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geography alevel- edexcel > TECTONICS > Flashcards

TECTONICS Flashcards

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1
Q

what is a natural hazard

A

naturally occurring event with the potential to cause loss of life/property.

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2
Q

what is a natural disaster

A

when the natural hazard causes social, economic and environmental damage.

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3
Q

vulnerability

A

people’s ability to cope with hazard events

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4
Q

what does vulnerability depend on

A

how exposed to the hazard the population is. how susceptible to human and/or economic loss because of where they live

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5
Q

case study Nepalese earthquake

A
  • date= 25 April 2015
  • magnitude=7.8
  • half its population living in poverty
  • infrastructure severely damaged(not built to withstand natural disaster)
  • is mountainous= many landslides=rescue is difficult
  • emergency services unable to cope
  • tourism fell=unemployment
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6
Q

deggs disaster model

A

overlap of hazard and vulnerability causing disaster

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7
Q

constructive/divergent plate boundaries

A

plates moves apart forming new crust

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8
Q

mid ocean ridges

A

an elevated region with a central valley on an ocean floor at the boundary between two diverging tectonic plates where new crust forms from upwelling magma.

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9
Q

rift valleys

A

A rift valley is a lowland region that forms where Earth’s tectonic plates move apart, or rift. Rift valleys are found both on land and at the bottom of the ocean, where they are created by the process of seafloor spreading. where the land between two continental/oceanic plates collapses.

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10
Q

destructive/convergent plate boundaries

A

plates move towards each other where the lighter /less dense plate subducts

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11
Q

subduction

A

the movement of the less dense plate sliding under the denser plate
oceanic plates are usually more denser than continental plates

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12
Q

oceanic plate-continental plate

A

oceanic plate subducts creating fold mountains, where plate collision forms folding.
constant movement=continuous folding=increase friction in Benioff zone. magma pushes through gapes creating explosive volcanic eruptions

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13
Q

oceanic plate-oceanic plate

A

lighter plate subducts, deep ocean trenches and volcanoes form. submarine volcanoes grow to form island volcanoes(island arcs).
shallow deep focus earthquakes occur

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14
Q

Benioff zone

A

area where friction is created between colliding tectonic plates , resulting in intermediate and deep earthquakes

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15
Q

continental-continental

A

collision margin occurs forcing rock upwards forming high mountains e.g Himalayas. =no volcanic activity and earthquakes are shallow focus

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16
Q

conservative boundaries

A

2 plates slide past each other.(move parallel towards each other in opposite directions.)form transform fault. no volcanic activity. friction creates powerful earthquakes . at points where plates get stuck to each other stress is built up. the longer the stress is built up the greater the magnitude of the earthquake.

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17
Q

Collison margin

A

If two continental plates collide, neither can sink and so the land buckles upwards to form fold mountains. This is called a collision margin.

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18
Q

How are earthquakes caused

A

formed along plate boundaries
friction between plates causes pressure to build up release of this stress/pressure causes earthquakes at different magnitudes

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19
Q

explain and name the 3 types of seismic waves

A
  • P WAVES(primary)= are the fastes waves, move through solid and liquid. moves forwards and backwards creating expansions and compressions. least damaging
  • S WAVES(secondary)= moves slower than p waves. moves through solids only. moves in a sideways motion at right angles to direction of travel. more damaging than p waves.
  • L WAVES(love)= moves slowest. last to arrive. Shake ground side to side . most damaging. are larger. and focus most of its energy onto earths surface.
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20
Q

what are seismic waves measured by

A

seismometer

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21
Q

primary impacts of earthquakes

A
  • crustal fracture
  • building / infrastructure collapse/damage
  • ground shaking
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22
Q

secondary impacts of earthquakes

A
  • liquefaction, surface of rocks acts more like a liquid than solid during movement, causing building + roads to sink +power and gas lines to break causes fires.
  • Landslides/avalanches,
  • tsunami-cause coastal flooding
23
Q

loma prieto earthquake -case study

A 
date-17 October 1989
magnitude- 6.9
location- san Francisco -Loma Prieto
built on soft sand- liquiefaction-buildings and roads collapsed
caused 42-67 earthquake related deaths
24
Q

aftershocks of eartyhquakes

A

larger earthquakes= more aftershocks
cause more damage to building structure= more possible death=more economic environmental damage.
Aftershocks are smaller earthquakes that occur in the same general area during the days to years following a larger event or “mainshock.”

