Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Geography > Walton- plate tectonics > Flashcards

Walton- plate tectonics Flashcards

You may prefer our related Brainscape-certified flashcards:
U.S. Geography flashcards World Geography flashcards
1
Q

What is a constructive plate boundary

A

when two plates move apart, diverge, both oceanic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a destructive plate boundary

A

two plates move towards each other (converge) oceanic plate is denser so subducts under continental.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is extrusive volcanic activity

A

This takes place on the earths surface.

The major form of this activity is volcanic eruptions of lava and other material.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Lava eruptions

A 
Lava eruptions are a form of extrusive activity.
There are three types of lava; 
Balsaltic
Andesitic 
Rhyolitic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Basaltic Lava explanation

A
  • Made a constructive plate boundary
  • Low silica content
  • low viscosity- therefore lava flows easily and gases
    easily therefore eruptions aren’t violent.
  • Temp of 950
  • Eruptions are frequent and occur for long periods of time.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Andesitic and Rhyolitic Lava

A

These have a high viscosity and therefore lava flows less easily and often forms blockages in volcanic vents. Gasses can’t escape easily.
Pressure builds up due to blockages and trapped gas until blockages are cleared by violent eruptions.
Erupts once in a while and are shore lived.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

EXTRUSIVE ACTIVITY Composite volcano

A 
Major form of extrusive activity. 
steep slopes
Made up of alternating layers of ash and lava
Lava has high gas pressure and explosive
consists of andesitic and rhyolitic lava
occur at destructive plate boundary 
E.g Mount Rainier
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

EXTRUSIVE ACTIVITY Shield Volcanoes

A 
Major form of extrusive activity.
gentle slopes
formed by frequent, gentle eruptions of thin runny basaltic lava.
occur at constructive plate boundary 
Mauna Loa
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

EXTRUSIVE ACTIVITY Fissure Volcano

A

Occur at constructive Plate boundary
gentle slopes
Fissure vent- few M wide and many KM long
made up of basaltic lava- high temp low gas
eruption type- has a linear volcanic vent through which lava erupts usually without any explosive activity.
occur at constructive plate boundary

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

EXTRUSIVE ACTIVITY Acid/ dome volcano

A 
Roughly circular mound shaped volcano 
steep convex slopes from thick fast cooling lava 
Destructive PB 
andesitic and rhyolitic lava 
violent eruptions- high gas pressure
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

EXTRUSIVE ACTIVITY Caldera volcano

A

central part of volcano has collapsed due to the magma chamber below being emptied.
caldera rim
Destructive pb
andesitic and rhyolitic lava
violent eruptions- gass trapped- exploisive
YELLOW STONE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Minor extrusive activity

A

Geysers
Solfatara
Boiling mud
Fumaraloes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is Geysers

A

Geysers are discharges of water from the vents in the earths surface.
They are caused by superheating of water in the magma chambers below the ground surface.
The hot water becomes pressurised causing it to eventually explode onto the surface through cracks.
Erupts periodically when pressure has built up and is dangerous
YELLOW STONE NATIONAL PARK

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are solfataras

A

They are mounds of sulphur deposits that are found on the earths surface where sulphur has precipitated out of the water.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Boiling mud

A

Where mud and hot volcanic water mix causing it to bubble, creating a hot muddy pool

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Fumaraloes

A

Water that turns to stream as the pressure drops as it emerges from the ground.
may occur along tiny cracks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is intrusive volcanic Activity

A

Takes place beneath the earth surface.
It includes the formations of magma chambers and magama being forced into the crust through cracks. When magma cools and solidifies intrusive landforms are created.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Batholiths

A

Formed deep below the ground surface where large masses of magma cool and solidify, when these magma chambers cool underground they form a dome of igneous rock. In which later tors are exposed by either erosion or weathering
e.g Dartmoor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Dykes

A

This is where vertical intrusion occurs as when the magma has flowed into gaps in the surrounding area and cooled, it forms vertical dykes- creates dyke swarms
Here the ridge of rock are more resistant than the surrounding rock.
E.g isle of arran, Scotland

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Sills

A

This is where horizontal intrusion occurs as when the magma has flowed into the gaps and cooled it forms horizontal sills.
E.g North of England.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Difference between Constructive and Destructive

A
  1. Plate margin
  2. type of magma
  3. lava characteristics
  4. type of eruption
  5. material eruped
  6. frequency of eruption type
  7. volcanoes formed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Volcanic hazards

A
  1. Pyroclastic flow
  2. Lahars
  3. Lava
  4. Volcanic Tsunamis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Pyroclastic Flow

A

PRIMARY EFFECT
Pyroclastic flow are high density mixtures of hot dry rock fragments and hot toxic gases moving away from the vent that erupted them at high speeds of up to 100km.

