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geography 1 > restless earth > Flashcards

restless earth Flashcards

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1
Q

What four layers make up the earth?

A

crust, mantle, inner core and outer core

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2
Q

what’s the difference between the Oceanic and Continental crust?

A

The Oceanic is newer, most less than 200 million years old. it is also denser than continental crust and can be subducted (sink). It can also be renewed and destroyed.

The Continental crust is older with most over 1500 million years old. It is also less dense than oceanic and cannot be subducted (sink). It cannot be renewed and destroyed.

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3
Q

What is a plate margin?

A

The boundary where two plates meet

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4
Q

What is subduction?

A

When a ocean plate sinks below a continental

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5
Q

Describe destructive subduction?

A

The Oceanic plate moves into and subducts beneath continental plate. ( Juan de Fuca Plate (Oceanic) subducts beneath North American Plate (continental)).

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6
Q

How are ocean trenches formed? Include a named example?

A

Deep sections of the ocean, usually where an oceanic plate is sinking below a continental plate. Mariana Trench, in the Pacific, is the deepest part of the planet where two oceanic plate are being subducted.

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7
Q

Name an example of a Tsunami?

A

Japanese tsunami had a megathrust of 9.0, destructive subduction in the Pacific Ocean, epicentre in Sendai, Japan, 10m high tsunami wave.

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8
Q

What is a drawback?

A

The withdrawal of the ocean minutes before the tsunami hits land.

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9
Q

A tsunami train is?

A

The series of waves that hit the coast during a tsunami.

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10
Q

What is a megathrust?

A

When the crust is forced upwards by an earthquake above 9.0 on the richter scale. The Asian and Sendai tsunamis were megathrust events.

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11
Q

Definition of a tsunami?

A

A wave where the entire depth of the sea or ocean is set in motion by and event, often an earthquake, which displaces the water above it and creates a huge wave.

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12
Q

What is convection currents?

A

The circular currents of heat in the mantle.

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13
Q

What is a plate?

A

A section of the earth’s crust.

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14
Q

Destructive collision is?

A

Where two continental plates move together to form fold mountains e.g. Indo-Australian Plate (Continental) collides with the Eurasian Plate(Continental) to form the Himalayas.

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15
Q

Constructive is?

A

Where two plates move away from one another. If two oceanic plates move apart shield volcanoes form to create islands. e.g. north American plate and Eurasian plate.

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16
Q

What is Conservative?

A

Where two plates slide pass one another, locking together and often jolting together to form earthquakes. Volcanoes do not form at this margin.

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17
Q

Young Fold Mountains are?

A

Large Mountain Ranges where rock layers have been crumpled and forced upwards as they have been forced together at destructive margins.

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18
Q

Geosynclines is?

A

Huge valley’s where sediments are deposited by rivers and the sea. Layers of rock build up in Geosynclines and it is these layers that are forced upwards to form young fold mountains.

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19
Q

What is Europe’s highest Young Fold Mountain Range?

A

The Alps

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20
Q

Transhumance is?

A

Movement of livestock up and down the mountain.

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21
Q

What is HEP?

A

Hydro-electric Power

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22
Q

Multiplier effect is?

A

As one business grows in the area so do other businesses that are connected to it e.g. Skiing, shops, restaurants, equipment, campsites

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23
Q

Mining is relatively easy because?

A

The Alps have been folded out of the crusts, forcing out metals, minerals and fossil fuels to lie relatively close on the surface.

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24
Q

What are composite volcano’s?

A

A steep sided volcano that is made up of a variety of materials such as lava and ash. the lava is viscous (sticky) which helps to create steep side. Eruptions can be pyroclastic e.g. Mount Saint Helens

25
Q

Shield Volcano is?

A

A broad, gently sloping volcano that is composed of lava which is non-viscous(non-sticky) which means that the sides are gentle. e.g. Mauna Loa

26
Q

What is a natural hazard?

A

A natural disaster where people have no control and poses threat to life and possession’s.

27
Q

A vent is?

A

An opening to volcano from which magna is erupted.

28
Q

What is magma?

A

Molten rock found within the earth’s crust.

29
Q

Lava is ?

A

Magma that has come out of the crust through a vent and been oxidised.

30
Q

Pyroclastic floe is?

A

The build up of pressure under a lava dome can turn lava, ash and dust into a gaseous mix. when the lava dome erupts this then moves rapidly through the air and down the volcano side at 200mph. the temp is over 200 degrees Celsius.

