Hazards
Hazards in geographical context
What is a hazard?
The threat of substantial loss of life, impact on life or damage to property
caused by an event. Human actions or natural - can be a consequence of
human actions.
Death rate has fallen but more people affected due to population increase.
Loss of property is rising + loss of life is increasing among poor nations.
A disaster is a result of a hazard.
What are the potential impacts of natural hazards?
Impacts depend on e.g. location relative to population + magnitude. Each
hazard has factors that affect the impacts e.g. type + explosivity of a
volcano or vegetation to fuel wildfires.
Each hazard has different driving forces, but some overlap. 3 main types:
● Geophysical - driven by Earth’s internal energy sources
● Atmospheric - driven by processes in the atmosphere
● Hydrological - driven by water bodies, mainly oceans
Perception of hazards
Determined by the effects on our lives. This increases if direct experience
+ extent of long term impact.
The presence of people makes a natural event a hazard. Increasing
populations + demand for land - building in areas at risk.
Advantages
● Fertile soils
● Volcanoes are unlikely to erupt
Natural disaster damage an economy, internally + globally. HICs recover
faster, LICs rely on aid.
Many underestimate hazards. Age, social status + religious beliefs can
determine an evacuation.
Human responses
Natural human responses is to reduce risk of life + equity.
,Locally: saving possessions + safeguarding property
Globally: rescue + aid.
Intensity, magnitude + state of infrastructure affects the speed of
response.
Response times have been reduced by ADAM - accesses info on scale,
supplies + local infrastructure.
Fatalism
Accepting hazards are natural events that we can do little to control.
Interference can impact ecosystems.
Fires are hazardous but also a natural regenerative process + should be
allowed in certain circumstances.
Prediction
Technology has enabled remote sensing + seismic monitoring - shows
activity that may lead to a disaster. Advances in communications allows
info to be shared + analysed quickly. Warnings are prompt + reach a
greater number at risk.
Adaptation
Once we accept that natural events are inevitable, we can adapt so losses
are kept to a minimum - effective + cost-effective for governments.
The hazardous management cycle
A cycle that manages the pre/post-event situations:
Preparedness
● Prevention is rare, but education + awareness can minimise impacts
● Knowing what to do in the aftermath can speed up recovery
● Areas of high risk are more prepared
Response
● Speed depends on the emergency plan
● Immediate responses focus on saving lives
● Damage assessment helps plan recovery
Recovery
● Restoring the area to normality
● Short term: restoration of services
● Longer term: reconstruction
Mitigation
● Actions aimed at reducing the severity of an event + lessening its
impacts
● Direct intervention e.g. earthquake proof buildings
● Long term protection of natural barriers is essential e.g. coral reefs.
● Aid + insurance can reduce the long term impacts, but may not be
, ●
available in high-risk areas or LICs.
The Park model of human response to hazards
A hazard can disrupt everyday life. The type of disruption depends on e.g.
the type of hazard, magnitude + infrastructure. The Park model describes
3 phases - relief, rehabilitation and reconstruction.
Relief
● Immediate local + global response of aid, expertise, search + rescue.
Rehabilitation
● Weeks or months, infrastructure + services are restored to allow
reconstruction to begin.
Reconstruction
● Restoring to the same, or better, quality of life. Measures to mitigate
against a similar event.
, The steepness + depth of the curve indicates the nature + magnitude of
the event e.g. a tsunami would be steep.
The structure of the Earth
Earth structure and internal energy sources
Plato considered the Earth’s structure 2000 years ago. In 1692, Edmond
Halley proposed a theory that it was made up of hollow spheres.
The Earth’s shape is a geoid that bulges around the equator + flatter at
poles. The cause is centrifugal forces, generated by the Earth’s rotation,
which fling the semi-molten interior outwards.
The crust
The Earth’s outer shell - 5 to 10km under oceans - 70km under continents.
It’s thickness relative to the earth is thin.
2 types of crust:
Oceanic
● Broken layer of basaltic rocks: sima (silica + magnesium)
Continental
● Bodies of mainly granitic rocks: sial (silica + aluminium)
Sial - upper layer of crust and forms the continental land masses.
Sima - lower layer of crust, beneath oceans + grading into the lower part
of the sial beneath continents.
Sial is thicker but less dense.
The lithosphere
Together, the crust + the upper mantle. Tectonic plates are formed in this
zone
Hazards in geographical context
What is a hazard?
