Hazards (without case studies) Flashcards
1
Q
The concept of hazards in a geographical context
-Disaster description
A
-When a hazard causes a significant impact on a vulnerable population-> serious, widespread, social, economic, environmental losses exceeding the ability of the community to cope
2
Q
The concept of hazards in a geographical context
-Hazard description
A
-A perceived natural/geophysical event that has the potential to threaten life and property damage
3
Q
The concept of hazards in a geographical context
-Resilience
A
-The ability of a community to cope with, and recover from, the effects of a hazard in a timely and efficient manner; including through preservation and restoration of basic structures
4
Q
The concept of hazards in a geographical context
-Risk description
A
-The probability of a hazard occurring, creating loss of lives and/or livelihoods
5
Q
The concept of hazards in a geographical context
-Risk assessment description
A
-The likelihood of harm and damage and the anticipation of the type and scale of these
6
Q
The concept of hazards in a geographical context
-Vulnerability
A
-The reduced capacity of an individual or group to anticipate, cope with, resist and recover from the impact of natural or man-made hazards
7
Q
The concept of hazards in a geographical context
-Description of geomorphic hazards
A
- Geomorphic= Changes in land shape
- Hazard event= Landslide
8
Q
The concept of hazards in a geographical context
-Description of atmospheric hazards
A
- Atmospheric=storm hazards
- Hazard events= Tropical storms (typhoon), extra-tropical storm (over UK)
9
Q
The concept of hazards in a geographical context
-Description of hydrological hazards
A
- Hydrological= water/weather extremes
- Hazard events= Drought
10
Q
The concept of hazards in a geographical context
-Description of geophysical hazards
A
- Geophysical= All tectonic hazards
- Hazard events= Earthquake, tsunami
11
Q
The concept of hazards in a geographical context
-Description of biohazards
A
Biohazards= Hazards associated with plant and animal life
Hazard events= Wildfires
12
Q
The concept of hazards in a geographical context
-Hazard perceptions and concepts
A
Economic:
-If a country is poor/poorly developed, they will struggle to cope when the hazard hits (vice versa for developed countries)
Social:
-Poorer people who live in high density areas will suffer when a hazard hits because the infrastructure will not protect them. People in rural areas may become affected and could get cut off from aid from local services
Political:
-If the government is organised and sets out emergency plans and routes then the affects will be decreased
Technological:
-If there are accurate predictions from scientists, then local services can provide safety measures and evacuation paths in good time
13
Q
The concept of hazards in a geographical context
-Factors that affect how a community responds to a hazard
A
Human factors:
-Fatalism, prediction, adaptation, risk sharing, mitigation
Physical factors:
-Physical vulnerability, social vulnerability, hazard exposure
14
Q
The concept of hazards in a geographical context
-Park’s disaster-response model
A
- The Park model is also known as the disaster response curve
- It’s aim is it show the effects of a hazard on quality of life over a sequence of time
- There are 3 outcomes at the end: improvement, return to normality and deterioration
- The x- axis is time and the y-axis is quality of life
15
Q
The concept of hazards in a geographical context
-Disaster management cycle
A
- The are 4 main components: mitigation, preparedness, response and recovery
- The DMC aims to reduce, or avoid, the potential losses from hazards, assure prompt and appropriate assistance to victims of disaster, and achieve raid and effective recovery
- The 3 stages are: pre-disaster, disaster occurrence and post-disaster
16
Q
The concept of hazards in a geographical context
-Socio-natural disasters
A
-Socio-natural disasters are both natural and man-made e.g. fires, droughts and floods
17
Q
Plate tectonics
-Asthenosphere
A
Layer of the Earth immediately below the lithosphere and is hotter and weaker than the lithosphere
18
Q
Plate tectonics
-Collision zone
A
A type of convergent margin in which two continents or island arcs have collided
19
Q
Plate tectonics
-Convection currents
A
Heat generated by the breakdown of minerals in the mantle which is redistributed by by currents that rise at mid oceanic ridges
20
Q
Plate tectonics
-Fault line
A
A long crack in the surface of the Earth
21
Q
Plate tectonics
-Fold mountain
A
Are created where two or more of Earth’s tectonic plates are pushed together
22
Q
Plate tectonics