31
Q

Lava dome is?

A

The plug at the top of the volcano that traps lava beneath.

32
Q

A crater is?

A

A large open-faced area around the vent at the top of the volcano.

33
Q

What is a Lahar?

A

A secondary effect that is a volcanic mudflow. ash mixes with rainwater/snowmelt to form huge flows of mud e.g. St Helens.

34
Q

What is a primary effect?

A

Immediate effect of an eruption or earthquake caused directly by it.

35
Q

What is a secondary effect?

A

The after effects that occur as an indirect effect of the eruption on a longer timescale.

36
Q

A ring of fire is?

A

A ring of volcanoes that circle the pacific ocean. This includes the west coast of North and South America and Indonesia.

37
Q

What is immediate and long term responses?

A

The reaction of people after a natural hazard has taken place. Immediate responses include emergency services, whilst long term involve building and construction.

38
Q

Positive effects of volcanic eruptions include?

A

Fertile soil (supporting farming and food supplies), increase in tourism. Geothermal energy-release of heat .
volcanic lava cools to create precious gems such as diamonds, opals and quartz.
Recreation activities, skiing, hiking and walking.
House hold products ( Pumice released by eruptions) e.g. kitty litter, toothpaste and stonewashed jeans.

39
Q

What is USGS?

A

United States Geological Survey (who survey and monitor volcanos)

40
Q

GPS is?

A

Global Positioning Systems- uses satellite’s to detect earth movement as little as 1mm. Some installed at St Helens.

41
Q

What is lava dome deformation?

A

Changes in the lava dome happen just before eruption.

42
Q

Name different ways to detect eruptions

A

Tiltmeters which identify small changes in landscape caused by shifting magma beneath.
Digital cameras which are heat resistant.
COSPEC which measures sulphur dioxide release. More Sulphur is released just before eruption.

43
Q

What is a Fumaroles?

A

Opening s on a volcano that releases sulphur.

44
Q

What is a seismograph?

A

A measuring device rigged to a sensor recording the seismic activity by plotting movement with a pen on a rotating drum.

45
Q

A seismogram is?

A

The line graph that is printed out by the seismograph patterns can be observed and predictions made.

46
Q

A super volcano is?

A

A mega volcano that erupts at least 1,000km3 of material. They erupt less than normal volcanoes but when they erupt they can be incredibly destructive. They are found away from plate boundaries on top of hot spots. E.g. Yellowstone

47
Q

What is a caldera?

A

The depression of the super volcano makng the collapsed magma chamber.

48
Q

Fissures are?

A

lines of weakness that allows magma to escape.

49
Q

Geothermal features are?

A

Natural features that are created by a magma chamber close to the surface. For example, a geyser is a superheated jet of water that is forced out of the crust under pressure.

50
Q

What is a hot spot?

A

A section of the earths crust where plumes of magma rise weakening the crust. They are away from plate boundaries.

51
Q

Earthquake is?

A

A build up of pressure within the earths crust. this is suddenly released and the ground shakes violently.

52
Q

A focus is?

A

The point in the crust where the pressure is released and where seismic waves come from. Shallow focus quakes are move destructive.

53
Q

What is the epicentre?

A

The point on the crust directly above the focus. It receives the highest amount of energy.

54
Q

what are seismic waves and name all three?

A

The energy released by an earthquake.
P waves- Primary waves are the fastest waves and shake the earth backwards and forwards.
S waves- Secondary waves are slower and move with a side ways motion.
Surface waves- Travel nearer the surface and most slowly. They arrive at the end, but are most destructive. They can be longitudinal and transverse.

55
Q

Magnitude is?

A

The amount of energy that is released by an earthquake usually measured on the richter scale.

56
Q

Richter scale is?

A

Represents the strength of the earthquake. It is scientific and reliable but doesn’t recognise the effects of the earthquake.

57
Q

The Mercalli scale is?

A

A 12 point scale that measures the effects of a seismic event which is based on peoples observations and not scientific.

58
Q

What are the 3 P’s?

A

Prediction, protection and preparation
Prediction- Attempts to forecast an event (USGS)
Protection- Construct buildings so they are same and will not collapse.
Preparation- Organising activities and drills so people will know what to do in case of an earthquake.

59
Q

What is a megathrust?

A

When the crust is forced upwards by an earthquake above 9.0 on the richter scale.

geography 1 (6 decks)

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