GEOGRAPHY REVISION – PHYSICAL
UNIT TWO: Hazards
What is a hazard?
A hazard is the threat of substantial loss of life, substantial impact upon life or damage to property that can be caused by an
event.
These events can be caused by human actions (explosions/nuclear incidents) or MAINLY natural (earthquakes, volcanoes) &
the natural events can be a consequence of human actions (wildfires)
The Emergency events data base (EM-DAT) suggests a hazard becomes a disaster (a disaster occurs as result of a hazard)
when one of the following are met:
10+ people are killed, 100+ people are effected, A state of emergency is declared, International assistance is called for
Natural hazard: A natural event (Volcanic eruption) that can destroy/severely damage human life and property
Disaster: An event which causes severe damage and destruction to humans, the environment and the economy.
Potential Impact of natural hazards – determined by a number of factors
e.g. Location of hazard relative to areas of population & magnitude and/or extent of hazard
BUT, each hazard also has its own determining factors
e.g. the type and explosive tendancies of a volcano OR availability of vegetation to fuel wild fires
Hazard Categories (some can be fitted into two categories) – e.g. Volcanoes have impacts on atmosphere which effects weather
1. Geophysical – Driven by the earths own internal energy sources (e.g. plate tectonics, volcanoes, seismic activity)
2. Atmospheric – Driven by processes at work in the atmosphere (e,g, tropical storms, droughts)
3. Hydrological – Driven by water bodies, mainly the oceans (e.g. flood, storm surges, tsunamis)
Natural hazards have common characteristics
Their origins are clear & their effects distinctive (e.g. Earthquakes causing buildings to collapse)
Most only allow a short warning time before the event (some hardly at all)
Exposure to the risk is involuntary. (applies to the population of less-developed countries) WHEREAS (well developed
countries are almost always well aware of the risk but choose to ignore or minimise it)
Most losses to life & damage occur shortly after the event. BUT, their effects can last for ages in communities (e.g. disease,
disruption of communications)
Most require an emergency response (as a result of scale and intensity
Potential impacts of hazards
S - Social Primary Impact – Immediate effect on the affected area (destruction of
E - Economic infrastructure/buildings)
E – Environment Secondary Impact – Effects which happen after the disaster has occurred, related to the
P- Political event (disease, contamination of water supplies, economic recession)
Scale – Local, National Global
Positives and negatives:
1. SOCIAL: Health & wellbeing, community, living standards, diseases, psychological impact
2. ECONOMIC: Property damage, loss of jobs, businesses, financial aid to repair
3. ENVIRONMENTAL: Wildlife (flora/fauna), ecosystems, foodchains
4. POLITICAL: government (scale)
Perception of hazards – dependant on the effect it may have on our lives
Vulnerability – the exposure to risk and hazards
The pressure of an increasing population and subsequent demand for land has resulted in building in areas that are at
increased risk
The advantages of living with the threat of hazards sometimes outweighs the risk (e.g. making use of fertile soils on flood
plains can be considered a risk worth taking)
, 1971 – Robert Kates found that of those people who had experiences of storm damage to their property on the east coast of
the USA, over half (majority) did not expect such damage to occur again
Age, social status, cultural beliefs, economic position, and religious beliefs can all be determinant factors.
1. Socio-economic status – Rich: sense of invincibility, access to insurance, wealthy area (good emergency services), ability
to start over, defence mechanisms
Poor: Less money to rebuild following destruction, inability to move (nowhere else to go), more acceptance (fatalistic
approach)
2. Wealth of country (developed/undeveloped) – Disaster itself may be minimised by developed government. Wealth can
determine level of help and recovery. Quicker bounce back.
3. Past Experience – Level of experience corresponds with ability and familiarity with how to deal/bounce back. Unique
event there is no known approach for what to do. Reoccurring incident may have a handled way.
4. Education – Access in order to understand the risk leads to better, more understanding view. How to deal with it is
understood, less fear associated. OR Less educated have little knowledge on its disastrous consequence (ignorance)
5. Personality – Ability to cope with the impending possibility. Fear factor, casual or stressed attitude towards it?
Reponses to hazards
Natural, innate human response is to reduce risk to life and equity.
