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Tectonic Hazards Flashcards

1
Q

Oceanic crust

A

Quite thin (5-10km thick), very dense, subducts, so it’s continually destroyed

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2
Q

Continental crust

A

Very thick(30-50km thick), not very dense, never subducts, so can’t be destroyed

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3
Q

Tectonic plate

A

It’s slab of rock made up of Earth’s lithosphere

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4
Q

Earthquake

A

It’s sudden or violent movement within Earth’s crust followed by series of shocks

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5
Q

Volcano

A

It’s opening in Earth’s crust from which lava, gases + ash erupt from

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6
Q

Plate Margins/Boundaries

A

They’re place where tectonic plates meet

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7
Q

Crust

A

It’s Earth’s outermost layer, consists of tectonic plates, upper part of lithosphere + lies above mantle

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8
Q

Mantle

A

It’s layer of silicate rock between crust + outer core, it’s largest layer + upper mantle is bottom part of lithosphere

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9
Q

Convection Currents

A

It’s movement of magma within Earth’s mantle caused by heat of core + it causes hot magma to rise as it’s less dense + then fall, currents flow beneath lithosphere, which builds up lateral pressure + carries plates with them

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10
Q

Ridge Push

A

It happens at constructive margins, oceans ridges form above ocean floor, magma heated by core rises, rising magma reaches lithosphere + cools down to form plate material, as it cools, it forms new plate material, which forces plates apart

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11
Q

Slab Pull

A

At destructive margins, denser oceanic plate subducts into mantle due to gravity, which pulls rest of plate behind it

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12
Q

Outer core

A

It’s made up of liquid iron + nickel, it surrounds inner core + it’s below mantle

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13
Q

Inner core

A

It’s Earth’s innermost layer, it’s extremely hot (it can reach temperatures of up to 5500ºC) + is made up of solid iron + nickel

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14
Q

Destructive boundary

A

It’s when tectonic plates move towards each other, denser oceanic plate subducts beneath continental plate, friction builds up between them, causing very strong earthquakes, as oceanic plate moves downwards, it melts, creating magma, which is thicker than at constructive boundary + breaks through surface, forming steep-sided composite volcanoes (stratovolcanoes) e.g Pacific + Eurasian Plate

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15
Q

Pyroclastic flow

A

It’s flow with mixture of steam, ash, rock + dust

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16
Q

Constructive boundary

A

It’s when tectonic plates move away from each other, magma forces it’s way through overlying crust to surface + breaks through it, causing very small, non-violent earthquakes, magma is very hot + fluid, so lava erupting from broad + flat volcanoes, with gentle but frequent volcanic eruptions, will flow long way before cooling + tectonic plates move apart by ridge push e.g South American Plate + African Plate

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17
Q

Conservative boundary

A

Plates move past each other or parallel to each other at different speeds, friction between moving plates causes destructive earthquakes, which are released when plates slip + shift, they happen along conservative boundaries as stresses build up over many years e.g Pacific + North American Plate

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18
Q

Distribution of earthquakes + volcanoes

A

Most happen at plate boundaries (constructive, destructive + conservative)

