Geo Tectonics Topic 1 Flashcards
(58 cards)
1
Q
Describe Oceanic-Oceanic Divergent Plate Boundary
A
- Two oceanic plates move away at divergent plate boundary.
- The decrease in overlying pressure causes underlying mantle material to melt, forming magma
- Magma becomes less dense rises from weak areas in the crust to the earth’s surface, fill the gaps cause by spreading plates.
- Lava cools and solidifies forming basaltic rocks.
- Basaltic rocks make up new oceanic crust.
- An extensive underwater mountain chain-the mid oceanic ridge forms.
- At the centre of the ridge is a deep rift valley with steep sides,
- The magma rises through weak areas in the crust to the earth’s surface forming submarine volcanoes.
- After eruptions, the volcanoes break the surface of the ocean to form volcanic islands
- The tension and stress when two plates move causes earthquake.
2
Q
C-C divergent plate boundaries
A
- Two continental plates move apart
- The rocks eventually form parallel faults
- The rocks between the faults collapses to form deep rift valley with steep sides.
- As plates move apart, the decrease in overlying pressure causes the underlying mantle to melt, hence forming magma.
- Magma become less dense and rises through the weak areas in the crust to the earth’s surface, forming volcanoes.
- earthquake occurs because of the stress and tension when two plates move apart.
3
Q
O-O convergent plate boundaries
A
- Two oceanic plates collide
- The denser oceanic plate subducts beneath the less dense oceanic plates.
- The depression when one plate subducts under another forms oceanic trench.
- As subducting plate sinks to the mantle, the high pressure forces the water out of its oceanic trench and the water lowers the melting point of the overlying mantle, causing it to melt, forming magma.
- Magma rises from weak areas in the crust to the earth’s surface, forming a chain of volcanoes and volcanic island.
- Friction along the subducting plate causes earthquakes to occur.
4
Q
C-C convergent plate boundaries
A
- Two continental plates collide.
- There is no subduction taking plate because continental plate are too buoyant to subduct.
- Enormous pressure causes the rocks to be uplifted and buckled to form fold mountains.
- Friction slong the convergent plate boundary causing the earthquake to occur.
- Magma does not rise to surface, hence there is no volcanoes occur.
5
Q
O-C convergent plate boundaries
A
- The oceanic plate collide with continental plate.
- The denser oceanic plate subducts beneath the less dense continental plate.
- The depression when one plate subducts beneath another form oceanic trench in the subduction zone.
- As the subducting plates sinks to the mantle, it forces the water to come out of the oceanic trench, the water lowers the melting point of mantle, causing the mantle material to melt, forming magma,
- Magma rises from the weak areas in the crust to the earth;s surface,, forming a chain of volcanoes or volcanic island.
- The friction along the subducting oceanic plate causes earthquak to occur.
- The high pressure of the plate boundary causes the rocks to be uplifted and buckled forming fold mountain
6
Q
Transform plate boundary
A
- Stress causing the plate movement produces a fault, hence is a zone of fractures.
- Since one plate suddenly slide past another, it forms earthquake.
- There is no magma rising, hence no volcano
7
Q
Example O-O divergent plate
A
Ocean North American plate
Oceanic Eurasian plate
8
Q
Divergent C-C
A
Nubian Playe
Somalian Plate
9
Q
Convergent O-O
A
Pacific Plate
Phillippines plate
10
Q
Convergent C-c
A
Indian Plate
Eurasian Plate
11
Q
Convergent O-C
A
Nazca Plate
South American Plate
12
Q
TRansform
A
nORTH AMERICAN PLATE
pacific plate
13
Q
divergent plate boundary leads to volcano
A
- Two plates move apart
- Overlying pressure causes underlying mantle to melt, forming magma.
-Magma contains dissolved gas, it is less dense than the surrounding material, - Magma rises from the weak area in the crust to the earth’s surface to erupt lava, causing volcanic eruption
-Lava cools, solidifies and accumulates forming volcano
14
Q
convergent plate boundary leads to volcano
A
-Two plates move towards each other.
-Denser plates subducts beneath less dense plate
-The subducting plates sink into the mantle, the high pressure forces forces the water out of the oceanic crust. Water lowers the melting point of the mantle, causing mantle to melt, forming magma
- Because of the dissolved gas inside magma, it is less dense and hence rises from the weak area of the crust towardsthe earth’s surface causing volcanic eruptions
- Lava cools and solidifies and accumulates over time, forming volcanoes
15
Q
Strato volcano
A
high viscosity magma rises through weak areas in the crust to the earth surface and erupts explosively as rocks, ash, and lava
rocks and ash settle on the side of the volcanoes while lava covers on top of them.
