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Physical Geography > TECTONICS! > Flashcards

TECTONICS! Flashcards

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1
Q

what are the three types of plate margins?

A

conservative
constructive
destructive

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2
Q

what are oceanic tectonic plates made of?

A

basaltic rock

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3
Q

destructive plate margins:

A 
the oceanic plate slides beneath continental
rocks catch against one another
pressure between plates build
plates slip past each other
ground shakes
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4
Q

what causes plates to move?

A

movement in the mantle

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5
Q

what thickness are oceanic and continental plates?

A

oceanic: 7-10km
continental: 25-75km

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6
Q

three types of tectonic hazard:

A

earthquake
tsunami
volcano

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7
Q

what is a cause of intra-plate earthquakes?

A

stresses reactivating ancient fault lines

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8
Q

formation of intra-plate volcanoes:

A

isolated plumes of concerting heat rise towards surface
plume remains stationery but tectonic plate above moves
plate movement continues to produce chain of volcanic islands

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9
Q

what is a hazard

A

a natural/geophysical event that has the potential to threaten both life and property

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10
Q

how are hotspots made?

A

hot mass of rising heat
a weakness in a plate
magma rises to the surface

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11
Q

what is the name given to the impact of the Indo-Australian plate with the Eurasian plate?

A

collision zone

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12
Q

the inner and outer core are made from…

A

iron and nickel

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13
Q

what process happens at collision margins?

A

fold mountains are formed

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14
Q

what is true of the earth’s structure?

A

the core is a source of radioactive heat
the lithosphere is 80-90km thick
outer core is more liquid than inner core

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15
Q

what proves new crust is created by sea floor spreading at mid-ocean ridges?

A

paleomagnetic signals

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16
Q

what can be expected at constructive plate margins?

A

basaltic eruptions
low viscosity lava
low magnitude, shallow-focus earthquakes

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17
Q

order of earth’s structure

A 
inner core
outer core
mantle
asthenosphere 
lithosphere
crust
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18
Q

what are some plate tectonic discoveries?

A

Wegener’s continental drift hypothesis
seafloor spreading creates new crust
slab pull drags down high density ocean floor at convergent boundaries
gravitational siding at divergent boundaries
internal radioactive hear drives convection currents

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19
Q

what happens at the Californian San Andreas fault?

A

transform margin: high magnitude, shallow focus earthquakes are common but no volcanic activity

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20
Q

what do higher altitudes of oceanic crust at ridges create at divergent plate boundaries?

A

gravitational sliding

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21
Q

how is energy released from the focus of an earthquake ?

A

seismic waves

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22
Q

what type of earthquake wave causes the least damage?

A

p-waves

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23
Q

what are the causes of deep-focus earthquakes?

A

previously subducted crust moving towards earth’s core
previously subducted crust heating up
previously subducted crust decomposing

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24
Q

what is the point directly above the centre of an earthquake on the earth’s surface?

