tectonics Flashcards

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1
Q

volcano primary hazards

A

-gas
- ash
- lava
- volcanic bombs
- earthquakes

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2
Q

volcano secondary hazards

A
  • hunger : crops are destroyed therefore nothing to eat
  • homelessness
  • disease
  • flooding
  • deaths
  • unemployment
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3
Q

impacts of earthquakes happening during the day

A
  • more people at work or commuting : families separated
    BUT : can see thats happening
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4
Q

impacts of earthquakes happening at night

A
  • its dark : you cant see whats going on
  • therefore difficult to access damage and find the route to safety : cant find emergency kit
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5
Q

impacts of earthquakes happening during summer

A
  • warmer : shelter is in sun
  • warmer temps higher risk of disease : decomposing bodies
  • can get dehydrated
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6
Q

impacts of earthquakes happening during the winter

A
  • colder temps : need warmth, warm food, blankets
  • much lower risk of diseases
  • less risk of dehydration
  • but more risk of getting killed from the cold
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7
Q

what to have in your emergency earthquake kit

A
  • water : 4 litres per person
  • food - nonperishable
  • flashlight
  • lanterns
  • AM/FM radios : battery operated
  • batteries
  • dusk masks : one for each family member
  • paper money : electricity will be down
  • toiletries
    first aid kit
  • clothes and blankets
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8
Q

active volcano

A

eruption can be anytime and often

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9
Q

dormant

A

has been a while since it has erupted but could at any time

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10
Q

ectinct

A

hasn’t erupted in a very long time therefore probably wont ever

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11
Q

volcano structure : main vent

A

the weak point in the earths crust where hot magma has been to rise from the magma chamber and reach the surface

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12
Q

volcano structure : secondary vent

A

produce secondary cones on the flank of the volcano

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13
Q

volcano structure : crater

A

a bowl or funnel shaped depression that usually lies directly above the vent from which volcanic material is ejected

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14
Q

volcano structure : magma chamber

A

The location beneath the vent of a volcano where molten rock (magma) is stored prior to eruption.

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15
Q

volcano structure : layers of ash

A

alternating layers (strata) of lava, ash, cinders, blocks, and bombs

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16
Q

volcano structure : ash cloud

A

A cloud formed from tiny ash particles and gases blasted from the volcano.

17
Q

volcano structure : volcanic bomb

A

a mass of partially molten rock (tephra) larger than 64 mm (2.5 inches) in diameter, formed when a volcano ejects viscous fragments of lava during an eruption

18
Q

volcano structure : lava flow

A

streams of molten rock that pour or ooze from an erupting vent

19
Q

volcano structure : pyroclastic flow

A

a hot (typically >800 °C, or >1,500 °F ), chaotic mixture of rock fragments, gas, and ash that travels rapidly (tens of meters per second) away from a volcanic vent or collapsing flow frontend

20
Q

layers of the earth

A

1: inner core, 2: outer core, 3: mantle , 4: crust

21
Q

what are conventional currents

A

plates move because of convectional currents, the core heats up the magma, making it rise, cool and sink. the heated magma rises through the mantle

22
Q

how do the convectional currents work

A

1: the outer core is very hot therefore making it rise
2: but since the mantle is less hot , when the magma reaches the top of the mantle it cools down , sinking back down
3: the magma intrution into an oceanic ridge pushes the plates away
4: the magma falls down but gets reheated and the cycle repeats

23
Q

what are destructive plate boundaries

A

the plates move towards each other

24
Q

what are constructive plate boundaries

A

the plates move away from each other

25
Q

what are conservative plate boundaries

A

plates slide past each other

26
Q

what are composite volcanoes

A

1: infrequent but explosive eruption
2: steep slopes + narrow base
3: lava cools close to the vent
4: layers of thick ash + lava
5: secondary cones

27
Q

what are shield volcanoes

A

1: frequent but non-violent eruptions
2: low rounded peak
3: lava is runny so cools far from vent
4: wide base + gentle slopes

28
Q

how do destructive plates create volcanic eruptions

A

1) is where the oceanic and continental crust are moving together
2) the dense oceanic crust sinks ( subduction ) under the lighter continental crust
3) the oceanic is melted and deformed under the friction, pressure and heate created by the subduction
4) the molten rock might rise through the crust as hot magma leading to violent volcanic eruption if released, the friction and pressure created creates powerful earthquakes

29
Q

how do constructive plates create volcanic eruptions

A

1) this is where the plates move away, this normally happens under oceans
2) convection currents pull away from each other, as they do, some creaks and fractures from between plates and there is therefore no solid connection
3) magma may force itself up through the cracks to fill the void, if it makes it to the surface it will for a volcano
4) as a result of this , new land is created

30
Q

how do convectional plates create earthquakes

A

1) this is where two plates slide past eachother side by side, they normally move in a horizontal direction at different angles or speeds
2) due to the different speeds and rough sides, they tend to get stuck or locked together, creating a building of pressure
3) as one plate suddenly slips past the other, this pressure is released and will lead to an earthquake
4) no crust is made or destroyed during this

31
Q

the formation of a composite volcano

A

1) at destructive boundaries the oceanic crust subducts underneath the continental
2) after 70km of subduction the rock starts to melt and magma rises to the surface
3) through this long 70km the magma has a lot of contact with the surrounding rock and absorbs silica from them
4) as the magma rises it has to pass through 70km of continental curst
5) once the magma arrives at the surface cools and dull of silica, this means magma cannot escape and so pressure builds up into an explosive eruption
6) lava and ask is thrown up and falls close to the crater creating a tall, steep sided volcano

32
Q

the formation of a shield volcano

A

1) at constructive boundaries the ocean crust is pulled apart by convection currents
2) when this happens the mantle below depressurises which allows magma to rise towards the surface
3)the magma only needs to pass 10km of basaltic crust
4) the thin curst and low silica basalt means the magma does not absorb much silica
5) after the magma arrives at the surface, it is still very hot and low in silica so a runny lava is produced
6) lava easily escapes, no explosion means little ash. lava flows quickly and cools far from the crater creating low and wide volcano

33
Q

definition of an earthquake

A

the shaking of the ground caused by plate movement