They may result from explosive eruptions of molten or solid fragments of rock or both. or Non explosive activity of lava, when a part of a dome collapses down a steep slope.

Pyroclastic flow consists of two parts.

  1. Basal flow of coarse fragments that move along the ground
  2. turbulent clouds of ash that rise above the basal flow

There are two types of flow that are formed;
1. Nuee Ardentes;
generated from the explosive collapse of a growing lava dome and has dense lava fragments from the dome

  1. Pumice Flows
    are pumic rich pyroclastic flow derived from the collapse of eruption column
    consists of low density puic
24
Q

Effects of Pyroclastic Flow

A

Pyroclastic flow will destroy everything in its path.
Rock fragments range in different sizes from ashes to boulders and travel up to a speed of 80km
Pyroclastic flow will knock down, bury, shatter and cary anything thats in its way.

E.g volcanic eruptions in Merapi 2010

  • Where primary danger was from pyroclastic flows.
  • They generated and reached up to villages 14.5km from volcano.
  • completely destroyed everything within 16km

Extreme temperatures of rocks and gases in the pyroclastic flow causes combustible material to burn, such as petroleum products, wood and houses and vegetation.
E.g Merapi 2220 houses destroyed causing displacement of over 400,000 people
- villages and agriculture buried in up to 30cm of ash= loss of lively hoods.
- 453 people injured as direct result of burns from pyroclastic flows.

Burn people and animals,
Small flows of less than 5km from volcano can destroy buildings and forests.
They generally follow valleys or low lying lands.

25
Q

Lahars

A

SECONDARY EFFECT
Lahars a volcanic mudflow, created when pyroclastic flows mixes with water.
ash and water mix forming a type of mud that sets like cement when it stops flowing.

Water can come from within the volcano or the surrounding areas when it explodes. Also can comes from the snow and ice on the flanks of the volcano.

Lahars normally occur when there is no eruption. Causes are;
Glacial water melted by pyroclastic flow
Heavy rainfall on unsolidified pyroclastic deposits.
volcanic landslides

26
Q

Effects of lahars

A

Lahars are very dangerous as they’re fast flowing up to 10 m/s and 100m deep
Not as hot or fast as other volcanic hazards but are very destructive
bulldoze through things in the way
if collided with structures the buildings give way due to the force creating huge damage.
E.g Chille- Chaiten volcano
violent eruption produced lahars
farming destroyed
lahars cut commucation and made access difficult
rivers and water supplies contaminated.

27
Q

Tsunamis

A

SECONDARY EFFECT
They are huge sea waves (seismic waves)
They are tall in height and have extreme power
reach up to 10m high

There are two ways in which a volcanic eruption can cause a seismic wave.

  1. One possibility is when the land base volcano erupts and breaks down and collapses, forcing large amounts of ash and lava into the water. The sudden changes and displacement of the water column transfers kinetic energy resulting in waves,
  2. Tsunamis are induced by submerged volcanoes. These underground volcanos collapse downwards or spew forth lava heating the surrounding areas quickly.
28
Q

Effects of tsunamis

A

They affect large area of more than 25km.
They typically occur with little warning and can devastate coastal populated areas.
volcanic tsunamis transmit the energy of a volcanic eruptions to great distances producing more devestation that what would originally occur with just the eruption.

E.G One of the most devastating and largest tsunamis recored was on the August the 26th 1883 after the eruption and collapse of the volcano Krakatoa in Indonesia.
Waves occurred up to 135 ft
destroyed towns and villages along sundra strait
killed 36,417 people.

29
Q

Lava volcanic hazard

A

PRIMARY EFFECT
Lava is molten rock flowing out of the ground usually from volcanoes during an eruption
There are three main types of lava
Balsaltic lava
- Made a constructive plate boundary
- Low silica content
- low viscosity- therefore lava flows easily and gases
easily therefore eruptions aren’t violent.
- Temp of 950
- Eruptions are frequent and occur for long periods of time.
- Shield + fissure volcanoes
E.g mauna loa and lake fissure

Andesitic + Rhyolitic lava
- high and medium silica content
These have a high viscosity and therefore lava flows less easily and often forms blockages in volcanic vents. Gasses can’t escape easily from viscious lava
Pressure builds up due to blockages and trapped gas until blockages are cleared by violent eruptions.
Erupts once in a while (intermittently) and are shore lived.