Local level – this may involve saving possessions and safeguarding property… Global Level – this means coordinating rescue and
humanitarian aid
Speed of international response – affected by the intensity and magnitude of event as well as the original state of the
infrastructure (and how badly it has been damaged)
Response times have been reduced by the ADAM (Automatic Disaster Analysis and Mapping System) a database which pulls
together information from US geological survey, world bank and world food programme. (immediate access to scale of
disaster, what supplies are available)
1. FATALISM – The acceptance that hazards are natural events we can do little to control and losses have to be accepted
2. PREDICTION – As technology increases, the methods of predicting hazardous events becomes more sophisticated (e.g.
remote sensing and seismic monitoring gives clues to activity that may lead to a disaster).
Advances in communications mean that information from all parts of the world can be shared and analysed quickly
3. ADAPTATION – Once we accept that natural events are inevitable, we can adapt our behaviour accordingly so that losses
can be kept to a minimum.
This is the most realistic option for many people and proves to be effective and cost-effective for governments.
Disaster risk equation Hazard – history, magnitude, size, frequency, nature, characteristics
Vulnerability – close proxemics, wealth, experience
RISK = HAZARD X VULNERABILITY Capacity – ability to ‘bounce back’, withstand a hazard, emergency
CAPACITY (TO COPE) services, wealth, evacuation programmes,
The Hazard Management Cycle
1. Preparedness – large scale events can unlikely be prevented, but
education and raising public awareness can adjust behaviour to
minimise the likely impact. Knowing what to do in the immediate
aftermath speeds up recovery process. (level of preparedness will be
higher in high risk areas)
2. Response – Speed of response will depends on effectiveness of
emergency plan put in place. Immediate response focus on saving
lives and coordinating medical assistance. Damage assessment helps
plan for recovery.
3. Recovery - Restoring the affected area to something approaching
normality. Short term – restoration of services so that longer term
planning & reconstruction to the pre-event levels can begin.
4. Mitigation – Actions aimed at reducing severity of event and its
impact. This can be direct intervention (building infrastructure which
can withstand them), or preparing barriers or zones that may slow
down or halt the advance(of wildfire)
, Most desirable is the long term protection of natural barriers (coral reefs) which protect the shore against storm surges.
Support after the event, in the form of aid and insurance, can reduce the long term impacts. (Not available to everyone
though, even in developed countries & not at all to undeveloped countries)
The Park Model – describes the phases following a hazardous event
1. Stage 1: Quality of life is normal before disaster strikes. People
try their best to prepare if such events occur (educating)
2. Stage 2: The Hazardous event
Immediately the quality of life drops, people attempt to use
prevention methods (barricades, evacuation)
3. Stage 3: Relief
Immediate local/ possible global response in the form of aid,
expertise and search and rescue. (hours to days)
4. Stage 4: Rehabilitation
Infrastructure and services are restored, as well as food and
shelter, albeit possibly temporary, to allow the reconstruction
phase to begin ASAP - an attempt to return to normalcy (days
to weeks)
5. Stage 5: Reconstruction
Restoring to the same, or better, quality of life as before the
event took place. Includes measures to mitigate against a
similar level of disruption if the event occurs again (weeks to
years)
The Earth’s Structure
The earth’s interior structure is layered in spherical shells. These
shells can be sub-divided into four major divisions: Inner core, outer
core, mantle & crust.
1. Inner Core:
Core made of two parts, the inner is solid & made of iron-nickel alloy.
Dense ball of metal
Radius of approximately 1200km
Temperature in excess of 6000’c
Core & its internal heat is major cause of activity on earth.. Most
of it thought to have derived from the radioactive decay (of
Uranium, potassium, Thorium) and small amounts retained from
the ball of dust and gas from which the earth evolved
3. Outer Core
Core made of two parts, the outer is semi liquid (as a result of inner core heat) & made of iron and nickel
Temperature 4000-5000’C
Larger radius at 2200km
Spherical movement around the inner core is what generates Earth’s magnetic field
2. Mantle
Made of molten & semi molten rocks
Contains lighter elements such as silicon and oxygen.. Made of silicates of iron and magnesium, sulphites and oxites.
