Geoscience Reference
In-Depth Information
Introduction to
Natural Hazards
CHAPTER 1
events that appear over a short time period. They
include phenomena such as earthquakes, tsunami,
volcanic eruptions and flash
floods
. This topic deals
mainly with episodic hazards, events that wreak havoc
upon humans. However, the message is not one of total
doom and gloom. Humans choose hazardous areas
because they often offer benefits. For example, ash
from volcanoes produces rich soils that can grow three
crops per year in the tropics, and
floodplains
provide
easily cultivated agricultural land close to a water
supply. Humans in these environments are forced to
predict and avoid natural calamities such as landslides,
cyclones, earthquakes, and drought. Or as Middleton
(1995) states, 'a hazard should be seen as an occasion-
ally disadvantageous aspect of a phenomenon, which
is often beneficial to human activity over a different
timescale.' For those hazards that cannot be avoided
by humans, this topic also examines how people
can minimize their effects and rectify their negative
consequences.
The topic is organized around climatic and geologi-
cal hazards. Intense storms and winds, oceanographic
factors such as waves, ice and sea level changes,
together with extreme precipitation phenomena, are
all investigated under the heading of climatic hazards.
Earthquakes, volcanoes, and land instability are
examined under the topic of geological hazards. This
topic is not concerned overly with biological hazards
such as plague, disease, and insect infestations; but one
RATIONALE
The field of environmental studies is usually intro-
duced to students as one of two themes. The first
examines human effects upon the Earth's environ-
ment, and is concerned ultimately with the question of
whether or not people can irreversibly alter that envi-
ronment. Such studies include the effect of human
impact on climate, of land-use practices on the land-
scape in prehistoric and recent times, and of nuclear
war upon the Earth's environment. The second theme
totally disregards this question of human impact on the
environment. It assumes that people are specks of dust
moving through time subject to the whims of nature.
In this sense, calamities are 'acts of God', events that
make the headlines on the evening news, events you
might wish on your worst enemy but would never want
to witness yourself.
University and college courses dealing with this latter
theme usually treat people as living within a hostile
environment over which they have little control. Such
courses go by the name of '“Natural” Hazards'. The dif-
ference between the two themes is aptly summarized
by Sidle et al
.
(2003). Both themes describe hazards.
The first theme can be categorized as chronic while the
second is episodic or periodic. Chronic hazards would
include desertification, soil
degradation
, and melting of
permafrost. The causes could be due to humans or
global warming. Periodic hazards are large magnitude
