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Hazards Flashcards

(103 cards)

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1
Q

Hazards can be categorised into

A

Magnitude
Frequency
Duration
Spatial concentrations
Speed of onset

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2
Q

Risk

A

The probability of a hazard occurring and creating loss
The exposure of people to a hazardous event presenting a potential threat to themselves, their possessions and the built environment in which they live

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3
Q

Vulnerability

A

Risk and ability to cope
HICs may be less vulnerable as they have more money to recover

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4
Q

Hazard

A

A threat which ahs the potential to cause injury, loss of life, damage to property, socio-economic disruption or environmental degradation. Can be caused by either natural or human processes

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5
Q

Natural hazards

A

Hazards which occur in the physical environments of the atmosphere, lithosphere, and the hydrosphere

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6
Q

Disaster

A

Hazardous event that causes unacceptably large numbers of fatalities and/or overwhelming property damage. Occur as a result of a hazard
UN classifies a hazard a disaster when:
>10 people killed
>100 people affected
State of emergency is declared
Request by government for international assistance

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7
Q

Categories of natural hazards

A

Geophysical - caused by movements of the earth
Atmospheric - weather related
Hydrological - water-related hazards

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8
Q

Factors that influence your perception of a hazard

A

Previously affected by a disaster - may be more wary next time it happens - takes more precautions
Never affected by a disaster - may be naive to how much the hazard will affect them or perhaps be overly worried
Primary sector worker - industry may be more likely to be affected - crops dying, injuries preventing physical labour, rural land rendered inaccessible
Tertiary sector worker - may be less affected as a lot of money will be focussed on rebuilding the tertiary sector. If can’t go to work likely to still be paid
Highly educated - more likely to know the affects of the disaster
Poorly educated, suspicious of the media - less likely to know how the disaster will impact them, won’t believe new coverage of the event

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9
Q

Integrated risk management

A

Often used when incorporated identification of the hazard, analysis of the risks, establishing priorities, treating the risk and implementing a risk reduction plan

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10
Q

Prediction

A

Key is to improve monitoring which means warning can be issued
+
Grindavik - predicted volcano and everyone was evacuated
-
Haiyan - didn’t correctly predict route

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11
Q

Protection

A

Aim is to protect people, their possessions and the built environment. Usually involves modifications to the built environment
+
Storm surge sea walls in East USA
-
Fukushima nuclear power station - tsunami wall failed

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12
Q

Prevention

A

For natural hazards it is probably unrealistic although there have been ideas such as cloud seeding in potential tropical storms
+
Otley flood prevention
-
Carlisle flood defence didn’t work

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13
Q

Risk sharing

A

a community preparedness strategy where the risk of a natural hazard is shared among members, and they collectively invest in mitigation measures to reduce future impacts. This involves pooling resources
+
Emergency shelters in hurricanes
-
Hurricane Katrina

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14
Q

How can we track tropical storms

A

Computer tracking programmes - forecast paths
Satellite + radar systems - maintain watch on progress
Tracking stations in hurricane hotspots - Miami + Japan

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15
Q

How predictable are tropical storms

A

Clearly seen, can be tracked by satellite
The specific requirements mean that scientists know when and where they will form
HOWEVER
Each hurricane is unique both in its own structure and dynamics and its meteorological
Small changes in the early development of tropical storms can have massive impacts later on

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16
Q

Storm surges

A

Pose the greatest threat to life from all hazards created by tropical storms
high winds pushing the seawater towards the coast, causing it to pile up there. There is also a smaller contribution from the low pressure at the centre of the storm “pulling” the water level up
Storm surge can reach heights of 20ft and can span hundreds of miles of coastline
Can result in loss of life, buildings destroyed, beach + dune erosion, and road and bridge damage

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17
Q

Heavy rainfall from tropical storms

A

Tropical storms often produce widespread torrential rains in excess of 6 inches
May result in destructive floods - major threat for people living inland
Rainfall amounts related to speed and size of the storm

