Hazards Flashcards
(137 cards)
1
Q
Event
A
People unaffected
2
Q
Hazard
A
People potentially affected
3
Q
Disaster
A
People affected
4
Q
What influences hazard impact
A
Development, hazard intensity, distribution, magnitude, incidence
5
Q
Geophysical hazards
A
Caused by land processes
6
Q
Atmospheric hazards
A
Extreme weather events originating in the atmosphere e.g. tropical storms, heatwaves, wildfires
7
Q
Hydrological hazards
A
Water-related e.g. floods, landslides, droughts
8
Q
El Nino Southern Oscillation
A
Fluctuates between El Nino (opposite to normal conditions, winds reverse, warm water and low air pressure towards S America increasing rain, high Australian pressure causes drought), neutral, and La Nina (exaggerates normal) every 3-7y. Recently exceptional El Nino events
9
Q
Hurricanes damage
A
Strength does not lead to damage as cell size, unreliable forecasting, rain, movement speed and sequencing
10
Q
Earthquakes damage
A
Most frequent hazard but massive differences in effects, frequency not increasing but human vulnerability is
11
Q
Volcanoes damage
A
Much less significant impact and loss of life than other hazards, affect 95000/yr
12
Q
Tsunami damage
A
Impact limited geographically as at the edges of some oceans but 2004 sent waves round world due to Indian Ocean bathymetry and 9.2 earthquake size, 5m waves in India 1700km from epicentre
13
Q
Multiple hazard zones
A
High human concentration (coastal and in NEEs), near plate boundaries, high concentration between tropics
14
Q
What are the responses to hazards
A
Fatalism, prediction, adaptation, mitigation, management, risk sharing
15
Q
Physical factors affecting response
A
Severity, accessibility, hazard type, time, weather, fauna and flora, frequency
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Q
Human factors affecting response
A
Politics, population density, money, accessibility, knowledge, development
17
Q
Who controls response
A
Government, academics, insurers, planners, relief agencies, emergency services, communities
18
Q
Hazard cycle
A
Hazard, emergency, recovery, reconstruction, disaster free period
19
Q
Limited response success example
A
Kashmir Earthquake 2005, Pakistan refused aid from India as at war over area and army slow, US criticised as didn’t raise enough, 80000 deaths as poorly built schools and hospitals. Challenges as war zone, Winter, mountainous
20
Q
Response success example
A
Boscastle flood 2004, no casualties as fast response close to RAF station
21
Q
Matrix risk
A
Likely impact and probability determine whether red, amber or yellow warning
22
Q
Hazard management cycle
A
Preparation phase, response phase, recovery phase, mitigation phase. Implemented preparation in Cockermouth after 2009 flood
23
Q
Effect of community preparedness and education
A
Disaster reduction most effective at community level as meets specific local needs, cheaper than emergency relief
24
Q
Technology in risk preparation
A
Remote sensing, GIS in plans and hazard maps for reduction, communication, Pacific ocean has well maintained tsunami warning systems, Indian ocean has none as LICs and NEEs but after 2004 USA and Japan installed some
25
Park response model
1: modify cause and event. 2: hazard event. 3: search, rescue and care. 4: relief and rehabilitation. 5: recovery (improvement)
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Compositional layers
Different chemical structure
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Mechanical layers
Act physically differently
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Crust
Thin outer layer (5-70km). Continental known as sial, thicker, less dense, granitic. Oceanic known as sima, thinner, denser, balsatic
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Mantle
Rich in iron and magnesium, mainly peridotite, 2900km
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Core
Made of iron and nickel, 3450km
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Lithosphere
Solid, divided into 7 large and many small tectonic plates, upper mantle and crust
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Asthenosphere
Rocks become plastic as solid from pressure despite temp so flow, peridotite
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Outer core
Semi liquid, mainly iron, spins with Earth's rotation to form magnetic field
34
Inner core
Solid, iron and nickel, radioactive decay supplies heat, convection currents
35
Convection currents
Unlikely to move plates as not large enough and 2/3 surface moves faster than mantle
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Ridge push (gravitational sliding)
Mantle material pushed into a plate gap, forcing them apart and up, gravity pushes down, allows sea floor spreading
37
Slab pull
Drives convection currents. Newly formed oceanic lithosphere at mid ocean ridges less dense than asthenosphere but denser with age so subducted on collision with continental plate
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Constructive/divergent boundary
Mid Atlantic Ridge between Eurasian and North American plates. Gravitational sliding, earthquakes and volcanoes
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Triple Junction: continental rifting
East African rift valley due to S extension of Arabian and African plate divergence and rifting from mantle plume: African plate will split to Nubian and Somalian. Continental filled with oceanic, earthquakes, and volcanoes
40
Oceanic-continental convergence
Andes due to collision of S American and Nazca plate. Mountains (obduction forms an accretionary wedge), volcanoes (andesitic magma from subduction liberating seawater locked in crust), earthquakes (Benioff zone), Atacama trench
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Continental-continental convergence
Himalayas due to collision of Indian and Eurasian plates and subduction of Tethys ocean floor plate dragging Indian. Himalayas from accretionary wedge, Tibetan Plateau, volcanic intrusion, earthquakes, crust 2x average thickness at 75km
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Oceanic-oceanic convergent