30
Q

Lava volcanic effects

A

National park burns from advancing lava flows

  • everything in the path of an advancing lava flow is knocked over, buried or ignited due to hot temps
  • deaths are uncommon as lava is slow moving so people can move out the way and they don’t travel far.
  • deaths attributed to lava is from explosions of water interacting with lava or from collapse of a active lava delta.
  • buries homes and agricultural land up to 10m of blackened rock.
31
Q

Formation of Fold mountains

A
  1. Fold mountains are the result of either a destructive plate boundary when the oceanic plate is subducted beneath the continenetal at a subduction zone,
    or where two plates move together at a collision zone.
    so occur when two plates move towards each other.
  2. upfold = antisyncline
    downfold = syncline
  3. Erosion carries sediment down the river, the sediment accumulates onto the sea bed and is laid down horizontally.
  4. The geosyncline is the then filled with sediment that is compressed into the rock. Due to the plates move towards each other the ocean floor begins to fold and disappear.
  5. Continued compression from the plate movement causes the sediment to fold into fold mountains due to intense pressure.
32
Q

formation of an ocean trench

A
  1. Occurs at a destructive plate boundary where the denser oceanic crust is sub-ducted beneath the lighter continental crust.
  2. It is subducted deep within the mantle causing the sea floor and lithosphere to bend and form a steep v-shaped depression in the ocean floor.
  3. it marks the point of subduction
33
Q

Formation of Rift valleys

A
  1. Occurs at a constructive plate boundary.
    Convection currents rise and as its rising it forms a dome beneath the plate.
    the currents diverge spreading and dragging the bottem of the plate causing it to stretch
    eventually cracks occur in plate due to pressure.
  2. The diverging of the currents continue to move apart causing the plate to eventually split.
    huge blocks of crust subside due to gravity
    Release of pressure on the mantle enabling magma to form and well up in cracks.
  3. plates continue to move apart and a rift valley occurs in the central part.
    magma from underlying mantle feeds numerous volcanoes and shallow earthquakes occur due to edge of blocks rubbing together.
  4. Injection of magma along the rift valley pushes plates apart-
    now the central rift valley has sunk below sea level and is flooded with water- forms a new ocean.
  5. Magma injected into the rift valley spills over forming a chain of underwater volcanoes and mountains.

E.G east african rift system.

  1. Most distinctive and geological feature in Africa.
  2. Rift opened approx 65million years ago and threatens to split east Africa from rest of continents.
  3. Caused a notheast drift of the arabian plate and opened the rea sea to the indian ocean aswell as caused a volcanic uplift of Africas highest peaks e.g kilamanjaro in Tanzia.
  4. Opened 28ft due to recent earthquake.
34
Q

Island Arcs Formation

A

occurs at a destructive plate boundary with two oceanic plates. Denser oceanic plate is subducted. q

  1. The plates that subducted melts due to friction and the hot core and magma forms due to melted molten rock.
  2. Magma rises and leaks into the crusts creating a series of volcanoes along the ocean
  3. this forms a volcanic island arc.

E.G japanese islands

  1. situated on a subduction zone- in the northwestern margin of the pacific ocean.
  2. where the pacific plate, phillipene sea plate. eurasia and N america plate subducts.
  3. Japanese islands emerged part of the volcanic arcs extending to approx 300km.
35
Q

Hotspot formation

A
  1. Hotspots are the direct result of plumes of magma originating deep within the mantle as radio active elements in the mantle begin to eat the crust.
  2. as balsaltic sheild volcanoes erupt through the drifting ocean crust, they may build up from the ocean floor and form islands.
  3. They become part of the plate and gradually move away from the heat source (hotspot) due to plate movement e.g the pacific plate moves NW
  4. Newer volcanoes erupt from the stationary hotspot and newer islands are formed.
  5. The combined processes of magma formation, eruption and the continuous plate movement over the stationary hotspot all leaves a trail of volcanoes along the ocean floor.
  6. hawaiis main island is closest to the hotspot and therefore is the most active.
  7. Older volcanoes soon become eroded by marine erosion and extinct.
  8. They then from flat top called guyots.
36
Q