25
Q

measuring earthquakes

A

magnitude- is energy release by epicentre. MMS measures energy released by earthquake. using information on- seismic waves, rock movement, fault surface broken by earthquake and resistance to rocks affected
scale= 1(small)-10
- intensity = impact of earthquake on people MMIS(modifies Mercalli intensity scale= I(hardly noticed) - XII(catastrophic)

26
Q

earthquake prediction

A

no accurate method, relies on forecasting and researching foreshocks, although not reliable.

27
Q

Causes of volcanic eruptions

A

as plates moves pressure builds up and hot magma rises above through crust. as lava cools rock forms- so volcanoes grow as they erupt.

28
Q

primary hazard of volcanoes

A
  • lava flows
  • pyroclastic flow- fast moving destructive mix of dense hot ash gas and rock from a volcano-v. dangerous
  • ash and tephra falls- ash blasted from eruptions, destructive , can injure or kill, travel thousands of km, case poor visibility and slippery roads.
  • gas eruptions-dissolved gasses released during an eruption-water vapour, CO2 and SO2, travel huge distances.
29
Q

Secondary hazard of volcanoes.

A
  • lahars-flows of mud, water and rock -form when heavy rainfall during eruptions erodes loose rock and soil or eruptions melt snow/ ice
  • jokulhlaups- when volcanic eruptions melt part of glaciers. the sudden release of gravel water and ice is v. dangerous.
30
Q

measuring volcanic eruptions

A

volcanic explosivity index- VEI
0(non-explosive)-8
based on volume of tephra, height of material ejected into atmosphere, duration, observations

31
Q

predicting volcanoes

A

using gps, seisometers and satallite bases radar. are not 100%accurate

32
Q

hotspots

A

A hot spot is an area on Earth over a mantle plume or an area under the rocky outer layer of Earth, called the crust, where magma is hotter than surrounding magma. The magma plume causes melting and thinning of the rocky crust and widespread volcanic activity

33
Q

impacts of tsunami

A

-damage to infrastructure
-travel for miles inland
-change landscape, more severely on small islands.
-drowning/injuries/death
secondary hazards-
famine
disease outbreak
homelessness
economic damage
damage to ecosystems

34
Q

predicting tsunami

A

little way of predicting,

seismic sensors used to detect undersea earthquakes as well as DART(deep ocean assessment and reporting of tsunami.

35
Q

causes of tsunami

A

earthquake underwater, causes the displaced of water in sea. the length of wave increases when closer to land. the size of earthquake and the proximity to land determines the length of wave
length of wave can range from 1 meter to 30 meters etc.

36
Q

Indian ocean tsunami- case study

A 
date- 26 december 2004
magnitude-9.0-9.3
indian ocean plate lifted 15 metres
proximety-17 metres
low lying coastland- cased the wave to travel very far inland
social:
5 million people affected
230 000 death as well as 9000 tourists
1.7 million left homeless
70% of people in villages dead
no early warning system
14 countries affected
environmental:
ecosystems such as mangroves and coral reef damaged
economic:
water supplies contaminated by salt water
total cost- $10 billion
37
Q