-Gravitational sliding (or ridge push)
A
A proposed driving force for plate motion in plate tectonics
23
Q
Plate tectonics
-Island arcs
A
A curving chain of volcanic islands occurring around the margin of ocean basins
24
Q
Plate tectonics
-Lithosphere
A
The outer cool, rigid and brittle layer of the Earth
25
Plate tectonics
| -Mantle
The zone lying between the Earth's crust and core
26
Plate tectonics
| -Oceanic ridges
An underwater mountain range, formed by plate tectonics
27
Plate tectonics
| -Rift valley
A lowland region that forms where Earth's tectonic plates move apart, or rift
28
Plate tectonics
| -Slab pull
Is part of the motion of tectonic plate caused by it's subduction
29
Plate tectonics
| -Subduction zone
Where Earth's tectonic plates dive back into the mantle, at rates of a few cm a year
30
Plate tectonics
| -Plate tectonic theory of crustal evolution
- The theory of plate tectonics states that the Earth's solid outer crust, the lithosphere, is separated into plates that move over the asthenosphere, the molten upper part of the mantle
- The data and observations by the Tharp-Heezen map became critical factors in the acceptance of the the theory because it revealed that the ocean floor wasn't flat and it was due to sea-floor spreading
31
Plate tectonics
| -Hot spots and magma plumes
- A hot spot is an area on Earth over a mantle plume or an area under the rocky outer layer of Earth. It is separated in the lower mantle and go up to 1000km below the Earth's surface. Example= Hawaiian islands
- Magma plumes are areas of hot, upwelling mantle. Magma generated by the hot spot rises through the rigid plates of the lithosphere and produces low viscosity volcanoes at the Earth's surface
32
Plate tectonics
| -Sea-floor spreading
- Sea-floor spreading occurs at divergent plate boundaries
- As tectonic plates slowly move away from each other, the heat from the mantle makes the the crust more plastic
- The less dense material rises, often forming a mountain on the sea floor
33
Plate tectonics
| -Convection currents
- Heat rising and falling inside the mantle creates convection currents generated by radioactive decay in the core
- The convection currents move the plates. Where convection currents diverge near the Earth's crust, plates move apart. Where convection currents converge, plates move towards each other.
34
Plate tectonics
| -Destructive plate margins
- At a destructive boundary, the plates are moving towards each other and they usually involve the continental plate and the oceanic plate
- The oceanic plate is denser than the continental plate and as they move together, the oceanic plate is forced underneath the continental plate
- The point at which this happens is called the subduction zone
- When the oceanic plate is forced below the continental plate, it melts to form magma and earthquakes are triggered
- As the plate is forced down, there will be a deep gap under the sea which is known as an ocean trench
35
Plate tectonics
| -Constructive plate margins
- At constructive plate margins, the plates move apart from one another.
- When this happens, the magma from the mantle rises up to make (or construct) new land in the form of a shield volcano
- The movement of the plates over the mantle can cause earthquakes
36
Plate tectonics
| -Conservative plate margins
- At a conservative plate margin, the plates move past each other or are side by side moving at different speeds
- As the plates move, friction occurs and plates become stuck. Pressure builds up because the plates are still trying to move
- When the pressure is released, it sends out huge amounts of energy, causing an earthquake
- The earthquakes at a conservative plate boundary can be very destructive as they occur close to the Earth's surface
- There are no volcanoes at a conservative plate margin
37
Plate tectonics
| -Characteristic processes: seismicity
- Seismicity refers to the frequency of earthquake activity in an area
- Earthquakes follow distinct patterns of distribution that follow fault line zones and reactivated fault zones
- The most violent earthquakes occur at low depths associated with subductive plates at convergent margins
38
Plate tectonics
| -Characteristic processes: vulcanicity
- Vulcanicity refers to all the various ways by which molten rock and gasses are forced into the Earth and onto it's surface
- It includes volcanic eruptions which lead to the formation of volcanoes, lava plateaus and geysers
39
Plate tectonics
| -Magma plumes and their relationship to plate movement
- Magma plumes are areas of hot, upwelling mantle
- As oceanic volcanoes move away from the hot spot with the migration of their tectonic plate, they cool and subside, producing older island chains