- Sucessive eruptions
=> A tall volcano with alternating layes of rocks and lava firns,
strato volcano travels shorter distance before colling and solidify
= volcano: steep sides+ narrow summit
16
Q
Shield volcano
A
-Low viscousity magma rises through weak areas in the crust to the earth’s surface and explose effusively
Over successive eruptions, volcano consist of layers of lava develops
-less viscous lava travels a longer distance before cooling and solidifying, hence it has gently slope and broad summit
17
Q
e.g of strato volcano
A
Mount Mayon in the Phillipines
18
Q
e.g of shield volcano
A
Kilauea(Hawaii, USA)
19
Q
what is earthquake
A
Earthquake is the shaking of earth’s ground due to the sudden release of the energy in the earth’s lithosphere
20
Q
the process forming earth quake
A
- The rock masses on either side of a fault were pushed by tectonic processes.
- Friction causes them to get locked and build up tension.
- When the tension exceeds the limit of the rocks, the rocks will be snap or suddenly move to a new position.
- This sudden movement causes seismic waves which result in ground shaking
21
Q
What is a focus?
A
A focus is the point in the earth’s crust that is near the seismic waves
22
Q
epicentre
A
the point on the earth’s surgace directly above the focus
23
Q
How do divergent plate boundary result in volcanic eruptions?
A
- Two plates move apart.
- The overlying pressure when two plates move apart causes the underlying mantle to melt, forming magma.
- Magma contained dissolved gas, hence it is less dense than the surrounding materials.
- It rises through the weak areas in the crust to the earth’s surface, it then erupt as lava,forming a volcanic eruption.
- The lava cools, solidifies and accumulates over time, forming a volcano
24
Q
How do convergent plate boundary contributes to volcano?
A
- When two plates collide, the denser plate subducts beneath the less dense place.
- As the denser plate sinks into the mantle, the high pressure forces the water out of oceanic crust, the water causes the mantle to have lower melting point, hence it melts, forming magma.
- Magma contains dissolved gases, hence it is less dense than the surrounding materials.
- Magma rises through weak areas in the crust to the earth’s surface to erupt as lava, forming volcanic eruptions.
- As the lava cools, solidifies and accumulates over time, forming volcano
25
When does volcano form?
The volcano forms when lava erupts the earth's surface
26
When does stratovolcanoes form?
Stratovolcanoes form when high viscosity magma rises through weak areas in the crust to the earth's surface, erupts explosively as lava, dust and ash
27
When does shieldvocalnoes form?
Shield volcano forms when:
- low viscosity magma rises through weak areas in the crust to the earth surfaces and erupts effusively.
-Over successive eruptions, volcano consisting of layers of lava develops
- Less viscous Lava travels a longer distance before cooling and solidifying, volcano have gently sloping sides with a broad summit
28
Ground shaking earthquake nature
- Nature:
+ Ruptures oil and chemical factories,polluting lands and forests.
+ Uproot trees, causing widespread treei injurity and damaging wildlife habitats.
29
Soil liquefication form when?
-Soil liquefication occurs when the violent ground shaking disrupt the soil structure of saturated loose soil, making it transform into a thick fluid.
-
Example: 2010-2011 Christchurch Newzealand:
-City lies on swamp area, hence trigger a severe liquefication
-More than 60000 residental buildings and infrastructure were damaged.
-Liquefied soil enter water pipes which pollutes the rivers, causing reduction in some of the species like caddisflies
30
Landslides earthquake definition+ nature+ example
- Landslides occur when the creaks on steep slopes lossening the rocks and soils, causing it to move down the slopes.
- Nature:
+ A large amount of debris destroys forests and wetlands, hence cause a loss in biodiversity
- A large amount of debris pollute the rivers, killing aquatic species.
- Rivers can be blocked, causing flood, damaging nearby ecosystems and properties.
31
Tsunami forming?
Tsunami was caused because:
-Underwater earthquake caused the seabed to be displaced.
- A large volume of water is lifted, forming waves of greate wavelength and low height of less than 1m.
- The waves move at high speed of about 800km/h and it slows down when it appoarching the coast because of the friction with shallower seabed.
- The waves get closer together and increase in height. Waves can be 15m or more, and it moves at a speed of about 30-50km.
- Before tsunami occur, the sea may recede from the coast as it fills in the void cause by displacement of seabed.
32
Tsunami affecting human ?
- Human system:
+ Infra:
- Fast-moving waters that carried a large amount of debris sweep buildings, house and infrastructure away, destroying them
- Services:
+ Fast-moving water carried a large amount of debris sweep communication and electricity cables , gas and water pipes away, disrupting these services.
- The railways and roads were sweep away by fast-moving waters making it difficult to rescue and supply people with emergency aid.
- Fatalities:
+ Fast-moving waters carried a large amount of debris hit and kill people, causing loss of lives.
