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edexcel a levek geog🌍 > TECTONIC HAZARDS EQ1🌋 > Flashcards

TECTONIC HAZARDS EQ1🌋 Flashcards

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1
Q

define hazard

A

a perceived natural or geophysical event that has the potential to threaten both life and property.

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2
Q

earthquake case study (1)

A

The nepalese earthquake

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3
Q

when was the nepalese earthquake

A

25th of april 2015

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4
Q

what was the magnitude of the nepalese earthquake

A

7.8

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5
Q

how many injuries and deaths in the nepalese earthquake

A

8633 deaths over 21,000 injuries over 3 million people were made homeless

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6
Q

how much did the nepalese earthquake cost

A

They lost US$5 billion from its GDP (25% of its total) rebuilding cost : US $6.6billion NEPAL WILL NEED TO RELY ON FOREIGN AID

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7
Q

where is nepal located

A

southern asia between india and china . Nepal sits on a fault line between the indian and eurasian tectonic plates.

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8
Q

define a disaster

A

where a natural hazard causes social , environmental and economic damage it becomes a natural disaster. e.g when a vulnerable population can’t cope using its own resources

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9
Q

define vulnerability

A

people’s ability to cope with hazard events . the greater the hazard and more vulnerable the people the greater the disaster

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10
Q

what were the impacts of the nepalese earthquake on the 25th of april 2015

A
  • Nepal is mountainous . The shaking caused landslides making rescue and aid efforts difficult in rural areas - Over 100 after shocks followed the initial earthquake causing more destruction and deaths making recuse work dangerous -many buildings collapsed in the capital kathmandu because they weren’t built to withstand earthquakes -The country’s infrastructure eg roads and water supplies were severely damaged - tourism fell after the earthquake putting people out of work -nepal’s emergency services were unable to cope and relied on over seas countries and aid agencies
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11
Q

how many layers does the earth have

A

three

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12
Q

what are the three layers of the earth

A

core mantle crust

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13
Q

what is the core of the earth

A

the most inner part (inner and outer core) inner core - solid centre made of mostly iron hottest part about 6000° outer core -semi molten mostly liquid iron and nickel temp of 4500°-6000°

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14
Q

what is the mantle

A

the widest layer of the earth surrounding the core . upper mantle is solid , below it the rock is semi molten forming the asthenosphere

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15
Q

what is the crust

A

the outer shell of the earths layers two types are oceanic and continental oceanic - thin - dense - 6-10Km thick-forming ocean floors continental -thicker - less dense - 45-59km thick - make up land masses

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16
Q

what are the 4 processes that drive plate movement / tectonic movement

A

mantle convection sea floor spreading subduction slab pull

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17
Q

what makes up the lithosphere

A

The crust and upper mantle make up the lithosphere

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18
Q

explain how mantle convection /convection currents cause plate movement

A

Originally thought this was the main theory however it’s much less accepted now: Heat produced by radioactive decay in the core heats the lower mantle creating convection currents within the asthenosphere,causing plate movement.

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19
Q

explain how sea floor spreading causes plate movement

A

Huge mind ocean ridges form when magma is forced from the asthenosphere and hardens forming new oceanic crust . This sea floor spreading pushes tectonic plates apart

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20
Q

evidence for sea floor spreading

A

the age of the sea floor gets progressively older with the distance from the mid ocean ridge PALEOMAGMISTISM - a record of changes in the earths magnetic fields . When lava solidifies and forms new rock the iron in it reflects the earths magnetic core and lines up with the earths magnetic direction. Mid ocean ridges show the patterns of magnetic direction mirrored on each side of the ridges

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21
Q

Explain how subduction causes plate movement

A

as two plates move towards eachother , one slides into the mantle into the subduction zone

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22
Q

what are plate boundaries

A

plate boundaries form where two tectonic plates meet

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23
Q

explain how slab pull causes plate movement

A

slab pull is increasingly seen as driving plate movement . newly formed oceanic material at mid ocean ridges becomes denser and thicker as it cools . causing it to sink into the mantle , pulling the plate down.

