Hazards- content Flashcards
What is a hic?
A high income country
What is a lic?
A low income country
What is a nec?
A newly emerging country
Describe what a hazard is
“natural events that are perceived to threaten life/property/ the built environment and the natural environment
What is perception?
The way in which an individual or group views the threat of a hazard event
What is a disaster?
Exceeds the ability of the affected community to cope using its own resources
What are geophysical processes?
Processes that are driven by the earths internal energy
What are atmospheric processes?
Driven by processes that work in the atmosphere
What are hydrological processes?
Driven by water bodies (mainly oceans)
Give an example of atmospheric processes
- hurricane/typhoon
- storm
- tornado
- lightening
- drought (leading to fires)
Give examples of geophysical processes
- volcano
- earthquakes
- tsunami
- rockfall
Give examples of hydrological processes
- tsunamis
- flood (river+coastal)
- drought
- storm surges
- avalanches
How do natural hazards share common characteristics?
- origins are clear and their effects are distinctive
- often they occur with little warning
- exposure to the risk may be involuntary especially in less developed areas
- most damage and loss of life occurs shortly after hazards but impact may last
- their scale and intensity requires an emergency response
What is risk?
“the exposure of people to a hazardous event presenting a potential threat to themselves, their possessions and the built environment in which they live
Why risk it?
- )Hazards are unpredictable
- )Lack of alternatives
- )The level of risk changes
- )Cost/benefit
- )Perception
Why risk it? Describe how hazards are predictable
Cannot predict frequency, magnitude or scale of a natural hazard event
Why risk it? Describe how there are a lack of alternatives
People can’t uproot themselves and move to another place
Why risk it? Describe how the level of risk changes
Places that were once relatively safe may have become more of a risk
Why risk it? Describe cost/benefit
May be advantageous e.g California
Why risk it? Describe perception
It is related to how much people view the threat of a hazard
Hazard risk, perception and vulnerability: What is popocatapeti?
A volcanic mountain less than 50 miles from Mexico City in Mexico. Mexico has a population of over 8.8m people
Hazard risk, perception and vulnerability: What is Mt. Vesuvius?
An active volcano near the city of Naples, Italy. It is a realistic threat for about 3 million people who live in Naples and surrounding towns
What is acceptable risk?
The level of potential losses that a society of community considers acceptable given existing social, economic, political, cultural, technical and environmental conditions
What is vulnerability?
The potential for loss- it is spatial, temporal and social
What are the 4 key approaches?
- )Fatalism
- )Adaptation
- )Fear
- )Domination
What is fatalism?
- natural events that are part of living in an area
- ‘gods will’ (losses are inevitable)
- people remain where they are and any action is direct and concerned with safety but on the whole preventative measures are limited or non existent
What is adaptation?
people see that they can prepare and therefore survive the events by prediction, prevention and/or protection
What is fear?
Move away (no longer able to face living in the area)
What is domination?
- scientific research
- control is possible through engineering or use of technology
What factors affect people perception of a hazard?
- religion
- different cultures and nations
- the socio-economic situation of people
- media
- trust we have in abilities of the responsible person
- individual values and personality
How does religion affect perception of a hazard?-give an example
- The people inhabiting tornado regions of Alabama, USA are largely convinced that what happens to them depends on God or good fortune.
- In contrast the inhabitants of Illinois, USA who are exposed to a similar threat believe it is all about their own behaviour that determines their fate. Accordingly they have implemented provocative measures that have considerably reduced the number of deaths caused by storm disasters in Illnois versus Alabama
Give an example of comparisons between different cultures and nations that have been made in the past
- Between Americans and Japanese
- Such studies revealed a difference in the perception of Japanese and Americans in relation to nuclear risks
- The Japanese tend to view nuclear risks as being higher, but the voluntariness to exposure to the risk is also viewed as being higher than it is by Americans
How does the socio-economic situation of people affect peoples perceptions of hazards?
Mexican field workers whose economic situation leaves extremely little leeway for action, have stated that they do not worry about health impairments caused by pesticides at work
How is media used as one of the main tools to amplify (inc.) or attenuate (reduce) a certain risk topic?
- if the media report a risk, many people become suddenly aware of it and start to worry
- if a risk topic appears in the media e.g news then the risk must be real because it has made it into the media
- in terms of numbers, a media-covered risk might be negligible, like the post-september 11 anthrax threats to US politicians and citizens if compared to other risks that are less extensively covered
What is preparedness?
Large scale events can be rarely prevented from happening, but education and raising public awareness can reduce the human causes and adjust behaviour to minimise the likely impact of the hazard. Knowing what to do can speed up the recovery process
What is response?
The speed of the response will depend on the effectiveness of the emergency plan that has been put in place. Immediate responses focus on saving lives and co-ordinating medical assistance. Damage assessment haps plan for recovery
What is recovery?
Restoring the affected area to something approaching normality
What is mitigation?
