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Full geog > Plate tectonics (KQ2) > Flashcards

Plate tectonics (KQ2) Flashcards

1
Q

What are some examples of tectonic landforms?

A
  • fold mountains
  • rift valleys and block mountains
  • volcanoes
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2
Q

How are fold mountains formed?

A
  • they are formed along convergent boundaries
  • compressional force creates immense pressure
  • this causes rocks to buckle and fold
  • increasing compressional force on one limb may cause it to fracture and ride over the other limb
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3
Q

What are some examples of fold mountains?

A
  • Himalayas
  • The Andes
  • The Rockies
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4
Q

How are rift valleys formed?

A
  • they are formed at divergent plate boundaries
  • tensional forces cause parts of the plate to fracture
  • this forms faults
  • as the plates are further pulled apart, a central block of land will sink between a pair of parallel faults to form a rift valley
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5
Q

How are block mountains formed?

A
  • they are formed at divergent plate boundaries
  • tensional forces cause parts of the plate to fracture
  • this forms faults
  • as the plates are pulled apart, land masses surrounding a block of land will sink to form a block mountain between a pair of parallel faults
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6
Q

What are some examples of rift valleys?

A
  • East African Rift Valley
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7
Q

Where are volcanoes found?

A
  • covergent + divergent plate boundaries
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8
Q

How are volcanoes formed?

A
  • magma rises from subduction zones which accumulates in magma chamber where pressure builds up
  • it then forces its way up onto the earth’s surface through vents (lava)
  • lava builds up around the vent, solidifying to form a small crater (volcanic cone)
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9
Q

What happens during an eruption?

A
  • during an eruption, lava, ash and rock fragments are released
  • the force of the eruption depends on the amount of pressure and gas in magma
  • summit may also be blown off during an explosive eruption
  • sides of the crater collapse inwards due to the loss of structural support, creating a large depression
  • lava covers the ash layer and builds up the volcano again
  • during the formation, the vent may be blocked
  • thus, this forces the magma to find a new exit route (secondary cones)
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10
Q

What are the 2 types of volcanoes

A
  • stratovolcano
  • shield volcano
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11
Q

What does the type of volcano depend on?

A
  • type of lava
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12
Q

What is the difference between the two types of lava?

A
  • shield volcanoes, which have low-silica lava have less viscous lava
  • stratovolcanoes, which have high-silica lava have more viscous lava
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13
Q

What are the characteristics of shield volcanoes?

A
  • low-silica lava
  • they have gentle slopes + broad summits
  • lava does not trap as much gas, which leads to less explosive eruptions
  • successive eruptions increase the size of the volcano as lava accumulates
  • common near divergent plate boundaries, such as Mt Washington, USA
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14
Q

What are the characteristics of stratovolcanoes?

A
  • high silica lava
  • they have steep slopes + narrow summit
  • developed from successive eruptions of lava + ash
  • after initial eruption, the subsequent eruptions eject lava which covers the soft ash and prevents it from being eroded away
  • over time, a high volcano with a slightly concave profile develops
  • secondary cones may also develop from vent seeps at the sides and erupt
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15
Q

Other than lava, what else is ejected during an eruption of a stratovolcano?

A
  • pyroclastic flows
  • these are hot rock fragments + superheated gases
  • they move down the slope of the volcano at high speeds
  • lahars
  • they are a mixture of pyroclasts + melted ice
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16
Q

What are earthquakes?

A
  • vibrations in the earth’s crust caused by a sudden release of stored energy
  • energy released in the form of seismic waves
  • found in rocks along plate boundaries and fault lines
17
Q

What is an earthquake made up of?

A
  • seismic waves
  • focus
  • the focus is a point of sudden energy release
  • epicenter
  • the epicenter is the point on the earth’s surface directly above the focus
  • aftershocks
  • aftershocks are smaller earthquakes that occur after the initial earthquake as a result of stress within crusts
18
Q

Where is the location of the focus?

A
  • deep focus: 70-700km below earth’s surface
  • shallow focus: <70km below earth’s surface
19
Q

What impact does focus have on land?

A
  • deep focus:
  • smaller impact
  • longer traveling time of seismic waves which leads to less energy
  • shallow focus:
  • large impact
  • shorter traveling time of seismic waves leads to more energy
20
Q

What are the factors that affect the impact of an earthquake?

A
  • magnitude of earthquake
  • population density
  • level of preparedness
  • distance from epicentre
  • time of occurrence
  • type of soil
21
Q

How does population density affect the impact of an earthquake?

A
  • densely populated urban areas are more likely to be more heavily impacted by an earthquake compared to less densely populated rural areas
22
Q

How does level of preparedness affect the impact of an earthquake?

A
  • having evacuation plans, trained rescue workers and action plans can reduce the damage done by earthquakes
23
Q

how does the distance from the epicentre affect the impact of an earthquake?

A
  • it affects the strength of the earthquake in the area
  • this affects the damage done to the area
  • the closer an area is to the epicentre, the more likely that it will sustain more damage
24
Q

How does the magnitude of an earthquake affect the impact of an earthquake?

A
  • it affects the strength of the earthquake
  • for example, stronger earthquakes cause more damage than weaker earthquakes
25
Q

How does time of occurence affect the impact of an earthquake?

A
  • when an earthquake occurs at night, when people are unconscious, they cannot react and carry out the emergency plans as quickly as during the day
26
Q

How does type of soil affect the impact of an earthquake?

A
  • loose and unconsolidated soil can cause liquefaction of the ground
  • this can cause damage especially to buildings
27
Q

What is a tsunami?

A
  • a tsunami refers to a large sea wave
28
Q

How are tsunamis formed?

A
  • the movement of the seafloor during a large earthquake at the subduction zones
  • an underwater volcanic eruption
  • an underwater landslide
  • a landslide above sea level that causes materials to plunge into the sea
29
Q

What are some benefits to living near volcanic areas?

A
  • fertile volcanic soil
  • precious resources
  • tourism
  • geothermal energy
30
Q

Why is fertile volcanic soil a benefit of living near volcanic areas?

A
  • lava + ash from volcanic eruptions break down to form fertile soil that is favorable for agriculture
31
Q

What are some examples of fertile volcanic soil?

A
  • volcanic soils of Java and Bali have been able to support large rural populations for decades
32
Q

Why are precious resources a benefit of living near volcanic areas?

A
  • volcanic rocks can produce precious stones and materials
  • diamonds are formed in volcanic pipes due to intense heat and pressure
  • can sell this stuff for money
  • brings about economic growth
33
Q

What are some examples of volcanic areas with precious resources?

A
  • diamonds are mined from old volcanic rocks in Kimberly, South Africa
34
Q

Why is tourism a benefit of living near volcanic areas?

A
  • volcanic areas provide a variety of activities such as hiking, camping sightseeing and some even have historical value
  • more tourists = more money
35
Q

What is an example of tourism in volcanic areas?

A
  • the ruins of Pompeii, Italy which was a city buried in layers of ash by mt Vesuvius, a volcano in 79 CE
36
Q

Why is geothermal energy a benefit of living near volcanic areas?

A
  • geothermal energy refers to heat derived from the earth’s crust
  • groundwater in contact with hot rocks underground heats up and erupts as hot water or steam
  • this is then harnessed to drive turbines
  • this then produces electricity
  • more environmentally friendly source of energy
37
Q

What is an example of geothermal energy near a volcanic area?

A
  • 70% of Iceland’s domestic heating is produced by geothermal energy

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