Earthquakes

A
  1. Occur at all plate boundaries
  2. Mainly associated with conservative and destructive plate boundary’s
  3. More destructive on destructive plate boundary’s
  4. An earthquake is the result of a sudden release of energy in the earths crust that creates seismic waves.
  5. Earthquakes are recorded with seismometers also seismographs
  6. Intensity of shaking is measured on the mercalli scale (modified) which looks at the level of damage caused. and goes in roman numerals.
  7. Richter scale measures the power in a logarithmic scale.
37
Q

Elastic rebound theory

A
  1. Plates are moving towards eachother not having met yet at their original position
  2. Plates have rough edges so when they move past eachother they become jagged. deformation
  3. Rupture occurs and release of energy. energy is released in waves that radiate outwards from the fault.
  4. Rocks rebound to original undeformed shape.
38
Q

Focus

A

Point within the crust where the earthquake actually happens. The deeer the focus the less destructive it is as the longer distances they have to travel the more energy us lost whilst travelling.

Shallow focus- 0-70km
Intermediate focus- 70 - 300km deep
Deep focus - 300 - 700 km deep

Seismic shock waves have the highest level of energy at the focus- energy decreases as the waves spread outwards.

39
Q

Primary effects of EQ

A
  1. Tsunamis;
  2. landslides and avalanches
  3. ground shaking
  4. faulting and ground ruptures
40
Q

Primary effects of EQ

TSUNAMIS

A
  1. Oceanic subducts beneath, rough plate gets stuck and bends. pressure builds up and projects waves of water when the plates release.
  2. enormous sea waves generated by disturbances on the sea floor.
  3. triggered by earthquakes and submarine landslides.
  4. devestating and recent example = indonesia 2004 which was 100ft in height
41
Q

Primary effects of EQ

LANDSLIDES + AVALANCHES>

A
  1. loose bedding plate (ways rocks are layered)
  2. Where slope failure occurs as a result of groundshaking
  3. More destructive than earthquakes
  4. Residential area in alaska destroyed
42
Q

Primary effects of EQ\

GROUND SHAKING

A
  1. Shaking of the ground caused by passage of seismic waves near the epicentre surface.
  2. Waves are responsible for damaged caused
    - local geology
    - duration and intensity
    - distances from epicentre.
43
Q

Primary effects of EQ

FAULTING AND GROUND RUPTURES

A
  1. When an earthquake occurs, ground rupture is only where the fault zone moves.
  2. structure adjacent to fault survive and structures built across it collapse.
44
Q

Secondary effects of EQ

A
  1. Liquefaction
  2. Human impacts
  3. Damage to man made structures
  4. fires
  5. floods
45
Q

Secondary effects of EQ

LIQUEFACTION

A
  1. violent disruptions of the ground causes it to become liquid like when strongly shaken.
  2. Extreme shaking can reduce the strengh of soil making it easily fall.
  3. Cause cause movement of groundwater.
  4. Excess water can may come up to the surface through cracks bringing liquified soil creating soil volcanoes.
  5. buildings can sink
    e.g San francisco- the ground is more likely to sink due to redevelopment on reclaimed land.
    here 100,000 worth of damaged was caused by 1989 earthquake.
46
Q

Secondary effects of EQ

HUMAN IMPACTS

A
  1. Depends upon the popluation density and distance from the epicentre
  2. Strong shaking of the ground can cause buildings. roads and bridges to collapse
  3. disruption to gas supplies and electricity supplies and fires caused from gas mains = loss of trade.
47
Q

Secondary effects of EQ

DAMAGE TO MAN MADE STRUCTURES

A
  1. Roads and bridges and dams and buildings depend upon the type of construction
    - concrete and masonry structure are brittle and therefore more susceptible to damaged and they collapse
    - damage to wood and steel structures are far less because of its flexibilty.
48
Q

Secondary effects of EQ

FIRES

A
  1. often associated with broken electrical and gas lines
  2. common side effect of earthquakes
  3. Gass is set free as gas lines are broken and spark which will bring inferno
  4. water lines are also broken so theres no water to extinguish the fire.
    e. g San francisco earthquake of 1906 had 90% of damage due to fires.
49
Q

Secondary effects of EQ

Floods

A
  1. Can come from many sources such as broken water main pipes, dams that fall due to earthquakes and tsunamis generated by earthquakes.
  2. When a earthquake breaks the dam or levee the water from the reservoir of rivers floods the surrounding area. this damages buildings and sweeps people away.
  3. Small tsunamis called selches can destroy houses and uproot trees
  4. Earthquakes can also change course of river causing it to flow the opposite direction.
50
Q

the mercalli scale

A
  1. The mercalli scale measures the impacts of the earthquake.
  2. designated by roman numerals
  3. More meaningful measure of severity than magnitude as intensity refers to the effects experienced.
  4. Impacts measured using observations of the event.
    Low numbers = manner in which earthquakes are felt by people
    high numbers = based on observed structural damage.