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18
Q

High winds in tropical storms

A

Tropical storm-force winds are strong enough to be dangerous if caught in them
Hurricane-force winds, 74-150+ mph winds can destroy homes and buildings
Wind force measured by Saffir-Simpson scale

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19
Q

Landslides from tropical storms

A

Increased flooding may cause landslides in mountainous regions
Can cause the destruction of crops, roads, bridges and villages. Most areas along US coastline prone to hurricanes are not very mountainous. The most susceptible places are central American and NW Pacific
e.g. intense rain from Hurricane Mitch (>4in/hour) caused a massive landslide on a volcano in Honduras

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20
Q

Ground fire

A

Burns beneath the ground in layers of organic peat

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21
Q

Surface fire

A

Burns across surface vegetation

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22
Q

Crown fire

A

Spreads across tree canopies + affects forested areas
BAD

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23
Q

Ladder effect in wildfires

A

Describes the process of fires spreading from the forest floor to the canopy

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24
Q

Distribution of wildfires

A

Hot places

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25
Benefits of wildfires
Small regular areas burning can reduce amounts of fuel, lowering the likelihood of large fires Remove alien plants Ashes add nutrients (previously locked in other vegetation) to the soil Controlling insects by killing off older or diseased trees
26
Human causes of wildfire
Cigarettes Campfires + barbecues Fireworks Arson (biggest cause)
27
Physical causes of wildfire
Lightning - biggest cause Volcanic eruptions Spontaneous heating - occurs when high dry material and no flow of cooling air El Nino Drought
28
Primary effects of wildfire
Smoke Destruction of property + possessions Loss of life + injury Loss of vegetation + crops Loss of animal habitats
29
Secondary effects of wildfire
Increased soil erosion as vegetation is no longer there the bind the soil Loss of jobs + income for agricultural workers who lose crops Homelessness Insurance premiums rise Access to recreational areas is restricted Health problems from inhalation of smoke
30
Disaster relief cycle in wildfire
Preparation (making buildings and residents ready) → Mitigation (reducing the potential severity of impact) → Response (dealing with immediate threat) → Reflection → Recovery (healing and regaining control) → Adaptation (making change to meet needs)
31
Response to wildfires
Fire lines - a break is made in the vegetation to try and prevent the wildfire from spreading Firefighters spray the fire with water and foam Spray ahead of wildfires to prevent spreading Back burning areas ahead of the fire are sprayed to reduce fuel Air drops - fire retardant dropped on fire
32
Preparation for wildfire for homes
Have a fire hose No dense trees near the house Mowing vegetation 100ft away from house Burnable materials (e.g. woodpile) kept away from the house Avoid outdoor burning
33
El Nino
Happens when weakening trade winds allow the warmer water from the western Pacific to flow toward the east. The clouds and rainstorms associated with warm ocean waters also shift toward the east, leaving drier conditions in Australia. Tropical thunderstorms are fuelled by hot, humid air over the oceans. The hotter the air, the stronger and bigger the thunderstorms. As the Pacific's warmest water spreads eastward, the biggest thunderstorms move with it. This increases the intensity and frequency of tropical storms forming over the Pacific.
34
What makes people vulnerable to wildfires
Geographical positioning - El Nino, Indian Ocean Dipole, high pressure ↑ urban sprawl and population means more people living near forests etc Drought Downwind from dry winds Areas inland with lots of vegetation/type of vegetation ↑ rural populations
35
Crust
Continental (30-50km)/oceanic crust (5-10km)
36
Heat from the core
>5000 C Primordial heat left from Earth's formation is trapped Radiogenic heat produced by radioactive decay
37
Biological evidence for plate tectonics
Fossils found in areas that weren't near each other so concluded that they used to be - Pangaea - and that's why fossil evidence can be found on different continents Fossil brachiopods found in India are comparable with ones in Australia Fossilised remains of a plant which existed when coal was being formed have been located only in India and Antarctica
38
Geological evidence for plate tectonics
South America fits with Africa Evidence of a late-Carboniferous glaciation deposits found in SA, Antarctica and India, the formation of these cannot be explained by their current position Rock sequences in northern Scotland closely match formations in eastern Canada and Appalachia Sea-floor spread - stripes of metals are magnetised according to polarity of earth which flips every 400k years. Evidence of sea floor spread as the magnetic bands are mirrored either side of the mid-Atlantic ridge
39
Characteristics of young fold mountains
High peaks (>6km), steep slopes, deep valleys Glaciers River sources due to snow melt No volcanoes at destructive but yes at collision e.g. Himalayas
40
Collision plate boundary
Convergence of two continental plates
41
Destructive plate boundary
Convergence of a continental and oceanic plate
42
Formation of young fold mountains
Two tectonic plates moving towards each other at a destructive plate boundary and there is slab pull. Sediments between the plates are compressed into rock and folded into mountains
43
Characteristics of rift valleys
Long + narrow with steep sides Floor is flat or gently sloping Thick layers of sediment from erosion Volcanoes Great Rift Valley - Africa, Mt. Nyiragongo
44
Formation of rift valleys
Plates move apart on continental areas. Brittle crust fractures as sections move apart. Areas of crust drop down between parallel faults to form the valley. MARS BAR
45
Characteristics of ocean ridge
Mid-Atlantic ridge Volcanic activity occurs Sea floor spread Sometimes volcanoes rise above ocean surface e.g. Iceland
46
Formation of ocean ridges
Plates move apart in oceanic areas Space between the plates is filled with basaltic lava upwelling
47
Characteristics of deep sea trenches
Associated with island arcs Mariana trench - 11000m deep
48
Formation of deep sea trenches
Oceanic and continental plates meet Oceanic plate subducts
49
Characteristics of island arcs
Long, curved chain of island Marianas islands - Guam Parallel to trench
50
Formation of island arcs
Destructive boundary Oceanic crust subducts which leads to formation of volcanoes which make islands.
51
Formation of Hot Spots
Concentrated decay in earth's core will form hotspots These heat the lower mantle creating localised thermal currents where magma plumes rise vertically. These plumes occasionally rise within the centre of plates and burn through the lithosphere to create volcanic activity on the surface As the hotspot remains stationary the movement of overlying plate results in the formation of a chain of active and subsequently extinct volcanoes as the plate moves away from the hot spot e.g. Hawaii
52
Arguments against hotspots
Bend in Emperor Seamount and Hawaiian ridge but no evidence to suggest that Pacific plate changed direction Mapping shows Iceland's hotspot would have been below Greenland but there's no island chain between Iceland and Greenland - (theory is that there was an old subduction zone which has now disappeared Too much magma for it to be just melted oceanic crust in Iceland
53
Causes of earthquakes
Movement of tectonic plates Building of large reservoirs Deep mining Fracking
54
Focus
Point at which pressure is released within curst Shallow focus will be felt stronger
55
Epicentre
Point on earth's surface immediately above the focus
56
Primary waves
Hit first Little impact on people
57
Secondary waves
Hit seconds after primary Higher impact as energy moves perpendicular to direction of movement which shakes the earth
58
Love waves
Slow and large Twist from side to side and make buildings vulnerable Travel along surface
59
Rayleigh waves
Very impactful Travel along surface Barrel roll
60
Richter Scale
Used to find how powerful an earthquake was Logarithmic scale from one to nine
61
Mercalli scale
Measures the intensity of an earthquake 12 increasing levels of intensity Subjective measure
62
Moment Magnitude Scale
Used by seismologists Used to compare size of earthquakes where Richter scale (which saturates for earthquakes > 7) isn't so accurate Measures energy released by earthquake
63
Primary impacts of seismic hazards
Ground shaking Ground rupture - breathing and displacement of the earth's surface
64
Secondary impacts of seismic hazards
Liquefaction Tsunami Fires - gas lines Flooding Landslide/avalanches Death Buildings collapsing Destruction of infrastructure
65
Liquefaction
Vibrations in saturated soil cause the particles to lose contact with each other and act as a liquid Soil is unable to support weight and cars can sink into it High risk on land reclaimed from ocean
66
Tsunami
Caused by shallow-focus underwater EQs + volcanic eruptions Have very long wavelength and a low wave height which rapidly increases when it reaches shallow water Travel at 700km/hour The wave will wash boats and wooden coastal structures inland, backwash may carry them out to sea Drowning Infrastructure washed away Impacts reach 500-600m inland
67
Prediction of EQs
Can't really predict EQs
68
Attempts to predict EQs
Observing unusual animal behaviour ↑ water level ↑ radon gas concentrations Foreshocks (can't tell if they're foreshocks or just small EQs)
69
Preparation and protection of EQs - Federal Emergency Management Agency
FEMA aims: Promotes understanding of EQs + impacts Work to better identify EQ risk Improve EQ-resistant design and construction
70
Preparation and protection of EQs - hazard resistant structures
Concrete counter-weight in top of buildings - Taipei 101 Rubber shock absorbers in the foundations Older buildings can be retrofitted
71
Preparation and protection of EQs - education
Individual preparation - securing homes, making 'emergency kits' EQ drills at school Japan has disaster prevention day US Red Cross - list of supplies for 3-day survival kit
72
Preparation and protection of EQs - fire protection
Smart meters can cut off gas if an EQ of sufficient magnitude occurs
73
Preparation and protection of EQs - emergency services
Training on procedure following EQ Computer programmes which identify which areas need emergency services the most
74
Preparation and protection of EQs - land use planning
Identifying hazardous areas - e.g. Christchurch + liquefaction - and not building essential infrastructure there
75
Preparation and protection of EQs - aid
Only focussed on helping days after - no long-term aid Provide medical services, tents, water purification equipment
76
Preparation and protection of EQs - tsunami protection
Can't be entirely predicted but early warning systems through networks of buoys which measure water pressure Fukushima tsunami wall was ineffective and nuclear plant was damaged - evacuation 20km radius
77
Active volcano
A volcano that has erupted within recorded history and is currently erupting or showing signs of unrest - Mauna Loa
78
Dormant volcano
Hasn't erupted in thousands of years but has the potential to erupt again - Mt. Kilimanjaro
79
Extinct volcano
Not going to erupt again - Arthur's Seat
80
Location of volcanoes
95% occur on fault lines - subduction zones, mid-ocean ridges, rift valleys 5% occur on hotspots
81
Viscosity of lava
Character of volcanoes is largely controlled by viscosity High viscosity lavas flow slowly and cover small areas Low viscosity lavas flow more rapidly and cover thousands of km^2 Low viscosity allows gases to escape easily, whereas gas pressures can build up inside high viscosity lava resulting in violent eruptions More silica → more viscous
82
Fissure volcano | Type of eruption, viscosity, acidity, type of rock, character, boundary
Icelandic Very low Basic Basaltic Effusive - lava flows gently from fissures Constructive and hotspots
83
Shield volcano | Type of eruption, viscosity, acidity, type of rock, character, boundary
Hawaiian Low Basic Basaltic Wide, gently sloping sides and frequent, none-violent eruptions Constructive and hotspots
84
Dome volcano | Type of eruption, viscosity, acidity, type of rock, character, boundary
Strombolian Low - higher than shield Basic Basaltic Explosive but not as strong as others Destructive
85
Ash-cinder volcano | Type of eruption, viscosity, acidity, type of rock, character, boundary
Vulcanian Middling Acidic Basaltic/andesitic More explosive, less frequent Destructive
86
Composite volcano | Type of eruption, viscosity, acidity, type of rock, character, boundary
Pelean High Acidic Andesitic/rhyolitic Steep, conical shape, violent eruptions, pyroclastic flow, lahars, ash clouds Destructive Andes
87
Caldera volcano | Type of eruption, viscosity, acidity, type of rock, character, boundary
Plinian Very high Acidic Rhyolitic Crater-like depression where magma chamber empties and collapses Several km in diameter Super-volcanic eruptions Destructive - Yellowstone
88
Volcanic Explosivity Index
Relative measure of the explosiveness of volcanic eruptions 0 = non-explosive 8 = very large
89
Pyroclastic Flow
Explosive volcanoes Fast-moving current of hot gas and rock which hugs the ground and travels downhill Speeds up to 700km/h, 1000C Doesn't spread too far Inhalation of gas causes instant death Mount Vesuvius - Pompeii
90
Lava Flow
Both explosive and effusive Between 1000-2000C Can easily be avoided by a person on foot Can't be stopped or diverted Often burn down vegetation + structures Can extend several km if the lava is basaltic Fast-moving lava engulfed 75% of 3 villages in 2014 Fogo eruption - Cape Verde
91
Tephra
Explosive Rock material ejected into the air - fine ash to large volcanic bombs Hazardous as it can cover agricultural land, destroying crops Cause airspace to be closed 2010 eruption of Eyjafjallajökull led to cancellation of 100,000 flights
92
Nuees Ardente
Explosive Similar to pyroclastic flow but denser and slower 1902 - Mount Peleé on Martinique killed 30,000 people
93
Ash fallout
Explosive Ash can rise up and form an eruption column up to 45km Can be transported by the wind over long distances Covers all buildings, roads and farms over thousands of kms and major disruption Poisons water sources Weight of ash can collapse buildings Eyjafjallajökull
94
Volcanic gases
Both CO, CO2, SO2 Silent and deadly threat to humans. Gases irritate eyes, nose, throat, lungs, and can mix with water vapour to form volcanic fog which can be dangerous to breathe 1986 - 1,200 people were killed when an underwater volcanic explosion let off deadly gases at Lake Nios, Cameroon
95
Mudlfows/lahars
Explosive Volcanic mudflows with consistency of wet concrete Form when ash, rock fragments and mud mix with water (usually snow melt) Travel up to 50km/h and consume everything in path 1985 - small eruption caused big lahar in Tolima, Guatemala and buried whole town - 25,000 deaths
96
Acid rain
Both SO2 combines with water in atmosphere Pollutes surface water, enhances weathering, and can damage crops Tonga 2022 - volcano has been releasing gas since eruption
97
Prevention of volcanoes
Can't prevent them from exploding Can prevent building close to volcano - exclusion zone around Soufriere Hills volcano in Montserrat
98
Monitoring and predicting volcanoes
Locating is straightforward Harder to predict when but still possible: - monitoring land swelling - changes in groundwater levels - changes in gas emissions (increased sulfur) - monitoring seismic activity
99
Preparation for volcanoes
Individuals can make plan to get to closest emergency shelter and make emergency kit Communities can prepare by risk-sharing and organising search and rescue teams
100
Mitigation of volcanoes
Engineering lava diversion barriers Cooling lava flows by spraying water to slow advancing lava - Iceland Ash collection and removal - clearing ash to prevent roof collapses Not building in an area susceptible to pyroclastic flow Channels to direct lahars into river channels - Japan
101
Adaptation to volcanoes
Strengthen buildings to prevent collapse from ash Buildings near Eyjafjallajökull are 50% stronger and have slanted roofs Capitalise on opportunities - farming, tourism - Iceland
102
Mitigation
Measures taken to reduce or prevent the negative impacts of hazardous events
103
Orogeny
Deformation of the lithosphere

Geography - Physical (15 decks)

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