Subduction of the denser Pacific Plate under the Philippine Plate, where it creates the Marianas Trench and Aleutian Islands
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Conservative
San Andreas fault between N American and Pacific plates, 1300km long, right lateral strike slip fault as Pacific moving NW faster, shallow focus earthquakes
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Trench example
Atacama, S American and Nazca plates
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Volcanic arc example
Andes, Nazca and S American plates
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Island arc example
Aleutian islands, Pacific and Philippines plates
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Fold mountains example
Himalayas, Indian and Eurasian plates
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Rift valley example
East African rift valley, African plate
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Mid ocean ridge example
Mid Atlantic Ridge, N American and Eurasian plates
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Mantle plumes
Hot molten rock plumes from the mantle-core boundary to the Moho e.g. Hawaii
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Icelandic volcano
Molten balsatic lava effusions flow from long parallel fissures
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Icelandic volcano example
Skaftareldar, Iceland
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Hawaiian volcano
Fluid lava flows from a volcano's summit and radial fissures
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Hawaiian volcano example
Mauna Kea, Hawaii
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Strombolian volcano
Moderate bursts of expanding gases eject lava clots in nearly continuous small eruptions
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Strombolian volcano example
Stromboli volcano, Italy
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Vulcanian volcano
Moderate gas explosion laden with volcanic ash to form clouds
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Vulcanian volcano example
Gran Cratere, Italy
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Pelean volcano
Explosive outbursts generate dangerous pyroclastic flows
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Pelean volcano example
Mount Pelee, Caribbean
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Plinian volcano
Very violent as gases boil out of magma, caving it out to form ash clouds causing static electricity lightning
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Plinian volcano example
Mount Vesuvius, Italy
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Phreatic eruptions
Steam driven eruptions from when water is heated by volcanic activity, very dangerous and hard to predict
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Phreatic eruption example
Mt Unzen, Japan, 1991
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Volcano spatial distribution
Constructive, hotspots (silica poor red eruptions) and destructive (silica rich seabed grey)
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Volcano magnitude: Volcanic Explosivity Index
A 1-8 scale describing explosivity, technically not top but 8 supervolcano, based on volume material ejected
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Volcano frequency
50-60/month
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Volcano regularity
Type at each boundary regular
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Volcano predictability
Long-term with regularity and short-term with warning signs
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Lava flows
High viscosity slow e.g. 2002 Mt Nyiragongo exploded a petrol station, low viscosity follow terrain e.g. 1973 Heinaey Iceland threatened harbour so sprayed saltwater to divert
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Volcanic bombs (tephra)
Lava fountains have drops of lava that solidify
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Volcanic ash (tephra)
From explosions blasting apart rocks, creates sludge, very sharp so respiratory issues, collapse buildings as heavy, block Sun, Volcanic Winter
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Pyroclastic flow (nuee ardente)
6-700 degrees gas and tephra travelling over 200mph as heat ground so remove friction e.g. 3km after Merapi
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Volcanic gas clouds
Landslides release CO2 from bottom of lakes in volcanic vents e.g. 1986, Lake Nyos suffocated everyone in valley village
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Lahars
Volcanic mudflow from eruptions melting snow and mixing with ash e.g. 1985 Nevado del Ruiz, Colombia, eruption caused a huge rainstorm so lahar into Armero town, killed 23000/29000
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Jokulhlaup
Glacial outburst flood from eruption melting bottom of glacier, massive e.g. Eyjafjallajokull, 2010, peak flow 2-3000 m3/s
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Supervolcano caldera formation
Vents around edges cause caldera collapse e.g. Lake Taupo, New Zealand
78
Earthquake
A sudden, violent ground shaking of the ground caused by sudden energy release in the Earth's lithosphere that creates seismic waves
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Why do earthquakes occur
Lithosphere rigid and brittle so can fracture
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Earthquake spatial distribution
2 major belts: circumpacific and alpide, along all boundaries and hotspots e.g. Solomon islands
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Earthquake frequency
Occur every day at boundaries
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Earthquake regularity
No pattern and random so irregular
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Earthquake predictability
Nearly impossible, some microquake indication, can't predict magnitude
84
Shockwaves
Energy released from the sudden jolt that vibrates through the ground
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Tsunamis