- Actions aimed at reducing the severity of an event and lessening its impacts
- This can involve direct intervention such as a building design that can withstand earthquakes or hurricanes
- Most desirable is the long term protection of natural barriers such as coral reefs which protect the shore against storm surges
- Support after a disaster in the form of aid and insurance can reduce long term impacts. Insurance may not be available in high risk areas.
What are the 4 elements of the disaster management risk cycle?
- preparedness
- response
- recovery
- mitigation
When was the park model established?
1991
What are the uses of the park model?
- speed of response and the effectiveness of the response can be measured by the curve
- the model reflects the nature of how it recovers and when, this is important for future planners
- a park model curve allows for visual comparison between different places
- it’s a versatile model, it can be used for an array of disasters
What are the limitations of the park model?
- the model does not take anything into account that happened before the event, for example any planning/mitigation/management. therefore it is hard to learn from the successes of planning as they are not visible on this model
- the curve reflects a single event for a single area and ignores the nuances nature of a disaster
- the model doesn’t account for spatial variation as it assumes all parts of a country recover at uniform rate. Thus, the curve is not an accurate representation of the entire country
- no quantitative data is recorded (number of deaths/damage to the economy)
- the model can not be used effectively for more than 1 event. E.g hurricane Irma, the model requires multiple curves which is inconvenient
Why do rocks remain solid at depth?
- despite the fact that as temperature rises with depth, rocks reach temperatures that would cause them to melt if they were at the surface, the rocks remain solid at depth because of the extreme pressure acting upon them
- however they do become plastic, subjected to vast amounts of time, such rocks will flow
Give an example of solid creep
- Substances like plasticine will flow under gravity, especially when warm
- In the upper mantle, peridotite (a type of rock) will also display the property of solid creep, this occurs when peridotite reaches 1300 degrees and gives rise to a layer called the athenosphere where the rock is weaker than both overlying and underlying mantle
Describe how rocks ‘behave mechanically as one’ and compromise the lithosphere
The rocks above the asthenosphere, being the uppermost mantle plus the overlying crust behave mechanically as one and compromise what geologists call ‘the lithosphere’. The lithosphere moves as one over the weaker, plastic asthenosphere
What are the 4 pieces of evidence that continents were once joined
- ) Continental fit
- )Biological evidence
- )Geological evidence
- )Climatological evidence
Evidence that the continents were once joined: describe continental fit
- Alfred Wegener noticed a fit between the coasts of South America and Africa
- Continents look like they could be part of a giant ‘Jigsaw puzzle’
Evidence that the continents were once joined: describe the biological evidence
- Wegener also noticed that there was a link between fossil types either side of the Atlantic
- Fossil branchiopods found in Indian limestone are comparable with similar fossils in Australia
Evidence that the continents were once joined: describe the geological evidence
- same rock patterns found in South America, India, Africa, Antarctica and Australia
- rock sequences in Scotland similar to this in Eastern Canada
- many minerals and natural resources also matched and similar striations on rocks in Brazil and West Africa
Evidence that the continents were once joined: ancient climates
- tropical plant remains (coal deposits) found in Antarctica
- glaciation in Africa, South America, India and Australia during the same time (290 million years ago)
What are hot spots
- A concentration of radioactive elements below the crust causes a hot spot to develop
- From this a plume of magma rises to eat into the plate above
- when the lava breaks through to the surface, active volcanoes form above the spot
- the basaltic lava flows slowly and forms huge flattish volcanoes, sometimes referred to as ‘shield’ volcanoes
What is the hottest part of earths surface?
- the equator
- because it receives intense solar radiation
What is global, atmospheric circulation?
- the atmosphere is a highly complex swirling mass of gases, liquids and solids
- these include water droplets, water vapour, ash, carbon dioxide and oxygen
How does global, atmospheric circulation work?
- air that is sinking towards the ground surface forms areas of high pressure (e.g North Pole). Aims on the ground move outwards from these areas
- air that is rising from the ground surface forms areas of low pressure on the ground, for example the equator. Wind from the ground move towards these areas of low pressure
- winds on the ground are distorted by the earths rotation. They curve as they move from areas of high pressure to areas of low pressure
- surface winds are very important in transferring moisture from one place to another
- The patterns of pressure belts and winds are affected by seasonal changes. The seasonal changes cause pressure belts and winds to move north during our summer and south during our winter
What is capacity?
Resources, means and strengths which exist in households and communities that enable them to cope with, withstand, prepare for, prevent, mitigate and/or quickly recover from a disaster
What is community preparedness/risk sharing?
Prearranged measures that aim to reduce the loss of life and property damage through; public education and awareness programmes, evacuation procedures, the provision of emergency medical, food and shelter supplies and the taking out of insurance
What is frequency
The distribution of hazards through time
What is integrated risk management?
The process of considering the social, economic and political factors, involved in risk analysis, determining the acceptability of damage/disruption and deciding on the actions to be taken to minimise this damage/destruction
What is magnitude?
The assessment of the size of the impact of a hazard event
What is mitigation?