40
Volcanic Hazards
| -Formation of nuees
- A nuee ardente is a turbulent, fast moving cloud of hot gas and ash erupted from a volcano
- They form during explosive eruptions as columns of erupted material collapse or during non-explosive eruptions when volcanic rock collapses
41
Volcanic Hazards
| -Formation of lava flows
- Lava forms when magma erupts from a volcano
- As pressure is released, gases dissolved in the magma, bubble out of the composition of lava chambers
- Most lava flows are formed by the eruption of hot (1200 C) basalt magma
42
Volcanic Hazards
| -Formation of mudflows
- Mudflows can be caused by unusually heavy rains or a sudden thaw
- They consist mainly of mud and water plus fragments of rock and other debris, so they often behave like floods
- They can move houses off their foundations or bury a place within minutes because of incredibly strong currents
43
Volcanic Hazards
| -Formation of pyroclastic and ash fallout
- Pyroclastic flows are produced when large portions of the dome collapse and disintegrate
- Pyroclastic fallout consists of particles that have been ejected from vents and have travelled through the atmosphere before falling to earth or into water
- Fallout ash can also can be derived from elutriation of ash that boils up from pyroclastic flows as they travel across the land
44
Volcanic Hazards
| -Formation of acid rain
- Acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air
- These substances can rise very high into the atmosphere, where they mix with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain
45
Volcanic Hazards
| -Formation of tephra
- When a volcano explodes, it releases a variety of tephra including ash, cinders and blocks.
- These layers settle on the land and over time, sedimentation occurs incorporating these tephra layers into the fossil record
46
Volcanic Hazards
| -VEI
- The volcanic explosivity index (VEI) is a scale that describes the size of explosive volcanic eruptions based on magnitude and intensity
- The numerical scale (from 0 to 8) is a logarithmic scale, and is generally analogous to the Richter and other magnitude scales
47
Volcanic Hazards
| -Primary hazards
- Primary hazards are caused by the direct interaction of seismic wave energy with the ground
- Examples include: lava flows, pyroclastic flows, tephra and volcanic gases
48
Volcanic Hazards
| -Secondary hazards
- Secondary hazards are hazards that result from an initial event, but happen at a later date
- Examples include: landslides, tsunami, lahars and flooding
49
Volcanic Hazards
| -Response to volcanic hazards
- There are 4 things which have to be done to help reduce the impacts of volcanic hazards and their impacts, it includes:
- Preparation
- Mitigation (action to reduce the severity of the situation)
- Prevention
- Adaptation
50
Seismic Hazards
| -Types of waves (p waves)
- Primary waves
- Vibrate in the direction of travel
- Can pass through the Earth's liquid outer core
- Travels at the speed of sound (343m/per second)
- They can travel through any material including fluids
51
Seismic Hazards
| -Types of waves (s waves)
- Secondary waves
- Right angles to the direction of travel
- S-waves are located in the outer core
- Only 60% of p-waves speed
- The ground moves from side to side
52
Seismic Hazards
| -Types of waves (surface Lowe)
- Surface waves
- They move side to side in a horizontal plane
- Can only move along the surface of the Earth
- 90% of the s waves velocity
- They can induce turbulence below the ocean surface
53
Seismic Hazards
| -Earthquakes
- An earthquake is the shaking and vibration of the Earth's crust due to movement of the Earth's plates (plate tectonics)
- Earthquakes occur when tension is released from inside the crust
54
Seismic Hazards
| -Shockwaves
- A shockwave is an area of very high pressure moving through the air, earth or water
- It is caused by an explosion or an earthquake, or by an object travelling faster than sound
55
Seismic Hazards
| -Tsunamis
- Tsunamis are ocean waves triggered by large earthquakes that occur near or under the ocean
- They are caused by earthquakes at destructive plate boundaries
56
Seismic Hazards
| -Liquefaction
- Liquefaction takes place when loosely packed, water-logged sediments at or near the ground surface lose their strength in response to strong ground shaking
- Liquefaction occurring beneath buildings and other structures can cause major damage during earthquakes
57
Seismic Hazards
| -Landslides
- A landslide is defined as the movement of a mass of rock, debris, or earth down a slope
- Landslides are a type of 'mass wasting', which denotes any down-slope movement of soil and rock under the direct influence of gravity
