These notes provided a detailed insight into the topic of Hazards. This is perfect for an AQA Geography A Level student. This file breaks down the content in order for it to be fully absorbed. It finds the perfect balance between bullet points, images, graphs, tables and in depth paragraphs.
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
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