Any sustained action taken to reduce or eliminate the risk to life/property
What is monitoring?
The observations and measurements associated with natural evens. Undertaken via specialist data gathering and communication systems, geological exploration, site visits and collaborative studies of current and historical events
What is reconstruction?
The resettlement or relocation of people and ongoing development activities centred on improving not only the built environment and the infrastructure networks but economic and social systems too
What is rehabilitation?
The process of helping communities and individuals to achieve the highest levels of function, cohesion and all round recovery as possible. Actual process will be place-specific but often includes a combination of relief, reconstruction and integrated risk management.
What is relief?
Refers to the process of responding to a hazard/ disaster by providing aid to individuals and communities who have suffered some type of loss. This ‘aid’ can be varied and focusses on dealing with risks as well as preparing, supporting and rebuilding communities. Relief can last from a few hours to several weeks
What is resilience?
The sustained ability of individuals or communities to be able to utilise available resources to respond to, withstand and recover from the effects of natural hazard events
What is mohorivic discontinuity?
Starp divide forming the boundary between the upper mantle and the crust
What is the athenosphere ?
Lies beneath the lithosphere and is semi-molten on which which the plates float and move
What is the lithosphere?
Crust and rigid upper section of the mantle, it is the section of the earth that is divided into the plates
How thick is the lithosphere
approximately 80-100km thick
What does primordial mean?
heat left over from the initial collision of rocks/objects in space during the formation of the earth
What does radiogenic mean?
heat produced by the radioactive decay of isotopes (particularly uranium -238, Thorium -232 ad potassium -40), this material was delivered via the collisions
What are the problems with Wegener’s theory?
- no mechanism for movement of continents
- wind and currents could possibly move continents
What is oceanic crust made up of?
Basalt, silicon, magnesium and oxygen
What is continental crust made up of
Granite, silicon, aluminium, and oxygen
Compare oceanic and continental crust
Oceanic -more dense (3.0g/cc) -young (under 2m years) -thin (0-10km thick) -flat ocean plains, trenches and mountains Continental -less dense (2.7g/cc) -older (over 1,500m years) -thick (20-70km)
What is basaltic magma like?
- low in silica (below 55%)
- gases easily escape, lava is fluid and very hot and flows for long distances before cooling. Only lava is ejected
- lava has not mixed with other materials through subduction, comes directly from mantle at hot spot or spreading ridge
- Hawaii or Iceland-forms shield volcanoes (2-20 degree slopes) or lava plateau’s
- Frequent or regular plateaus
What percentage of basaltic magma is silica?
below 55%
What degree slopes do shield volcanoes have?
2-20 degree slopes
What is acidic lava like?
- either rhyolite or andesite type of lava, high in silica (55-70%)
- andesitic (intermediate) lavas are typical of destructive margins
- rhyolitic (acid) lavas are found at destructive and collision margins
- gasses are trapped, they are viscous and sticky and explosive, can shatter into bombs and shards or to ashes and dust
- magma comes through subduction zone (at destructive boundaries)
- non-frequent eruptions, forms composite stratovolcanoes or acid domes (steep sides)
What percentage of acidic lava is made up of silica?
55-70%
What 5 pieces of supporting evidence are there for plate tectonic theory
- ) Convection currents
- )Paleomagnetism
- )Sea floor spreading
- )Distribution of earthquakes
- )Thickness and age of ocean basin sediments
What process happens at constructive margins?
plates diverge-move away from each other
What geographical features are found at constructive plate margins?
- new oceanic crust is formed by by basaltic magma rising from the athenosphere
- new basaltic rocks
- mid-ocean ridges broken up by transform faults (mid-atlantic ridge)
- shallow-focus earthquakes
- basic volcanoes (eyjafjallajokull)
- volcanic islands
- continental rift valleys (the great African Rift Valley)
What process happens at destructive margins
Plates converge-move towards each other
What geographical features are found at destructive margins?
- oceanic crust is destroyed by subduction and melting at depth
- deep ocean trenches (Mariana Trench)
- Island arcs (West Indies)
- shallow, intermediate and deep focus earthquakes
- explosive, acid volcanoes (Krakatoa)
- oceanic v continental
- continental v continental
Destructive margins: what happens when oceanic plates and continental plates collide?
- oceanic crust is destroyed by subduction and melting at depth
- deep ocean trenches formed (e.g Perth-Chile trench)
- continental land mass is uplifted, compressed and buckled into fold mountains (e.g Andes)
- intermediate and deep focus earthquakes formed, they are explosive, acid volcanoes
Destructive margins: what happens when two continental plates collide?
- colliding plates, and any sediments between them, uplift and concertina into particularly high fold mountains (Himalayas)
- shallow-focus earthquakes
- continued compression and overflowing can result in fracture creating thrust fault and nappe
What process happens at conservative margins?
Plates move sideways past each other
What geographical features occur at conservative margins?
-shallow focus earthquakes (Haiti)