Water displaced from underwater plate movement
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Liquefaction
Soil saturated and vibrations weaken it so subside when a large weight on it
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Landslides and avalanches
Displace large volumes material
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Focus
Point energy released from
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Epicentre
Point on surface directly above focus
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Body waves
Primary and secondary waves
91
Primary
Compressional
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Secondary
Transverse waves do more damage as lateral movement
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How body waves inform Earth's structure
P waves travel through liquid and solid but different travel speeds and refraction, S wave shadow as can't travel through liquid core
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Surface waves
Rayleigh (up and down) and Love (side to side) waves after body
95
How are earthquakes measured
Seismometers, use vibrations if old fashioned and electromagnets if modern
96
Triangulation
Locates an earthquake using 3 stations as we know how fast P+S waves travel (P faster) so time between indicates distance but not direction so must triangulate
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Moment Magnitude Scale
Logarithmic, measures energy release, 1 increase x32 energy
98
Modified Mercalli Scale
Qualitative, measures intensity, subjective, accounts for focus depths, measured with visible aspects, I to XII
99
Earthquake proofing
Building shape, automatic shutters and shut off, secure heavy objects, open areas for safe evacuations, good road access, earthquake safety training, cross bracing, sheer walls (steel bars), Taipei 101 66 tonne mass dampener
100
Wildfire
A large uncontrolled destructive fire that burns quickly over woodland/grassland
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Ground fire
Ground burns slowly with no flame and little smoke
102
Surface fire
Leaf litter and low lying plants burn faster as more O2 available
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Crown fire
Moves rapidly and intensely through canopy
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Conditions needed for wildfires
Vegetation type, fuel characteristics, climate, fire behaviour (creeping or running)
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Wildfire impacts
Some plants need fire to germinate, affects forest management, fire removes soil OM
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Responses to wildfires
Spray water on house roofs to prevent burning, train civilians as auxiliary firefighters, controlled burning of firebreaks, lightning detection systems, land use planning ensures houses 30m from forest and in low density clusters
107
Megafires
Fires over 1000 acres, predicted to be 50% more by 2100
108
What % of new USA homes in flammable areas
60%
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How to protect from wildfires naturally
Natural patchwork forests of older trees
110
LA fires damage
Mostly in Eastern Palisades, some fire resistant houses survived
111
LA fires causes
Santa Ana winds, Hollywood hill camper barbecues, prosecuted an electrics company for sparks
112
Amazon fires
2019, unusual as often too moist
113
Hurricanes
Atlantic, almost none in S
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Typhoons
W Pacific, highest frequency
115
Cyclones
Indian Ocean and Australia
116
Where and when do tropical storms occur
Coasts, travel in trade wind direction, occur late Summer to Autumn, 5-30 latitudes but higher off N America
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Where don't tropical storms occur
Not in SE Pacific, S Atlantic, and equator
118
Tropical storm magnitude
1-5 Saffir Simpson Scale off windspeed
119
Tropical storm frequency
N hemisphere: Jun-Nov, S hemisphere: Nov-Apr, 2x 4-5 in 30y
120
Tropical storm regularity
Irregular as same areas but not route as depends on storm and climactic conditions
121
Tropical storm predictability
Of general route as satellite tracking of cloud formation and movement
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What windspeeds
>120 km/hr winds
123
What diameter
600km
124
What pressure
950 to 870mb
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Formation conditions
Ocean water >27C (latent heat release), late Summer allows time to heat through, unstable atmosphere
126
Tropical disturbance
Associated with an easterly wave in the upper wind
127
Tropical depression
At least one closed isobar (band of atmospheric pressure)
128
Tropical storms
Sustained winds >37mph
129
Hurricane/ typhoon/ cyclone
Sustained winds >120 km/h
130
Hurricane formation
Warm air rises rapidly in low pressure conditions after evaporation, causing low pressure, self-propagating system, Coriolis effect causes air to spin around an eye, adiabatic cooling after air rises forms bands of cumulonimbus cloud, heat given off allows more evaporation
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Frequency and strength correlation
If stronger, less frequent
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Tropical storm trends in America
August: further out in Atlantic forming. September: widest area covered, forming in Gulf of Mexico. October: less area but further inland
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Hazards
Wind, heavy rain, landslides, tornadoes, floods, storm surge (low pressure domes ocean surface)
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What is needed to be a MHZ
Tectonic hazards, climactic hazards, vulnerable population
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How are MHZs identified
2010 WB and Colombia project to allow planning (not if different priorities)
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Where is the highest economic and mortality risk MHZ
Taiwan
137
What is the only HIC in the top ten most economically and mortality affected MHZs
Japan