+ People were drown my the sweeping waters
2004 Indian Tsunami
More than 230000 people were killed
33
Tephra volcano
- Nature:
+ Ash can be carried thousands of kilometers away by prevailing wind, polluting a huge areas of forests, rivers and other habitats, destroying ecosystem.
+Ash suffocate and kill wildlife
+Ash will cause blindness to birds as their eyelids are gummed together
- Human:
+ Infrastructure:
+ Volcanic bombs size can be range from cm to a vehicle, it can hit and destroy buildings and infrastructure.
+ Ashfall on buildings' roof.
+ Ash can be twice as heavy when mixed with water.
+ Ash can be corrosive, hence destroy building structures, making them more likely to collapse.
+ Thick blankets of ash can damage farmlands, suffocate crops, destroy livelihoods.
- Services:
+ Damaging plane engines, causing disruption to air transportation services, causing closer of airspaces.
+ People:
+ Ash can cause respiratory problems, eye irritation and suffocate people.
- Volcanic bombs cause injuries, loss of life.
1991 Mount Pinatubo eruption in Phillipines
-Detroyed 800km of rice paddy, affecting livelihoods of farmer.
- buried 180km of forests in ash of about 25cm.
34
Volcanic gases nature
Nature:
+ Sulfur dioxide mixed with water n air form acid rain which damage vegetation, soil and kill wildlife.
+high content of carbon dioxide in air kill wildlife, and damage vegetation.
+ Carbon dioxide is heavier than air, it can become concentrated in low-lying volcanic are (rift valley)
35
soil liquefication impacts on nature
Nature:
+ The trees on liquefied soil sinks in and tip over, damaging wildlife habitats, causing forest and biodiversity loss.
+ Liquefied soil may enter the rivers and smother aquatic plants causing them to die.
+Sewage pipes may be broken and untreated waste material may pollute rivers, killing aquatic species.
36
soil liquefication impact on human system
Human:
+ Infrastructure:Buildings and other infrastructure sink in liquefied soil making it tip over and collapsed, the damage making it difficult to rescue or supply people with emergency aid
+ Services:
- Roads and railways above liquefied soil sink in and get damaged, making it difficult to rescue or supply people with emergency aid.
- Water and gas pipes, electricity and communication cables sink in and get snap, disrupting these services.
+Fatalities:
People under collapsed buildings and infratructure resulting in loss of lives or injuries.
37
groundshaking human
- Human:
+ Infrastructure:
Weakens buildings, bridges, road and railways, making it difficult to rescue or provide emergency aids to people.
+ Services:
-Cause communication and electricity cable to break, affecting important communication services like tsunami warning or television broadcast.
- Snaps water and gas pipes, causing water shortage, disrupting gas supply.
+ Fatalities:
-People may get trapped in collapsed buildings and infrastructures, resulting in loss of life and injuries.
38
groundshaking examples
example: Haiti, 2010
- Water pipes reuptured=> water shortage
- over 220000 people were killed,
- more than 250000 house collapsed because of violent shaking.
-surroungding areas around factories were polutted.
- debris polluted riverss
39
landslide human
Human:
+ Infrastructure:
- A large amount of debris can bury villages and farms, destroying properties and infrastructures.
+ Communication:
- Water and gas pipes were damaged, causing a shortage in water and gas supply.
- Break electricity and communication cables, disrupting the services.
-Blocked roads and railways making it difficult to rescue and supply people with emergency aids.
- fatalities:
+ Debris can bury people under collapsed buildings, causing injuries and loss of lives.
+ Floods can drown people.
40
tsunami affecting nature system
- Nature:
+ The sea water flood over a huge areas of coatal wetlands and forests, damaging biodiversity.
+ Large amount of debris carried by the waves can pollute these areas, damaging ecosystems, killing wildlife.
41
volcanic gases human+eg
Human
Infra:
Sulfur dioxide can react with water in air, forming acid rain that corrode buildings and infrastructure.
Fatalities:
-Sulfur dioxide causes eye, skin, and throat irritation.
-air contains more than 3% of carbon dioxide=> headaches+ breathing difficulties
- Air contains more than 15% carbon dioxide=> death
e.g: Dieng Volcano erupt in Indonesia in 1979, release deadly amount of carbon dioxide=> kill 150 people
42
lava flows
- Nature
- Human:
Infra
services
43
pyroclastic
44
lahars
45
volcanic landslides
46
benefits volcano
47
short-term hazard
48
long-term hazard
49
poverty
50
lack of acess to piped water
51
proximity to dry/ sea area
52
mitigation MNFNCCC
53
mitigation clean energy
54
mitigation clean resources
55
mitigation carbon technology
56
mitigation
57
adaptation
58
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