58
Seismic Hazards
| -Measuring seismic events
- Most seismic events are measured by the Richter Scale. This scale measures from 0 to 10 , where 10 is extreme destruction
- The Richter Scale describes the magnitude by measuring the seismic waves
- One advantage is that it allows experts to use more accuracy when comparing the EQ over time
- However one disadvantage is that, it does not provide accurate estimates for large magnitude earthquakes
59
Seismic Hazards
| -Primary hazards/impacts
- Ground shaking
- Ground ruptures
- Shock waves
60
Seismic Hazards
| -Secondary hazards/impacts
- Landslides
- Fires
- Soil liquefaction
- Avalanches
- Tsunamis
- Building collapse
61
Seismic Hazards
| -Social, political, environmental and economic impacts
Social:
- Transport and communication links may become disrupted
- People may be killed or injured
- Homes may be destroyed
Political:
- Pre existing conflicts may become more severe
- Increase the likelihood of conflict
Environmental:
- The built landscapes may become destroyed
- Fires can spread due to gas pipe explosions
- Landslides can occur
- Fires can damage areas of woodland
Economic:
- The cost of rebuilding settlements is high
- Investment in the area may be focused only on repairing the damage caused by the earthquake
62
Seismic Hazards
| -Responses to Hazards (preparation)
- Check for hazards in the home
- Identify safe places indoors and outdoors
- Educate yourself and family members
- Develop an emergency communication plan
63
Seismic Hazards
| -Responses to Hazards (Mitigation)
- Seek shelter under stable tables or door frames
- Of outside, stay away from buildings, bridges and move to open areas
- Avoid areas at risk of secondary hazards
64
Seismic Hazards
| -Responses to Hazards (Prevention)
-You cannot prevent natural earthquakes from occurring, but you can build safer structures and provide education on earthquake safety
65
Seismic Hazards
| -Responses to Hazards (Adaptation)
- Strapping water heaters to wall studs
- Putting latches on kitchen cabinets
- Using straps and buckles to anchor electronics and small appliances
66
Storm Hazards
| -Causes (sea temperatures)
-A source of warm, moist air derived from tropical oceans with sea surface temperatures normally in the region of 27 C+
67
Storm Hazards
| -Causes (latitude)
-They occur between 5 C and 30 C North and South of the equator due to the temperatures in these areas
68
Storm Hazards
| -Causes (coriolis force)
-The coriolis force is the deflection of objects (planes, winds, ocean currents) moving in a straight path relative to the Earth's surface
69
Storm Hazards
| -Causes (rising air/ low pressure)
-The faster the winds blow, the lower the air pressure in the centre, and so the cycle continues. The hurricane then grows stronger and stronger
70
Storm Hazards
| -Causes (low-level convergence of air)
-There is a process that produces low level convergence that is needed to initiate a hurricane
71
Storm Hazards
| -Forms of a storm hazard (high winds)
- Hurricane-force winds, 74mph or more, can destroy buildings and mobile homes
- Debris such as signs are thrown around
- Buildings can become destroyed
- Emergency plans and evacuations must be put in place
72
Storm Hazards
| -Forms of a storm hazard (heavy rainfall)
- Widespread torrential rains in excess of 6 inches, which can result in deadly and damaging floods
- People living inland are at threat to flooding from the torrential rainfall
73
Storm Hazards
| -Forms of a storm hazard (storm surges)
- Is an abnormal rise of water generated by a storms' wind
- Storm surges and battering waves cause destruction
- Impacts include; loss of life, building destruction and beach and dune erosion
74
Storm Hazards
| -Forms of a storm hazard (flooding)
- Flash flooding can occur quickly due to intense rainfall
| - When approaching water on roads, people are reminded 'turn around, don't drown'
75
Storm Hazards
| -Forms of a storm hazard (rip currents)
- Channelled currents of water flowing away from shore, that can pull the strongest swimmers away from shore
- It can kill people
- An example is Hurricane Bertha, which involved 3 deaths and 1,500 lifeguard rescues over a 1 week period
76
Storm Hazards
| -Saffir-Simpson Scale
- In the 1970's, Herbert Saffir developed a scale to describe the likely effects that hurricanes could have on an area
- The scale has 5 categories, increasing in intensity from 1 to 5
77
Storm Hazards
| -Risk Management (preparation)
- Education about dangers
- Preparation involves evacuation routes
- Emergency kits and shelters
78
Storm Hazards
| -Risk Management (prevention)