Disadvantage = Subjective whereas the richter scale has a seismograph an actual instrument to measure power.

51
Q

Richter scale

A
  1. The richter scale measure the magnitude of the earthquake.
  2. it is a logarithmic meaning that an earthquake with the magnitude of 5 has a amplitude (wave sizee) 10 times greater than the magnitude of 4.
  3. The magnitudde is calculated using information gathered by a seismograph.
  4. most people don’t feel earthquakes of magnitude 1-7
    Major earthquakes are above 7.
52
Q

Seismic waves.

A

Definition; an elastic wave in the earth produced by an earthquake or other means.
1. Earthquakes generate 3 types of sesimic waves
P waves, s waves and surface waves.
Both p and s waves penetrate the interior of the earth whilst surface waves do not. So p + s waves are known as body waves
P WAVES
1. Travel though both liquids and solids.
2. They’re known as body waves as they travel through the body of the material.
3. P waves are the fastest seismic waves therefore detected first.
4. travel roughly 6.0km in the crust
5. They are compressional waves and rely on the compressional + elasticity of material to spread
6. As it a longitudinal, wave motion of the material particles that transmit energy move parallel to the direction its spreading.
7. cause the least damage because of the small amplitudes.

S WAVES;

  1. Second wave you feel in an earthquake
  2. S waves is slower than p waves and can only move through solids.
  3. They move up and down or side to side- perpendicular to the direction the wave is travelling in.
  4. More damaging than p waves as they’re several times higher in amplitude.

SURFACE WAVES;
Surface waves in contrast to body waves can only move along the surface.
2. Confined to outer layers and arrive after p+s waves.
3. THey can also cause the most surface destruction.
4. They are divided into two categories love and rayleigh.
LOVE WAVES;
1. have a particle movement which like s waves is transverse to the direction of propagation but with no vertical movement.
2. Their side to side motion causes the ground to twist from side to side.
3. That is why they cause the most damage to structures.

RAYLEIGH WAVES;

  1. Create a rolling up and down motion with an elliptical and are confined to where they’re made.
  2. generally surface waves aren’t generated by deep earthquake.
53
Q

P waves

A

P WAVES

  1. Travel though both liquids and solids.
  2. They’re known as body waves as they travel through the body of the material.
  3. P waves are the fastest seismic waves therefore detected first.
  4. travel roughly 6.0km in the crust
  5. They are compressional waves and rely on the compressional + elasticity of material to spread
  6. As it a longitudinal, wave motion of the material particles that transmit energy move parallel to the direction its spreading.
  7. cause the least damage because of the small amplitudes.
54
Q

S waves

A

S WAVES;

  1. Second wave you feel in an earthquake
  2. S waves is slower than p waves and can only move through solids.
  3. They move up and down or side to side- perpendicular to the direction the wave is travelling in.
  4. More damaging than p waves as they’re several times higher in amplitude.
55
Q

Surface waves

A

SURFACE WAVES;
Surface waves in contrast to body waves can only move along the surface.
2. Confined to outer layers and arrive after p+s waves.
3. THey can also cause the most surface destruction.
4. They are divided into two categories love and rayleigh.
LOVE WAVES;
1. have a particle movement which like s waves is transverse to the direction of propagation but with no vertical movement.
2. Their side to side motion causes the ground to twist from side to side.
3. That is why they cause the most damage to structures.

RAYLEIGH WAVES;

  1. Create a rolling up and down motion with an elliptical and are confined to where they’re made.
  2. generally surface waves aren’t generated by deep earthquake.
56
Q

Formation of tsunamis

A
  1. Occurs on a destructive plate boundary
  2. Where the oceanic plate is subducted
  3. the overriding plate gets stuck and starts to bend and flex.
  4. Pressure build up and the energy is released causing the plate to flick
  5. Column of water displaced is pushed upwards creating a tsunami wave.

Geography (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions