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PMT Hazardous Environments Flashcards

1
Q

Global distribution of tectonic hazards

A

Tectonic hazards are caused by the movement of tectonic plates. These usually occur on plate boundaries where two tectonic plates meet each other. Volcanoes occur on convergent plate boundaries and divergent boundaries. Earthquakes occur on all types of boundaries

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2
Q

Earthquakes

A

When plates become stuck due to friction the convection currents in the asthenosphere continue to push which builds the pressure. It cannot be sustained and the plates eventually give way. All of this pressure is released in a jolting motion which is responsible for seismic movement spreading as seismic waves. The focus is the point underground where the earthquake originates from. The epicentre is the area above ground that is directly above the focus

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3
Q

Magnitude of earthquakes

A

Seismicity is measured using the logarithmic Richter Scale which measures the strength of seismic waves. The Modified Mercalli Intensity Scale is a rate of the destruction caused. It has a definitive end. The Mercalli scale is subjective meaning sometimes it is disputed as it is dependent on human development being present rather than the strength of the seismic waves. The magnitude is also dependent on the depth of focus. Conservative boundaries have the shallowest boundaries so are closer to the epicentre and the seismic waves are stronger. Convergent boundaries have deeper focuses so waves are spread over a larger area before they reach the epicentre

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4
Q

Frequency of earthquakes

A

Earthquakes are frequent and hundreds of smaller magnitude earthquakes that cannot be felt occur daily

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5
Q

Regularity of earthquakes

A

Earthquakes follow no pattern and are random so there is irregularity between events

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6
Q

Predictability of earthquakes

A

Earthquakes are almost impossible to predict. Micro quakes may give some indication but the magnitude cannot be predicted as how strong they are is random

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7
Q

Shockwaves

A

When plates move friction builds up and pressure increases which is stored as potential energy. The energy that has been built up is transferred to kinetic energy which is released and vibrates throughout the ground. The further from the focus, the weaker the shockwaves as energy is transferred into surroundings

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8
Q

Tsunamis

A

When an oceanic crust is jolted during an earthquake all of the water above this plate is displaced. The water travels fast but with a low amplitude. As it gets closer to the coast the water becomes shallower forcing the waves to become compressed into a smaller area. This causes the waves to slow down and gain height creating a wall of water

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9
Q

Liquefaction

A

When soil is saturated the vibrations of an earthquake case it to act like a liquid. Soil becomes weaker and more likely to subside when it has large weight on it

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10
Q

Landslides and avalanches

A

Movement in soil or snow will cause it to become unstable. This can cause huge areas to give way sending large amounts of debris or snow to tumble downhill. This can damage infrastructure and buildings, damage the environment and poses a large threat to life

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11
Q

Primary environmental seismic hazard

A

Earthquake can cause fault lines which destroy the environment
Liquefaction

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12
Q

Secondary environmental seismic hazard

A

Radioactive materials and other dangerous substances leaked from power plants
Saltwater from tsunamis flood freshwater ecosystems
Soil salinisation

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13
Q

Primary economic seismic hazard

A

Businesses destroyed
Immediate payout for response

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14
Q

Secondary economic seismic hazard

A

Economic decline as businesses are destroyed
High cost of rebuilding and insurance payout
Sources of income lost

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15
Q

Primary social seismic hazard

A

Buildings collapse, killing or injuring people and trapping them
Homes destroyed

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16
Q

Secondary social seismic hazard

A

Gas pipes rupture, starting fires which can kill
Water supplies are contaminated as pipes burst, spreading disease and causing floods
Tsunamis which lead to damaging flooding

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17
Q

Primary political seismic hazard

A

Government buildings destroyed

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18
Q

Secondary political seismic hazard

A

Political unrest from food shortages or water shortages
Borrowing money for international aid
Can be initial chaos and lawlessness

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19
Q

Prevention of seismic hazards

A

Most cannot be prevented. Earthquakes and tsunamis will occur regardless
Liquefaction of soils can be prevented through soil stabilisation
Avalanches can be prevented through controlled explosions

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20
Q

Preparedness of seismic hazards

A

Earthquake prone areas have extensive awareness strategies and education in place
Earthquake warning systems and tsunami warning systems after an earthquake
Evacuation plans and training

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21
Q

Mitigation of seismic hazards

A

Search and rescue, immediate emergency aid, evacuation
Demolishing older, unsafe buildings
Tsunami wave breaks and sea walls

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22
Q

Adaptation to seismic hazards

A

Move away from area at risk
Capitalise on opportunities such as encouraging tourism
Insurance if living in places of risk
Changing lifestyle choices
Building specially designed earthquake proof buildings

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23
Q

Volcanoes on convergent plate boundaries

A

Usually explosive due to the high pressure the magma is under. Composite volcanoes made from ash and lava are formed from these eruption

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24
Q

Continental and oceanic volcanic eruptions (convergent)

A

Denser oceanic plate subducts below the continental
The plate subducting leaves a deep ocean trench
Fold mountains occur when sediment is pushed upwards during subduction
The oceanic crust is melted as it subducts into the asthenosphere
The extra magma created causes pressure to build up
Pressurised magma forces through weak areas in the continental area
Explosive, high pressure volcanoes erupt through the continental plate called composite volcanoes

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25
Oceanic and oceanic volcanic eruptions (convergent)
Heavier plate subducts leading an ocean trench. Fold mountains will also occur Built up pressure causes underwater volcanoes bursting through oceanic plate Lava cools and creates new land called island arcs
26
Volcanoes on divergent plate boundaries
Usually effusive as the magma is under less pressure so the lava flows more freely. Shield volcanoes made mainly from lava are formed from these eruptions
27
Oceanic and oceanic volcanic eruptions (divergent)
Magma rises in between the gap left by the two plates separating forming new land when it cools Less explosive underwater volcanoes formed as magma rises New land forming on the ocean floor by lava filling the gaps is sea floor spreading
28
Continental and continental volcanic eruptions (divergent)
Any land in the middle of the separation is forced apart causing a rift valley Volcanoes from where the magma rises Eventually the gap will most likely fill with water and separate completely from the main island The lifted areas of rocks are known as horsts whereas the valley itself is known as a graben
29
Volcanoes on hotspots
Hotspots are areas of volcanic activity that are not related to plate boundaries. Hot magma plumes from the mantle rise and burn through weaker parts of the crust. This can create volcanoes and islands. The plume stays in the same place but the plates continue to move which sometimes causes a chain of islands
30
Lava flows
Lava can flow quickly or slowly depending on its viscosity. Silica makes lava viscous and slow which is common in explosive eruptions
31
Lahars
Caused mainly due to melting ice at high latitudes
32
Mudflows
Lahars are volcanic material while mudflows may be triggered by the violent shaking that en eruption brings or meltwater from the volcanic heat
33
Glacial floos
When temperatures are high from lava glaciers or ice sheets at high temperatures quickly melt and a large amount of water is discharged
34
Tephra
Any type of rock that is ejected by a volcano
35
Toxic gases
Released during some eruptions
36
Acid rain
Caused when gases such as SO2 are released into the atmosphere
37
Volcanic landslides
High velocity flows of debris caused when the energy from the eruption blows apart rocks and other material sending it down the volcanic slope
38
Nuees ardentes and pyroclastic flows
Clouds of burning hot ash and gas that collapses down a volcano at high speeds
39
Magnitude of volcanoes
Vulcanicity is measured with the Volcanic Explosivity Index. The more powerful, the more explosive. The scale is logarithmic. Multiple features are considered including how much tephra is erupted, how long it lasts, how high the tephra is ejected. Intense high magnitude eruptions are explosive whereas calmer, lower magnitude eruptions are effusive
40
Frequency of volcanoes
Varies per volcano. Volcanoes are classed as either active, dormant or extinct. 50-60 volcanoes erupt each month so volcanic eruptions are always frequency. Usually a higher frequency means the eruptions are effusive whereas low frequency means the eruptions are explosive
41
Regularity of volcanoes
Volcanic eruptions are regular in that the eruptions on each type of boundary are similar
42
Predictability of volcanoes
Regularity can estimate when eruptions take place. Seismic activity, gases releasing and elevation can all indicate an imminent eruption but there is no definite predictions
43
Primary environmental volcanic hazard
Ecosystems damaged through various volcanic hazards Wildlife killed
44
Secondary environmental volcanic hazard
Water acidified by acid rain Volcanic gases contribute to greenhouse effect
45
Primary economic volcanic hazard
Businesses and industries destroyed or disrupted
46
Secondary economic volcanic hazard
Jobs lost Profit from tourism industry
47
Primary social volcanic hazard
People killed Homes destroyed from lava and pyroclastic flows
48
Secondary social volcanic hazard
Fires can start which put lives at risk Mudflows or floods Trauma Homelessness
49
Primary political volcanic hazard
Government buildings and other important areas destroyed or disrupted
50
Secondary political volcanic hazard
Conflicts concerning government response, food shortages and insurance
51
Prevention of volcanic hazards
Volcanic eruptions cannot be prevented Only the risk to people can be prevented by not allowing people near volcanic hazards
52
Preparedness of volcanic hazards
Monitoring increases the notice of volcanic eruptions meaning warnings can be given out Education on volcanoes in areas of risk so people know what to do if there is a volcanic eruption Evacuation procedures planned Training response teams
53
Mitigation of volcanic hazards
Direct intervention to the volcano Strengthening buildings that are at risk of mudflows or ash pileup Evacuation and exclusion zones Mitigating effects on health but having emergency aid and rescue
54
Adaptation to volcanic hazards
Move away from area at risk Capitalise on opportunities such as encouraging tourism Change profession so it is less likely to be affected by volcanic hazards
55
Mass movements
The large scale movement of materials on a hill slope caused when the stress exerted exceeds the internal strength of the slope causing instability. Will always be downhill due to the force of gravity. These can happen over a range of timescales and also depend on the moisture in the slope material
56
Causes of mass movements
Occur due to slope instability due to an increase in external stress or a decrease in internal strength. Slope may become too saturated. Weathering and erosion can weaken the internal strength until it can no longer bear the load. Seismic waves may cause mass movement processes. Multiple human activities can add stress or remove its strength
57
Predictability of mass movements
Precipitation levels can be measured through a rain gauge or radar showing the risk of movements triggered by heavy rainfall. Soil moisture content can be measured by different technologies. Changes in slope surface can be detected with radars and inclinometers. Seismometers measure seismic waves which can indicate whether there is a risk of a mass movement
58
Primary environmental mass movement hazard
Ecosystems damaged through destroyed slope Wildlife killed Damage to environment
59
Secondary environmental mass movement hazard
Debris and mud can block waterways and cause other environmental issues
60
Primary economic mass movement hazard
Businesses and industries destroyed or disrupted
61
Secondary economic mass movement hazard
Jobs lost Money needed to rebuild and clean up Investments into slope stability
62
Primary social mass movement hazard
People killed or injured Homes destroyed Roads blocked Infrastructure destroyed
63
Secondary social mass movement hazard
Power outages and gas leaks caused by broken infrastructure Blocked roads Trauma Homelessness
64
Primary political mass movement hazard
Government buildings and other important areas destroyed or disrupted
65
Secondary political mass movement hazard
Conflicts or disagreements concerning government response
66
Prevention of mass movements
Reinforcement of the slope Rock bolting Afforestation Pining and nailing Grading These can also be considered mitigation depending on their success
67
Preparedness of mass movements
Evacuation plans and response plans in place Early warning systems using monitoring techniques so that strategies can be put in place if there are indications of mass movement
68
Mitigation of mass movements
Search and rescue, immediate emergency aid and evacuation Steel netting to catch rockfalls and debris Hazard mapping can be used to allocate areas for building and monitoring
69
Adaptation to mass movements
Move away from area at risk Insurance if living in places of risk Limit activities that make slopes more unstable such as agriculture, logging, ski tourism, mining and construction
70
Temperature tropical storm formation and development condition
Ocean temperatures must be around 26-27C and at least 60m deep. Warm water provides the storm with energy
71
Air pressure tropical storm formation and development condition
Must be in areas of unstable air pressure usually where areas of high pressure and low pressure meet so that warm air rises more readily and clouds can form. Warm air rises because it is less dense than cold air
72
Wind shear tropical storm formation and development condition
Winds must be present for the swirling motion to form but not too strong or the storm system will be ripped apart in the early stages
73
Rotation tropical storm formation and development condition
Tropical storms only form around the equator but not less than 5 degrees on either side. The Coriolis Effect is the effect of the earths rotation on weather events. The storm spins because the earth is spinning but there is no Coriolis Effect at the equator hence why these storms will only form a certain distance away from it
74
A trigger tropical storm formation and development condition
A pre existing thunderstorm, s spot of very high sea surface temperature, an area of low pressure and many other factors can act as a trigger for a storm to develop which will only further develop when the other conditions are present
75
Formation of tropical storms
Warm, moist air rises leaving an area of low pressure below. This causes warm air from surrounding areas of higher pressure to move into this low pressure area and rise. Warm air is constantly rising and accumulating. When the warm air rises it cools, condensing into thunderstorm clouds. The Coriolis effect causes the whole system to spin (clockwise in SH and anticlockwise in NH). Additions of energy from warm air causes faster spinning generating higher winds. The difference in pressure between low pressure centre and high pressure surrounding causes air to be sucked towards the centre enhancing high winds. The eye is in the centre at extremely low pressure. Cool, dry air descends causing calm and cloud free weather. Surrounding the eye is the eye wall, the most intense and powerful area. Warm, moist air rapidly rises with very high winds and rain. When it reaches a coast the low pressure and high winds cause seawater to be taken into the system and released as a storm surge. When it reaches land it no longer has an energy supply and collapses
76
Magnitude of tropical storms
Measured on the Saffir-Simpson Scale based on wind speed and power
77
Frequency of tropical storms
Form in the NH from June to November and the SH from November to April. Most do not develop into strong storms and do not reach land. Those that are higher magnitude and reaching land are increasing in frequency
78
Regularity of tropical storms
Irregular because although they occur in the same areas their path doesn't follow a set route which is dependent on the storm and the climatic conditions
79
Predictability of tropical storms
Form away from land meaning satellite tracking of cloud formations and movement can be tracked and the general route can be predicted. The closer the hurricane gets the easier it is to predict. Storm surges can be predicted based on the pressure and the intensity of the storm. The probability of a storm hitting an area can be predicted from past storms and climatic trends
80
Hazards caused by tropical storms
High winds over 300 km/h strong enough to blow debris Flooding from storm surges and heavy rain Landslides due to soil becoming heavy when wet with high levels of rain Storm surges due to low pressure and high winds pushing water towards the coast
81
Primary environmental storm hazard
Beaches eroded Sand displaced Coastal habitats such as coral reefs are destroyed
82
Secondary environmental storm hazard
River flooding and salt water contamination Animals displaced from flooding Water sources changing course from blockages
83
Primary economic storm hazard
Businesses destroyed Agricultural land damaged
84
Secondary economic storm hazard
Rebuilding and insurance payout Sources of income lost Economic decline from sources of income destroyed
85
Primary social storm hazard
Drowning Debris carried by high winds can injure or kill Buildings destroyed
86
Secondary social storm hazard
Homelessness Polluted water supplies spread disease Food shortages from damaged land
87
Primary political storm hazard
Government buildings destroyed
88
Secondary political storm hazard
Issues paying back international aid Pressure for government to do more about global warming
89
Prevention of storm hazards
In current climates and weather conditions tropical storms cannot be avoided Strategies to mitigate climate change could prevent higher category storms
90
Preparedness of storm hazards
Awareness through education of what to do during a tropical storm Evacuation plans and training Satellite image tracking to manage the areas that are at risk Storm warning systems and television broadcasts tracking the storm
91
Mitigation of storm hazards
Search and rescue, immediate emergency aid and evacuation Strengthening the home through door barricades and roof strengthening Clearing loose debris before storms
92
Adaptation to storm hazards
Move away from area at risk Design buildings to withstand high winds and flood damage Flood defences such as houses on stilts, coastal walls and river levees
93
Tornadoes
A tornado is a violently rotating moving vortex of air. Found in many areas across the world especially within the middle latitudes
94
Formation of tornadoes
When the sun heats the ground the hot air rises and then condenses into clouds. Higher winds must be stronger and faster than winds lower down. The stronger, faster wind may start to roll under the weaker wind creating a horizontal cylinder of wind. As the powerful hot updraughts of air continue to rise they can the cylinder to be forced upwards into a rotating vertical column of air (supercell). Cool, dry downdraughts of air pull the rotating air downwards causing the spinning vortex to spin faster and become tighter. If it reaches the ground it is then a tornado
95
Magnitude of volcanoes
The Enhance Fujita Scale is used to rate the intensity of a tornado based on the damage it cases
96
Frequency of volcanoes
Most frequency in spring and rare in winter
97
Predictability of volcanoes
Favourable conditions for a tornado to develop can be monitored. Warning signs may be sighted such as funnel clouds or a rear flank downdraft. Radars and weather systems can spot signs of a tornado forming or if already on the ground. A Doppler Radar detects a large rotating updraft in a supercell based on its shape
98
Hazards caused by tornadoes
High winds also blow heavy debris at high speeds. Precipitation and flooding due to extremely heavy rain leading to landslides and hail. Pressure imbalance which can damage houses
99
Primary environmental tornado hazard
Destruction of habitats from high winds and rain Wildlife killed or injured
100
Secondary environmental tornado hazard
Flooding from heavy rain Landslides or other natural structural failures due to tornado and its storm Animals displaced due to destroyed habitats
101
Primary economic tornado hazard
Businesses destroyed Agricultural land damaged
102
Secondary economic tornado hazard
Rebuilding and insurance payout Sources of income lost Economic decline from sources of income destroyed
103
Primary social tornado hazard
Debris carried by high winds can injure or kill Homes and other buildings destroyed
104
Secondary social tornado hazard
Widespread power failure Psychological trauma as a result Homelessness Risk of injury due to destroyed house
105
Primary political tornado hazard
Government buildings destroyed
106
Secondary political tornado hazard
Issues paying back international aid Pressure on government to provide aid
107
Prevention of tornado hazards
There are no known ways to prevent a tornado from occurring Risk to life can be prevented entirely by not living in tornado prone areas
108
Preparedness of tornado hazards
Tornado warning systems in place Evacuation plans, drills and training Back up generators and supplies ready in case of a tornado
109
Mitigation of tornado hazards
Search and rescue, immediate emergency aid and evacuation Turning off gas, electricity and water to limit risk after a tornado Stronger power lines to reduce power outages
110
Adaptation to tornado hazards
Move away from area at risk Insurance if living in places of risk Building infrastructure and buildings to withstand tornadoes Purpose built tornado shelters or storm cellars
111
Hazard perception
People have different viewpoints of how dangerous hazards are and what risk they pose. These are dependent on lifestyle factors which include economic and cultural elements
112
Wealth hazard perception
The financial situation of a person will affect how they perceive hazards. Wealthier people may perceive a hazard to be smaller as they are less vulnerable. However they may also view a risk as greater as there is more risk of property damage and financial loss than someone less wealthy
113
Experience hazard perception
Someone who has experienced more hazards may be more likely to understand the full effects of a hazard. People who have experienced hazards are likely to have an optimistic and unrealistic outlook on future hazards
114
Education hazard perception
A person who is more educated about hazards may understand their full effects on people and how devastating they can be and have been in the past. Those who are less educated may not understand the full extent of a hazard and may not evacuate
115
Religion and beliefs hazard perception
Some may not perceive hazards to be negative. Those who believe strongly in environmental conservation may perceive hazards to be a huge risk to the natural environment especially those that are becoming more frequent due to global warming
116
Mobility hazard perception
Those who have limited access to escape a hazard may perceive hazards to be greater threats than they are. Whether they are in a secluded location or if they are impaired with a disability or illness or those who cannot easily leave an area quickly may feel more at risk

Geography review (8 decks)

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