Iceland Eyjafjallajökull erupts- case study

A 
date- april 2010
location iceland
ash cliouds affected flights
100 000 flights cancelled
affected 10 million people
economy in kenya fell due to no exportations on green flowers
38
Q

hazard risk formula

A 
      capacity
39
Q

political factors affecting risk from natural hazards

A
  • building codes and regulations
  • quality of infrastructure
  • preparedness plans
  • efficiency of emergency services
  • quality of communication systems
  • public education and practice of hazard response
  • extent of government corruption
40
Q

economic and social factors affecting risk from natural hazards

A
  • level of wealth(peoples ability to protect themselves and recover from a hazard)
  • access to education
  • quality of housing
  • quality of healthcare
  • income opportunities
41
Q

physical and environmental factors affecting risk from natural hazards

A
  • density of population
  • speed of urbanisation
  • accessibility of an area
42
Q

haiti-developing country-case study

A

date-12 January 2010
magnitude 7.0
shallow focus
liquefaction causing building sink.
epicentre only 24km to capital Port-au-Prince
-is poor countrry, not enough resources for earthquake preperation
high levels government corruption therefore reduced living standards and poor infrastructure=lack of regulations
-rescue =difficult = g=high population density
-not many people knew what to do because of low preparedness for disaster.
roads destroyed so aid could not come in as fast.
destroyed building- recovery and relief difficult.
cholera outbreak lasted 6 years- 720 000 affected.

43
Q

Haitis recovery- case study continued

A

-many officials dead, NGO needed for emergency services,
-corruptions= other countries unwilling to give aid.
80 000 people in temporary housing
in 2015:
-new buildings, roads& schools built
-health statistics improved
-stronger government

44
Q

China -emerging country- case study

A

date 12 may 2008
magnitude-7.9
45.5 million people affected
5million homeless
many injuries, high economic cost
poor building regulations
fewer deaths since the earthquake was rural
is wealthier than Haiti-afford rescue missions
people at risk from landslides relocated
within only 2 weeks temp homes and roads where built.
99%of destroyed farmland rebuilt.

45
Q

japan-developed country- case study

A 
date- 11 march 2011
magnitude 9.0
fukishima nuclear power plant destroyed-47 000 people evacuated
had fewer deaths than Haiti and china
-strict building regulations
-low levels of corruption
-earthquake education with frequent practise drills in schools and businesses
- disaster plane:
-10 meter high tsunami walls
-evacuation shelters
-marked evacuation routes
-earthquake emergency kit.
-early warning system
response:
all radio and tv live broadcast 
110 000 defence troops immediately mobilised
received aid from 20 countries
only negative was the plant hadn't been built to withstand tsunami.
46
Q

hazard profiles

A

show characteristics of hazards and help show ways of different events may be compared

47
Q

multiple hazard zone

A

countries exposed to multiple hazards; need aid from other countries to plan disaster prevention

48
Q

Philippines; multiple hazard zone- case study

A

7107 islands
101 million people
25%pop lives in poverty
mostly mountainous with coastal lowlands
volcanoes- located in the ring of fire
tsunami- coasts face the pacific which is the most tsunami-prone area
typhoons- sits within the typhoon belt
deforestation makes landslides common
vulnerability:
economic development led to rapid urbanisation=high pop density
poor live in coasts and exposed to storm surges
2006 earthquake- killed 15, damaged 800 buildings and 3-meter tsunami

49
Q

describe the 4 stages in hazard management

A

1) mitigation; reduce loos of life and damage to infrastructure and environment- plan land use, building regulations and defenses
2) preparedness; minimize loss of life and property-early warning systems, organise evacuations, raise awareness
3) response; aim to save lives and protect property- rescue/search/evacuate, restore infrastructure, medical care
4) recovery; short-term; immediate needs- medidocal care, transport, food water, temp housing. long term;reduce vulnerability- rebuild homes schools and infrastructure.

50
Q

park hazard response curve

A

can be used to asses/cpompare how well places respond after a hazard event

51
Q

hazard mitigation strategies

A
  • land use zoning
  • diverting lava flows
  • GIS mapping
  • hazard resistant design and engineering defences such as sloped roofs on houses near volcanoes to reduce ash build up and collapse
52
Q

hazard adaptation startegies

A
  • high tech monitoring; GIS, mobile phone, early warning system, satellites
  • crisis mapping
  • modeling hazard impact
  • public education
53
Q

list 2 key players managing loss

A

-AID DONORS;
clean water , food, reconstructing buldings
-NGO
provoide funds, search and rescue assist in building schools and medical centers.

geography alevel- edexcel (6 decks)

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