-Satellite and radar technology are used to track the development and approach of a tropical storm
79
Storm Hazards
| -Risk Management (adaptation)
- Designing buildings with secure roofs which use reinforced concrete
- Raise buildings on stilts
- Build sea walls along the coast
80
Storm Hazards
| -Risk Management (mitigation)
-Build new homes and businesses away from areas at risk, such as the coast
Train emergency services on how to react to a storm
81
Storm Hazards
| -Primary impacts of storm hazards
-The primary effects of a tropical storm are the immediate impacts of strong winds, heavy rainfall and storm surges. These include:
-People injured or killed by debris blowing around
-Drowning
-Buildings destroyed or damaged
-Electrical supplies cut off due to power lines being destroyed
Sewage released due to flooding
82
Storm Hazards
| -Secondary impacts of storm hazards
- Secondary effects are the impacts following the storm. This can include:
- People being left homeless
- A lack of clean water and sanitation
- Road and rail networks can be blocked by debris, making it difficult to provide support and aid for people affected
- Unemployment cause by businesses being damaged
83
Storm Hazards
| -Immediate responses to tropical storms
Immediate responses occur before the storm is forecast to make landfall and immediately after the event:
- People are evacuated before the storm lands
- Rescue people trapped and provide medical support for injured people
- Temporary shelters are set up for people made homeless by the storm
- Provide water and food for people
84
Storm Hazards
| -Long-term responses to tropical storms
Long term responses involve returning an area to the way it was before the storm and preparing for future storms:
- Repair and rebuild properties
- Rehouse people
- Repair the transport infrastructure
- Improve forecasting and early warning systems
85
Fires in Nature
| -Nature of wildfires
- A wildfire is an uncontrolled fire that burns in the wildland vegetation, often in rural areas
- Wildfires can burn in forests, grasslands, savannas, and other ecosystems, and have been doing so for hundreds of millions of years
- They are not limited to a particular continent or environment
86
Fires in Nature
| -Conditions favouring intense wild fires
- Wildfires usually occur in dry vegetation, where there are elevated temperatures and low winter-time precipitation that often leave vegetation primed for wildfires
- This was the case in California in 2021, which experienced a 65% rise in dry vegetation in just a few months
87
Fires in Nature
| -Wildfire causes
```
Bushfire causes in Victoria : 20 year average
-Lightning 26%
-Deliberate 20%
-Agricultural escapes 16%
-Campfires 10%
(the other 28% come from other causes)
```
88
Fires in Nature
| -Wildfire causes (human and natural)
Natural:
- Volcanic eruptions
- Spontaneous fires
- Underground coal fires
- Dry lightning storms
- Rockfall sparks
```
Human:
-Cigarette stubs
-Campfires/ bonfires
-Equipment related fires
-Arson for land clearing
Global warming
```
89
Fires in Nature
| -Primary impacts of wildfires
-Loss of life and injury to people and animals
-Destruction of property and possessions
-Loss of vegetation and crops
Smoke
90
Fires in Nature
| -Secondary impacts of wildfires
- Homelessness
- Health problems
- Loss of animal habitats
- Increased soil erosion
- Insurance premiums rise
91
Fires in Nature
| -Social impacts
- Blocked roads and railway lines
- Electricity, mobile and land telephone lines cut
- Destruction of homes and industries
92
Fires in Nature
| -Environmental impacts
- Wildfires release large quantities of carbon dioxide, carbon monoxide and fine particular matter into the atmosphere
- Resulting air pollution can cause a range of health issues, including respiratory problems
93
Fires in Nature
| -Economic impacts
-An economic study has estimated that each additional day of smoke exposure from a wildfire reduces earnings in a community by around 0.04% over 2 years
94
Fires in Nature
| -Political impacts
-Laws have to be changed about wildfire causes, such as BBQ's in summers
95
Fires in Nature
| -Wildfire hazards response (before the event)
Before the event:
- Discuss what to do if a bushfire threatens your home
- Prepare your home and get it ready for fire season -> simple things such as keeping the grass low and having a cleared area around your home
96
Fires in Nature
| -Wildfire hazard response (during a fire)
- Know the bush fire alert levels -> keep track of the alert level so you are prepared
- Keep all of the bush fire information numbers, websites and the smartphone app-> during a bush fire, it is important to stay up to date on the conditions in your area
