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What are hazards?
Hazard: Becomes a hazard when a natural event starts to threatens people, by causing life loss or injury,
economic damage or environmental degradation. There are 2 types of natural hazards:
1)Geophysical ­ results from geological/geomorphologic processes. Eearthquakes, volcanoes & slides
2)Hydro-meteorological -Hazard formed by hydrological (floods) & atmospheric (storms) process's.
Includes drought, flooding and tropical storms
Environmental Hazards
Natural hazards ­ caused by Na-Tech hazards ­ natural hazard Techno hazards ­ Nuclear
geophysical/hydro - triggers technological disaster, eg/ power leaks etc.
meteorological process's. flood causing dam to burst
Disasters for vulnerable people
Chronic hazards ­ Climate
Super hazards ­ Earth changes
change and pollution. Increase
Global environmental change from super volcanoes, tsunamis
threat of environmental
etc.
hazards.
Chronic Hazards…read more

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What are disasters?
It's hard to tell precisely when a hazard becomes a disaster D Vulnerable
but dregs model shows the overlap required before a hazard Hazardous I
population:
S
becomes a disaster. It's a matter of scale, a disaster is geophysic- A human and
S economic
bigger than a hazard. Some insurance companies have tried al event. T loss, due to
to define it as a loss of more than 20 loves and an economic E
location.
R
loss of over $16million.
One factor as to whether it has become a disaster or not depends on how vulnerable the
population is.
Vulnerability: High risk combined with an inability of individuals to cope.
Location
Lack of accessibility Low
Poverty capacity
High population density to cope.
Urban migration due to population increase.
Risk: The probability of a hazard event occurring
and creating loss of lives.
Hazards to people (death + disease) Risk = Frequency/Magnitude x level of vulnerability
Hazards to goods (economic loss) Capacity to cope
Hazards to environment (pollution)…read more

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Why do people remain at risk from hazards & disasters?
Changing risks ­ It's difficult to predict where or when an event may occur and
the impact it will have. They vary in space as well as time due to changing human
activities and physical factors such as tectonic plate movement. Places once safe to
live are now in danger due to rising sea levels, deforestation and other changes.
Lack of alternatives ­ Often the most vulnerable people are the poorest and are
forced to live in unsafe places due to lack of knowledge or better alternatives.
Benefits vs costs ­ Benefits include fertile farming land, which may outweigh the
risks from it.
Risk perception ­ People are comforted by statistics which show the risk of death
from a hazard as very low and believe it won't happen in their life time.
An ageing population - Older people (65+) are the least mobile in a community
and have less capacity to take action either before or after a natural disaster.
Dependence on technology - Our belief that we are able to predict and control the
natural environment and its processes has led us to develop areas for human
habitation which previously may not have been considered safe or viable. Also we'
re more dependent on systems of water, power, communication and transport than
ever before. When these systems collapse under the onslaught of a natural hazard,
we are unable to fend for ourselves.…read more

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Global Hazard Trends (how & why are natural hazards an
increasing threat?)
Global disaster trends - Natural disasters are more common in countries with a low and
medium level of development. Many of these countries are in tropical areas which have
monsoon rainfall or hurricanes. Disasters cause more death and disruption in poor
countries, which lack the resources and funds to develop high-tech prevention and
prediction systems. Damage in absolute economic terms remains highest in high-income
countries but in relative terms it is much more devastating for poorer countries.
Interpreting statistics - Reported by governments. Validity is questioned for number of reasons:
1)No universal definition of disaster so therefore it's down to each persons interpretation
2)When reporting deaths, it depends on whether deaths from both primary & secondary disasters
are reported or just primary.
3)Depending on location disasters go unreported.
4)Declaration of deaths may be subject to political influences, perhaps to make money.
5)Complex to collect depending on location and accuracy of existing statistics.
6)Time trend analysis (trends over time) can be difficult depending on the intervals.
Analysis of hazard trends ­ The number of reported statistics has risen significantly in recent
year perhaps due to growing media as well as increasing number of vulnerable people. Since
1960's hydro-meteorological have rising dramatically, geophysical have had no overall rising
and biological slow slight rise from 1990's onwards.…read more

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Magnitude and frequency ­ Magnitude (size of natural hazard. Represents energy given off
during event). Magnitude scales categorise events according to size/energy. Scales include:
Hurricanes: Saffir-Simpson scale (1-5)
Earthquakes: Richer Scale (1-10 log scale)
Tornadoes: TORRO or Fujita intensity scales
Volcanic eruptions: explosivity index
Lower magnitude events, such as an earth tremor of Richter Scale 2.5, have less than high-
magnitude events, such as the 2004 earthquake measuring 9.1 on the Richter Scale.
Frequency (number of events of given magnitude which occur over time). Low magnitude
events are likely to have a more frequency recurrence level, and present more frequent but
less devastating risks.
Contrasting trends - Geophysical hazards show fluctuations over time which can be
accounted for by the clustering of events along mobile plate boundaries. There have been a
number of earthquakes off the coast of Indonesia, where the Indian plate is being subducted
beneath the Burma plate. However, there is no solid evidence that the frequency/magnitude
of hazards is increasing. In contrast number of reported hydro-meteorological events is
increasing, likely to be associated with climate change, with predictions that global warming
will increase frequency, magnitude & impact of the disasters. Another explanation of
increased frequency lies in the context hazard of increased environmental degradation
caused by population pressure such as deforestation leading to flash flooding. We cannot be
sure that damage to environment causes disasters, but it's clear that it impacts on them.…read more

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Comments

Mr A Gibson

40 slides of information which are organised into a good set of facts and figures, causes and effects and case studies. This woudl be really good for your general knowledge around this topic area.

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