Known as the thickest layer (2900km deep)
Makes up 84% of the Earth’s volume
3000’c on average
UNIT TWO: Hazards
What is a hazard?
A hazard is the threat of substantial loss of life, substantial impact upon life or damage to property that can be caused by an
event.
These events can be caused by human actions (explosions/nuclear incidents) or MAINLY natural (earthquakes, volcanoes) &
the natural events can be a consequence of human actions (wildfires)
The Emergency events data base (EM-DAT) suggests a hazard becomes a disaster (a disaster occurs as result of a hazard)
when one of the following are met:
10+ people are killed, 100+ people are effected, A state of emergency is declared, International assistance is called for
Natural hazard: A natural event (Volcanic eruption) that can destroy/severely damage human life and property
Disaster: An event which causes severe damage and destruction to humans, the environment and the economy.
Potential Impact of natural hazards – determined by a number of factors
e.g. Location of hazard relative to areas of population & magnitude and/or extent of hazard
BUT, each hazard also has its own determining factors
e.g. the type and explosive tendancies of a volcano OR availability of vegetation to fuel wild fires
Hazard Categories (some can be fitted into two categories) – e.g. Volcanoes have impacts on atmosphere which effects weather
1. Geophysical – Driven by the earths own internal energy sources (e.g. plate tectonics, volcanoes, seismic activity)
2. Atmospheric – Driven by processes at work in the atmosphere (e,g, tropical storms, droughts)
3. Hydrological – Driven by water bodies, mainly the oceans (e.g. flood, storm surges, tsunamis)
Natural hazards have common characteristics
Their origins are clear & their effects distinctive (e.g. Earthquakes causing buildings to collapse)
Most only allow a short warning time before the event (some hardly at all)
Exposure to the risk is involuntary. (applies to the population of less-developed countries) WHEREAS (well developed
countries are almost always well aware of the risk but choose to ignore or minimise it)
Most losses to life & damage occur shortly after the event. BUT, their effects can last for ages in communities (e.g. disease,
disruption of communications)
Most require an emergency response (as a result of scale and intensity
Potential impacts of hazards
S - Social Primary Impact – Immediate effect on the affected area (destruction of
E - Economic infrastructure/buildings)
E – Environment Secondary Impact – Effects which happen after the disaster has occurred, related to the
P- Political event (disease, contamination of water supplies, economic recession)
Scale – Local, National Global
Positives and negatives:
1. SOCIAL: Health & wellbeing, community, living standards, diseases, psychological impact
2. ECONOMIC: Property damage, loss of jobs, businesses, financial aid to repair
3. ENVIRONMENTAL: Wildlife (flora/fauna), ecosystems, foodchains
4. POLITICAL: government (scale)
Perception of hazards – dependant on the effect it may have on our lives
Vulnerability – the exposure to risk and hazards
The pressure of an increasing population and subsequent demand for land has resulted in building in areas that are at
increased risk
The advantages of living with the threat of hazards sometimes outweighs the risk (e.g. making use of fertile soils on flood
plains can be considered a risk worth taking)
, 1971 – Robert Kates found that of those people who had experiences of storm damage to their property on the east coast of
the USA, over half (majority) did not expect such damage to occur again
Age, social status, cultural beliefs, economic position, and religious beliefs can all be determinant factors.
1. Socio-economic status – Rich: sense of invincibility, access to insurance, wealthy area (good emergency services), ability
to start over, defence mechanisms
Poor: Less money to rebuild following destruction, inability to move (nowhere else to go), more acceptance (fatalistic
approach)
2. Wealth of country (developed/undeveloped) – Disaster itself may be minimised by developed government. Wealth can
determine level of help and recovery. Quicker bounce back.
3. Past Experience – Level of experience corresponds with ability and familiarity with how to deal/bounce back. Unique
event there is no known approach for what to do. Reoccurring incident may have a handled way.
4. Education – Access in order to understand the risk leads to better, more understanding view. How to deal with it is
understood, less fear associated. OR Less educated have little knowledge on its disastrous consequence (ignorance)
5. Personality – Ability to cope with the impending possibility. Fear factor, casual or stressed attitude towards it?
Reponses to hazards
Natural, innate human response is to reduce risk to life and equity.
