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Classifying Natural
Disasters
Comparing and Analyzing Natural
Disasters
What is a natural hazard or
disaster?
Aspects of the physical world that
have the potential to cause
considerable harm to people.
 Caused by natural forces rather
than by human action
 Can you think of any examples?

What is a natural hazard or
disaster?
The international Red Cross estimates
that on average over the past 25
years 138,000 people have been
killed, 46,000 injured and more than 4
million left homeless each year by
natural disasters
 These figures do not include the
recent tsunami in Asia (273,000) and
Hurricane Katrina (1000)

What is a natural hazard or
disaster?

Natural disasters often occur in those
areas of the world which are heavily
populated
Classifying Natural Disasters

Most common way of comparing
natural disasters is to measure their
impact by the loss of life, the
number of injuries and the damage
to property that these events cause
Classifying Natural Disasters
We can also measure these
disasters by the strength or
intensity of the event (for example
the wind speed of a hurricane)
 In addition, we classify natural
disasters by the impact they have
on human beings, by the regions in
which they occur and their
frequency

Classification System
We can classify natural disasters by
the chief process or sphere in which
it operates
 Using this system of classification
there are three categories

Classification System
Atmospheric Hazards
Cyclonic Storms (hurricane)
Tornado
Severe Storm
Flooding
Drought
Wildfire
Severe Weather (hot/cold)
Classification System
Biological Hazards
Infectious Disease
Parasitic Disease
Insect Infestation
Plant Disease
Classification System
Geological Hazards
Slide (mud, land, rock)
Volcanic Activity
Earthquake
Avalanche
Tsunami (tidal wave)
Comparing and Analyzing
Natural Disasters
Any specific natural disaster can be
described by analyzing various
factors that determine how great an
impact it will have on people
 This system recognizes six main
factors

Comparing and Analyzing
Natural Disasters
1) Frequency- how often is the event
likely to happen
2) Duration- the length of time the
event lasts
3) Extent- does it affect a wide area
or region or a small one
Comparing and Analyzing
Natural Disasters
4) Speed of onset- happen quickly with
no warning and over quickly or build
slowly before the peak period
5) Spatial dispersion- the area that is
likely to be affected by a particular
event
6) Temporal spacing- how hazards and
disasters occur in time; are they
random or do they occur within a
cycle