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24
Q

what are the three plate boundary types

A

divergent convergent conservative/transform

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25
what are divergent plate boundaries
-constructive plates MOVE APART
26
why do plates move apart in divergent - constructive plate boundaries
SLAB PULL SEA FLOOR SPREADING
27
what is the type of magma at divergent - constructive plate boundaries
BASALTIC LOW viscosity LOW silica / gas content runny less viscous lava forms SHIELD flat volcanoes
28
do earthquakes occur at divergent - constructive plate boundaries
they can occur but are quite small this is because there is no friction or pressure building up over time as they are moving apart not towards eachother
29
what are convergent - destructive plate boundaries
where two plates COLLIDE
30
what causes plate movement in convergent - destructive plate boundaries
SLAB PULL - forces subduction of oceanic plate because it is denser , under the continental plate as the plate is pulled by slab pull into subduction zone . pressure and friction from the plate movement and heat from the mantle start to melt the oceanic plate forming magma.
31
what type of lava is at a convergent destructive plate boundary
ANDESITIC HIGH viscosity HIGH silica content
32
what are explosions like at divergent constructive boundaries
Lower explosivity however may be of a longer duration
33
what are the explosions like at convergent - destructive plate boundaries
LESS frequent HIGH explosivity
34
do earthquakes occur at convergent - destructive plate boundaries
YES , often measure higher on the maginitude scale - ofetn seen with larger occurrences of Tsunamis
35
what happens at convergent - collision boundaries
plates move towards eachother but are being pushed up rather then subducted (both continental)
36
What is the magma like at Convergent-collision boundaries
there is very little magma because plates are being pushed up not subducted . VERY SMALL CHANCE OF VOLCANIC ERUPTIONS
37
do earthquakes occur at convergent collision boundaries
yes they are VERY LARGE VERY POWERFUL HARD TO PREDICT e.g nepal
38
what happens at a conservative /transform plate boundary
PLATES MOVE ALONGSIDE EACHOTHER AT DIFFERENT SPEEDS
39
what happens as the plates move alongside eachother at conservative boundaries
they create fault lines e.g sam andreas
40
do earthquakes occur at conservative/transform boundaries
yes , they are often very large
41
how do volcanoes form at volcanic hotspots
mantle plumes underneath the crust forming large magma chambers . as plates move over them we can get chains of volcanic islands e.g hawaii
42
why do introplate volcanoes form
could be because old fault lines which have moved because they are no longer on plate boundaries
43
what is Wegners theory (1912)
CONTINTENTAL DRIFT the theory that all continents used to line up perfectly creating pangea - there is matching fossil evidence -glacial evidence GSI (satellite mapping) and sea floor mapping all back up the idea of continental drift.
44
what are the types of waves
P waves s waves L waves
45
what are P waves
primary or pressure waves - move fastest -reach surface first -travel through solids and liquids -shaking backwards and forwards - least damaging
46
what are S waves
secondary or shear waves -move slower -travelling only through solids -moving sideways motion , shaking at right angles to the direction of travel -more damaging then P waves
47
What are L waves
surface love waves -move slowest and are last to arrive -The MOST damaging -shaking the ground from side to side - they are larger - focusing all their energy on the earths surface
48
what waves can be noticed earlier and can give a few minutes warning
P and S waves could be noticed much earlier on - can give a few minutes warning before loves waves
49
primary hazards of earthquakes
Ground shaking
50
secondary hazards of earthquakes
-tsunamis -landslides/avalanches -fires - could damage nuclear power points -liquefaction -crustal fracturing
51
what are the primary hazards of volcanoes
-gas eruptions -pyroclastic flows -tephra and ash fall -lava flows
52
what are the secondary hazards of volcanoes
-lahars (mud flows) -jokulhlaups
53
why do eruptions occur
pressure and tension builds up , pressure causes magma to rise up through the magma chamber and through the main vent. gas levels changing
54
why do mudflows occur
when a volcano erupts during terential rain
55
what three things cause Tsunamis
earthquakes usually submarine landslides volcanic eruptions - the energy released causes large water column displacement - as water is forced upwards it begins to travel upwards -gravity drags it back down forcing it to travel horizontally outwards towards shore - leading to waves which have a great wavelength often of several hundred miles - low amplitude - travel at a rapid speed of up to 500Km/h - ONLY become a problem when waves begins to show in shallow water- as the wave slows down the back catches up - increasing height (amplitude) - this is how it’s possible for the wave to travel so far in land
56
what can help predict tsunamis
time travel maps
57
risk disaster formula
risk disaster = hazard x vulnerability/ capacity
58
what are the three hazards
tsunami volcano earthquake
59
what effects vulnerability
-location - proximity , coastal , mountain etc -poverty -education and training -population density -ageing population ? young or old
60
what affects capacity to cope
-governance -level of development -planning and monitoring
61
hazard profiles
magnitude duration frequency spatial predictability areal extent speed of onset
62
how to measure earthquake
magnitude scale measures energy
63
how to measure volcanic explosivity
VEI index measures eruption
64
human factors that can affect how bad a hazard is
access to : -housing -education -health care -income
65
governance factors that can affect how bad a hazard is
-planning - law enforcement codes (building regulations) -protection programmes -response
66
geographical factors that affect how bad a hazard is
-population density -isolation /accessibility -urbanisation - age and speed
67
what is the tsunami case study
INDIAN OCEAN TSUNAMI BOXING DAY 26Th december 2004
68
what was the magnitude of the boxing day tsunami 2004
9.0-9.3 on the magnitude scale caused one of the worlds worse disasters
69
what was the proximity like of the epicentre of the tsunami
the proximity to the epicentre to densely populated areas was significant. a the earliest waves struck indonesia at 17 metres high
70
what are the coastlines like at neighbouring countries of indonesia
they are low lying and this allowed thr tsunami to travel inland
71
was there a warning system for the boxing day tsunami 2004
no
72
how many people were affected by the boxing day tsunami 2004
5 million people in 14 different countries
73
how many people died in the boxing day tsunami 2004
230,000 people died including 9000 tourists. 1.7 million left homeless
74
how much money did the tourist industry lose due to the boxing day tsunami
$25 million per month
75
how much was the cost of damage for the boxing day tsunami 2004
$10 billion
76
what happened to buildings in the boxing day tsunami 2004
coastal settlements were devastated , 70% of people were killed . 1500 villages were destroyed in sumatra
77

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