A

epicentre

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25
when an earthquake happens, what waves have the ability to shake the ground violently, but what cause more damage?
s-waves | l-waves
26
what are shallow focus earthquakes?
where the focus is 0-70km under earth’s surface
27
types of earthquake wave:
l-waves: only across surface, cause most damage p-waves: fastest, cause least damage s-waves: shake ground violently, only produced by some earthquakes
28
why are deep focus earthquakes less damaging than shallow focus earthquakes?
shock waves have to travel further so cause less shaking at surface
29
what are the main secondary hazards of earthquakes?
liquefaction tsunamis landslides
30
two primary hazards of an earthquake:
ground shaking | crystal fracturing
31
what happened in Pompeii in AD79?
Mount Vesuvius erupted and covered the city with pyroclastic flow
32
what is a jökulhaup?
type of glacial flooding caused by melting ice caps and glaciers (secondary hazard of some volcanoes)
33
what is true of pyroclastic flow?
very hot and high velocity
34
what is a lahar?
fast mudflows that happen when rain mobilises deposits of volcanic ash
35
primary hazards of volcanoes:
ash falls pyroclastic flow lava flows volcanic gases eg. CO2, carbon monoxide
36
what follows the vertical displacement of the seabed?
water column displacement
37
characteristics of tsunamis:
``` often preceded by drawback reaches coast as wave-train very short amplitude at sea very long wavelength at sea high velocity (speeds of up to 700ph) ```
38
the Boxing Day tsunami:
epicentre in Banda Aceh magnitude of 9.2 happened in 2004
39
what is a drawback?
when water is sucked up and away causing a localised drop in sea level
40
which direction is the seabed displaced after a submarine earthquake?
vertically
41
what is the probability of a hazard happening and creating a loss of lives/ livelihood
risk
42
how is a populations ability to cope with a natural disaster increased?
emergency evacuation, rescue and relief systems
43
what is vulnerability?
the risk of exposure to hazards combined with an inability to cope with them
44
what does the PAR model say?
risk is a function of vulnerability and nature of tectonic hazard
45
what is a disaster?
when a hazard has a significant impact on people: the consequence of a hazard happening
46
what is the hazard risk equation?
risk = (hazard x vulnerability) / capacity to cope
47
what does the PAR model show?
the connections between the nature of a hazard and its wider context
48
what does the PAR model stand for?
pressure and release
49
why is it difficult to compare impacts between countries?
the hazard itself will be different socio-economic characters are different deaths in developed countries usually low, but high in developing countries
50
what are some social impacts of a hazard?
deaths, injuries, physical health impacts, psychological health impacts
51
measuring tectonic hazards:
volcanoes: VEI, magnitude earthquakes: MMS, mercalli scale
52
what was the areal extent of the Kashmir 2005 earthquake?
1000km2
53
what would be associated with high risk natural hazards?
``` low frequencies large areal extents rapid speeds of onset low spatial predictability high magnitudes ```
54
information contained in hazard profiles:
``` magnitude speed of onset areal effect duration frequency spatial predictability ```
55
hazard profile of Kashmir earthquake:
``` areal extent of <1000km2 MMS 7.6 aftershocks of MMS 6.4 damage centred on Muzaffarabad ground shaking lasted 30-45 secs ```
56
what magnitude and frequency would a high risk event have?
high magnitude and low frequency
57
what do hazard profiles summarise?
the physics processes shared by all hazards so that decision makers can determine which areas are most at risk
58
which of the following are characteristics of places with a low HDI (<0.55)?
low education levels people lack basic things in ‘normal’ time poor access to healthcare informal housing
59
why are death tolls from natural disasters higher in urban areas than rural?
high concentration of people at risk
60
what should governments be doing after a disaster?
meeting basic needs by proving sufficient food and water | tackling corruption and making sure aid money is not taken by officials
61
zoning
splitting up land use between different areas of a city to make sure there are no houses on unstable land
62
what does HDI stand for?
human development index
63
what counts as having a low HDI score?
less than 0.55
64
immediate response to the Tohoku earthquake and tsunami
search and rescue preventing nuclear disaster at Fukushima evacuating people from the Fukushima area
65
what kind of tectonic zone did the Tohoku earthquake and tsunami occur on?
subduction
66
statements about the 2011 Tohoku earthquake:
``` 16,000 known deaths economic losses were US$300bil magnitude MMS 9.0 tsunami travelled up to 20km inland happened on a subduction zone ```
67
what was he government post disaster report for the Tohoku earthquake and tsunami focused on?
future safety measures
68
features of the Gorkha earthquake:
MMS 7.9 90km NE of Kathmandu 9000 deaths 22000 injured
69
how much financial aid did the Asian Development Bank provide for reconstruction work?
US$200million
70
aid post-earthquake:
ADB gave US$200 million 1mil needed emergency food severe gender discrimination
71
statements about the 2015 Gorkha earthquake:
NE of kathmandu 2.8mil people displaced from kathmandu valley 9000 deaths, 22000 injured magnitude MMS 7.9
72
statement about the 2010 Mount Merapi eruption:
large pyroclastic flows caused damage eruption came from a composite cone a lahar caused devastation the volcano is at a subduction zone
73
things delivered by government aid post-eruption:
food water hygiene kits
74
what was the VEI of the 2010 Mount Merapi eruption?
4
75
Mount Merapi eruption:
``` VEI of 4 large clouds of ash 353 deaths 350000 successfully evacuated rice harvest lost forest destroyed by pyroclastic flows ```
76
Mount Merapi 2010 eruption responses:
pre-eruption: evacuated everyone within 20km of the volcano | post eruption: government aid (food, water, hygiene kits), local airports shut, refugee shelters
77
statements about earthquakes since 1980:
15-40 disasters per year large disasters have skewed death numbers economic losses have increased
78
what % of earthquake deaths since 2005 can be accounted for by Kashmir (2005) Sichuan (2008) and Nepal (2015)?
40%
79
characteristics of multiple hazard zones:
at risk from global climate perturbations eg. ENSO geologically young eg. prone to landslides on major storm tracks eg. mid-latitudes or on tropical cyclone tracks tectonically active eg. earthquakes and volcanoes are common
80
what does ENSO stand for?
the El Niño Southern Oscillation
81
examples of large tectonic disasters in the himalayas:
Kashmir 2005 Sichuan 2008 Nepal 2015
82
how many volcanic eruptions have killed more than 100 people since 1980?
7
83
what would you use to record volcanoes ‘bulging’ as magma rises?
tilt meter
84
equipment to monitor volcanoes:
gas spectrometer: analyse gas emissions that can point to increased eruption likelihood seismometer: records minor earthquakes that indicate magma movement tiltmeter: record volcanoes bulging as magma rises
85
what does forecasting mean?
giving a percentage chance of a hazard happening
86
what does prediction mean?
knowing when and where a natural hazard will strike so that meaningful action can be taken
87
the hazard management cycle stages:
response (immediate rescue help) recovery (rebuilding infrastructure and services mitigation (trying to reduce scale of next disaster) preparedness (community education and resilience building)
88
what does the Park Disaster Response Model show?
the different stages of disasters impact of disaster on quality of life usefulness of management strategies response curve (depends on preparedness and economic development)
89
how can land use zonin be used?
to prevent building on low lying coasts to avoid tsunami damage avoid building on areas where liquefaction is likely
90
what would be used in an earthquake-proof building?
cross-bracing
91
what are examples of emergency aid?
search and rescue | emergency food water and shelter
92
how can vulnerability to natural disasters be modified?
using hi tech monitoring to monitor volcanoes and predict eruptions through community preparedness and education
93
why would you build a building with deep foundations, cross-bracing and counterweights?
to resist earthquake damage

Physical Geography (7 decks)

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