Transcript Hazards Definitions And Characteristics - Geog

Hazards
Definitions And Characteristics
Definitions
• Hazard: A threat (whether natural or human)
that has the potential to cause loss of life,
injury, property damage, socio-economic
disruption, or environmental degradation.
• Hazard Event: The occurrence (realization) of
a hazard, the effects of which change
demographic, economic, and/or
environmental conditions.
Definitions
• Disaster: A major hazard event that causes
widespread disruption to a community or region,
with significant demographic, economic and/or
environmental losses, and which the effected
community is unable to deal with adequately
without outside help.
• Vulnerability: The geographic conditions that
increase the susceptibility of a community to a
hazard or to the impacts of a hazard event.
• Risk: The probability of a hazard event causing
harmful consequences.
Types
Climatic/
Meteorological
Geological/
Geomorphological
Floral
Faunal
Snow and Ice
Avalanches
Fungal Diseases
Bacterial Diseases
Droughts
Earthquakes
Athlete’s Foot
Viral Diseases
Floods
Erosion (Soil and Coastal) Dutch Elm Disease
Influenza
Frosts
Landslides
Wheat Stem Rust
Malaria
Hail
Shifting Sand
Infestations
Smallpox
Heatwaves
Tsunami
Hay Fever
Rabies
Tropical Cyclones
Volcanic Eruptions
Poisonous Plants
Infestations
Lightning and Fires
Rabbits/Termites
Tornadoes
Venomous Bites
What Happens Where? (Some)
Tropical Storms
Earthquakes
Drought
Tornadoes
Active Volcanoes
Mexico
Colombia
Central USA
Japan
Iceland
West Indies
Gulf Of Mexico
N & S Africa
Australia
Antarctica
Kenya
Florida
Brazil
South Africa
Africa
Australia
Argentina
Australia
Gulf Of Mexico
India
China
Peru
Afghanistan
India
Japan
India
Alaska
Germany
New Zealand
Colombia
California
France
Indonesia
San Francisco
Spain
Peru
Los Angeles
Colombia
Turkey
USA
China
Alaska
Indonesia
Characterising Hazards
• Magnitude: The size of the event e.g. Force 10 on the
Beaufort Scale, Maximum Height or Discharge of a Flood,
or the size of an Earthquake on the Richter Scale.
• Frequency: How often an event of a certain size occurs.
For example a flood 1m high may occur, on average,
every year. By contrast in the same stream a flood of 2m
might occur only every 10 years. The frequency is
sometimes called the recurrence interval (Gumbel’s
Laws). The larger the event, the less frequently it occurs.
However it is the very large events that do most of the
damage (to the physical environment, to people,
properties, and livlihoods).
Characterising Hazards
• Duration: The length of time that an environmental
hazard exists. This varies from a matter of hours, such
as with urban smog, to decades, in the case of drought,
for example.
• Areal Extent: The size of the area covered by the
hazard. This can range from very small scale, such as an
avalanche chute, to continental, as in the case of
drought.
• Spatial Concentration/Dispersion: Is the distribution
of hazards over space; whether they are concentrated
in certain areas, such as tectonic plate boundaries,
coastal locations and valleys etc.
Characterising Hazards
• Speed Of Onset: This is rather like the lag-time
in a flood hydrograph. It is the time difference
between the start of the event and the peak of
the event. It varies from rapid events, such as
the Kobe Earthquake, to slow time-scale events
such as drought in the Sahel of Africa.
• Regularity: (or temporal spacing). Some
hazards, such as cyclones, are regular; whereas
others, such as earthquakes and volcanoes, are
much more random.
Activity 1
Look at the “Natural Hazards” Worksheet
and…
1. Try to work out what type of hazard it is.
2. A place in the world it could happen.
3. Whether it is natural or human induced.
Activity 2
Look at the “What Is A Natural Hazard?” Worksheet and
answer the following…
1. What would be your definition of an “Extreme
Natural Event” and why?
2. What is a “Vulnerable Population” and what makes
them vulnerable?
3. Explain the interaction/consequences of the
interaction between an “Extreme Natural Event” and
a “Vulnerable Population”.
4. Is the definition of a Natural Hazard justified? Is there
anything that could be added?