The threat of substantial loss of life, impact on life or damage to property
caused by an event. Human actions or natural - can be a consequence of
human actions.
Death rate has fallen but more people affected due to population increase.
Loss of property is rising + loss of life is increasing among poor nations.
A disaster is a result of a hazard.
What are the potential impacts of natural hazards?
Impacts depend on e.g. location relative to population + magnitude. Each
hazard has factors that affect the impacts e.g. type + explosivity of a
volcano or vegetation to fuel wildfires.
Each hazard has different driving forces, but some overlap. 3 main types:
● Geophysical - driven by Earth’s internal energy sources
● Atmospheric - driven by processes in the atmosphere
● Hydrological - driven by water bodies, mainly oceans
Perception of hazards
Determined by the effects on our lives. This increases if direct experience
+ extent of long term impact.
The presence of people makes a natural event a hazard. Increasing
populations + demand for land - building in areas at risk.
Advantages
● Fertile soils
● Volcanoes are unlikely to erupt
Natural disaster damage an economy, internally + globally. HICs recover
faster, LICs rely on aid.
Many underestimate hazards. Age, social status + religious beliefs can
determine an evacuation.
Human responses
Natural human responses is to reduce risk of life + equity.
,Locally: saving possessions + safeguarding property
Globally: rescue + aid.
Intensity, magnitude + state of infrastructure affects the speed of
response.
Response times have been reduced by ADAM - accesses info on scale,
supplies + local infrastructure.
Fatalism
Accepting hazards are natural events that we can do little to control.
Interference can impact ecosystems.
Fires are hazardous but also a natural regenerative process + should be
allowed in certain circumstances.
Prediction
Technology has enabled remote sensing + seismic monitoring - shows
activity that may lead to a disaster. Advances in communications allows
info to be shared + analysed quickly. Warnings are prompt + reach a
greater number at risk.
Adaptation
Once we accept that natural events are inevitable, we can adapt so losses
are kept to a minimum - effective + cost-effective for governments.
The hazardous management cycle
A cycle that manages the pre/post-event situations:
Preparedness
● Prevention is rare, but education + awareness can minimise impacts
● Knowing what to do in the aftermath can speed up recovery
● Areas of high risk are more prepared
Response
● Speed depends on the emergency plan
● Immediate responses focus on saving lives
● Damage assessment helps plan recovery
Recovery
● Restoring the area to normality
● Short term: restoration of services
● Longer term: reconstruction
Mitigation
● Actions aimed at reducing the severity of an event + lessening its
impacts
● Direct intervention e.g. earthquake proof buildings
● Long term protection of natural barriers is essential e.g. coral reefs.
● Aid + insurance can reduce the long term impacts, but may not be
, ●
available in high-risk areas or LICs.
The Park model of human response to hazards
A hazard can disrupt everyday life. The type of disruption depends on e.g.
the type of hazard, magnitude + infrastructure. The Park model describes
3 phases - relief, rehabilitation and reconstruction.
Relief
● Immediate local + global response of aid, expertise, search + rescue.
Rehabilitation
● Weeks or months, infrastructure + services are restored to allow
reconstruction to begin.
Reconstruction
● Restoring to the same, or better, quality of life. Measures to mitigate
against a similar event.
, The steepness + depth of the curve indicates the nature + magnitude of
the event e.g. a tsunami would be steep.
The structure of the Earth
Earth structure and internal energy sources
Plato considered the Earth’s structure 2000 years ago. In 1692, Edmond
Halley proposed a theory that it was made up of hollow spheres.
The Earth’s shape is a geoid that bulges around the equator + flatter at
poles. The cause is centrifugal forces, generated by the Earth’s rotation,
which fling the semi-molten interior outwards.
The crust
The Earth’s outer shell - 5 to 10km under oceans - 70km under continents.
It’s thickness relative to the earth is thin.
2 types of crust:
Oceanic
● Broken layer of basaltic rocks: sima (silica + magnesium)
Continental
● Bodies of mainly granitic rocks: sial (silica + aluminium)
Sial - upper layer of crust and forms the continental land masses.
Sima - lower layer of crust, beneath oceans + grading into the lower part
of the sial beneath continents.
Sial is thicker but less dense.
The lithosphere
Together, the crust + the upper mantle. Tectonic plates are formed in this
zone
