the plates and the sea floor thrusts up.
The earthquake was 9.0 on the Richter Scale, it was a mega thrust earthquake.

51
Q

CASE STUDY

What were the affects on the people in Japan?

A

The currency - the Yen - fell sharply. Tokyo stocks fell. The 10m high tsunami hit at various places along the coast, destroying ports and coastal industries. Fukushima nuclear power plant automatically shut down. Bridges collapsed and a building was washed away, with boats and cars swirling around. 15,000 people confirmed dead, 530,000 people displaced, 4,700 destroyed houses, 50,000 damaged houses. Coastal areas flooded and power outages to 4 million houses.

52
Q

CASE STUDY

What have been the responses to the tsunami in Japan?

A

50 workers asked to stay to prevent radiation leakage.
Tsunami warning issued 3 mins after earthquake.
Metereological Agency official appeared on TV urging those affected by the quake not to return home.
Japanese military forces sent into help.

Georgraphy (8 decks)

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