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19
Q

Focus

A

Place inside Earth’s crust where pressure is released from earthquake

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20
Q

Epicentre

A

Point of Earth’s surface directly above focus

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21
Q

Magnitude

A

Strength of earthquake

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22
Q

Intensity

A

Measure of violence of earth movement due to earthquake

23
Q

Seismic Waves

A

Shockwaves produced by earthquakes in Earth’s crust

24
Q

New Zealand: Primary effects

A

7,000 injured, 100,000 buildings damaged, water + sewage pipes damaged

25
New Zealand: Secondary effects
US $40 billion worth of damage, 10,000 homeless, 10,000 people left Christchurch
26
New Zealand: Immediate responses
US $7 million received in aid, temporary housing provided, zoning of areas to assess damage + safety
27
New Zealand: Long term responses
10,000 affordable houses built, water + gas pipes reconnected, buildings demolished, repaired + rebuilt
28
New Zealand: Causes
Earthquake in Christchurch - 375,000 people, so 1,300 people per square km, Focus - very shallow (5km), Richter Scale Strength - 6.3, Conservative plate boundary, HIC, 22nd February 2011 - 12:50 am
29
Seismometer
Device that records seismic waves
30
Nepal: Causes
Earthquake 80km north-west of capital city Kathmandu, 1,200,000 people, so 20,200 people per square km, Focus - 15km below epicentre, Richter Scale Strength - 7.9, Destructive plate boundary (two continental plates), LIC, 25th April 2015 - 11:56am
31
Nepal: Primary effects
3 million left homeless, cost of damage $5 billion, 7,000 schools destroyed
32
Nepal: Secondary effects
Landslide that blocked Kali Gandaki River, avalanche on Mount Everest - killed at least 19 people, avalanche in Langtang region, which left 250 people missing
33
Nepal: Immediate responses
Financial aid pledged from many countries, 500,000 tents needed to provide shelter for homeless, Helicopters rescued many people on Mount Everest
34
Nepal: Long term responses
$ 200 million from US in aid from Asian Development Bank, over 7,000 schools to be rebuilt or repaired, Repairs to Mount Everest base camp
35
Reasons for people choosing to live in areas at risk from tectonic hazards: Geothermal energy
In volcanically active areas it’s major source of energy - renewable, so it reduces greenhouse gases emitted, reducing climate change + it won’t run out, e.g Hellisheidi geothermal power plant, Iceland, Environmental
36
Reasons for people choosing to live in areas at risk from tectonic hazards: Farming
Brings more people + money to area, therefore, buildings built to high standards of earthquake resistance, Soil is fertile due to volcanic eruptions, e.g California, Irrigated fields of crops, Economic
37
Reasons for people choosing to live in areas at risk from tectonic hazards: Mining
Settlements develop where valuable minerals are found as jobs are created in mining industry, e.g Mining sulphur at Kawasaki Ijen crater, Indonesia, Economic
38
Reasons for people choosing to live in areas at risk from tectonic hazards: Tourism
Tourist bring money to area which benefits economy, e.g Geysers at Rotorua, New Zealand, Economic
39
Reasons for people choosing to live in areas at risk from tectonic hazards: Family, friends and feelings
Can see your friends + family more often than if you were to move away from them, e.g Ankara, Turkey, Social
40
Monitoring
Recording physical changes e.g tracking tropical storm by satellite or using scientific methods to study coastal processes to help inform management options
41
Protection
Actions taken before hazard strikes to respond to reduce its impact e.g education people or improving building designs
42
Planning
Actions taken to enable communities to respond to + recover from natural disasters e.g producing hazard map
43
Prediction
Using historical evidence + monitoring, scientist can make predictions about when + where tectonic hazards may happen
44
Monitoring: Earthquakes
Scientists can predict where earthquakes usually happen by using historical maps to see where earthquakes have happened before, earthquakes happen on fault lines (cracks in rocks)
45
Protection: Earthquakes
Buildings: Deep foundation into solid rock, weights on roof to counterbalance shaking, several emergency staircases + exits to speed up evacuations
46
Planning: Earthquakes
Maps can be produced to show effects of earthquake or to identify areas most at risk from damage so that high value land e.g hospitals can then be protected in these vulnerable areas
47
Prediction: Earthquakes
Impossible to predict
48
Monitoring: Volcanoes
Ground deformation: changes to shape of volcano are measured using laser beams, remote sensing: satellites detect heat + changes to volcano’s shape, geophysical measurements: detects changes in gravity as magma rises to surface
49
Protection: Volcanoes
Earth embankments + explosives can be used to divert lava away from property although not much can be done due to sheer power of volcanic eruption
50
Planning: Volcanoes
Hazard maps can be produced + they show likely areas to be affected, they can be used to restrict certain land uses or to identify which areas need to be evacuated when eruption is about to happen
51
Prediction: Volcanoes
Based on scientific monitoring
52
Volcanoes at a Destructive Plate Margin: Steep-sided composite volcanoes (Stratovolcanoes)
They’re made up of alternating layers of lava + ash, they have pyroclastic flows + they have very violent volcanic eruptions
53
Lithosphere
It’s made up of Earth’s crust + upper mantle

Geography (6 decks)

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