Local level – this may involve saving possessions and safeguarding property… Global Level – this means coordinating rescue and
humanitarian aid
Speed of international response – affected by the intensity and magnitude of event as well as the original state of the
infrastructure (and how badly it has been damaged)
Response times have been reduced by the ADAM (Automatic Disaster Analysis and Mapping System) a database which pulls
together information from US geological survey, world bank and world food programme. (immediate access to scale of
disaster, what supplies are available)
1. FATALISM – The acceptance that hazards are natural events we can do little to control and losses have to be accepted
2. PREDICTION – As technology increases, the methods of predicting hazardous events becomes more sophisticated (e.g.
remote sensing and seismic monitoring gives clues to activity that may lead to a disaster).
Advances in communications mean that information from all parts of the world can be shared and analysed quickly
3. ADAPTATION – Once we accept that natural events are inevitable, we can adapt our behaviour accordingly so that losses
can be kept to a minimum.
This is the most realistic option for many people and proves to be effective and cost-effective for governments.
Disaster risk equation Hazard – history, magnitude, size, frequency, nature, characteristics
Vulnerability – close proxemics, wealth, experience
RISK = HAZARD X VULNERABILITY Capacity – ability to ‘bounce back’, withstand a hazard, emergency
CAPACITY (TO COPE) services, wealth, evacuation programmes,
The Hazard Management Cycle
1. Preparedness – large scale events can unlikely be prevented, but
education and raising public awareness can adjust behaviour to
minimise the likely impact. Knowing what to do in the immediate
aftermath speeds up recovery process. (level of preparedness will be
higher in high risk areas)
2. Response – Speed of response will depends on effectiveness of
emergency plan put in place. Immediate response focus on saving
lives and coordinating medical assistance. Damage assessment helps
plan for recovery.
3. Recovery - Restoring the affected area to something approaching
normality. Short term – restoration of services so that longer term
planning & reconstruction to the pre-event levels can begin.
4. Mitigation – Actions aimed at reducing severity of event and its
impact. This can be direct intervention (building infrastructure which
can withstand them), or preparing barriers or zones that may slow
down or halt the advance(of wildfire)
, Most desirable is the long term protection of natural barriers (coral reefs) which protect the shore against storm surges.
Support after the event, in the form of aid and insurance, can reduce the long term impacts. (Not available to everyone
though, even in developed countries & not at all to undeveloped countries)
The Park Model – describes the phases following a hazardous event
1. Stage 1: Quality of life is normal before disaster strikes. People
try their best to prepare if such events occur (educating)
2. Stage 2: The Hazardous event
Immediately the quality of life drops, people attempt to use
prevention methods (barricades, evacuation)
3. Stage 3: Relief
Immediate local/ possible global response in the form of aid,
expertise and search and rescue. (hours to days)
4. Stage 4: Rehabilitation
Infrastructure and services are restored, as well as food and
shelter, albeit possibly temporary, to allow the reconstruction
phase to begin ASAP - an attempt to return to normalcy (days
to weeks)
5. Stage 5: Reconstruction
Restoring to the same, or better, quality of life as before the
event took place. Includes measures to mitigate against a
similar level of disruption if the event occurs again (weeks to
years)
The Earth’s Structure
The earth’s interior structure is layered in spherical shells. These
shells can be sub-divided into four major divisions: Inner core, outer
core, mantle & crust.
1. Inner Core:
Core made of two parts, the inner is solid & made of iron-nickel alloy.
Dense ball of metal
Radius of approximately 1200km
Temperature in excess of 6000’c
Core & its internal heat is major cause of activity on earth.. Most
of it thought to have derived from the radioactive decay (of
Uranium, potassium, Thorium) and small amounts retained from
the ball of dust and gas from which the earth evolved
3. Outer Core
Core made of two parts, the outer is semi liquid (as a result of inner core heat) & made of iron and nickel
Temperature 4000-5000’C
Larger radius at 2200km
Spherical movement around the inner core is what generates Earth’s magnetic field
2. Mantle
Made of molten & semi molten rocks
Contains lighter elements such as silicon and oxygen.. Made of silicates of iron and magnesium, sulphites and oxites.
Known as the thickest layer (2900km deep)
Makes up 84% of the Earth’s volume
3000’c on average
