Geography Reference
In-Depth Information
5
Earthquakes and vulcanism
David Alexander
architects, geologists and sociologists have also
been highly active in this field.
Nevertheless, small numbers of both physical
and human geographers have studied the effects
of seismicity and eruptions. In this context, the
old aphorism is of little use: geography is not
merely what geographers do, it is also what the
practitioners of other fields accomplish, overtly or
unwittingly, with respect to space and place. Thus,
geophysicists and engineering geologists have
made good use of cartographic methods for both
microzonation, the determination of hazard and
risk at the local scale, and macrozonation, the
plotting of regional damage distributions and
hazard levels. Remote sensing has been used by
vulcanologists to investigate igneous landscapes
and by geologists to elucidate the surface
morphology of active faults. Economists have
studied earthquake hazards as regional inverse
multipliers, and sociologists have looked at the
spatial differentiation of perception and
organisational behaviour. Geographers have
distinguished themselves with studies of volcanic
and seismic landforms, earthquake insurance,
regional patterns of post-disaster reconstruction,
and hazard and risk perception and zonation.
This chapter will focus on applied geographical
work on seismic and volcanic hazards regardless of
whether it has been carried out by geographers or
not, although their work will be highlighted
where appropriate. Relevant studies are those that
deal significantly with practical problems of
landscape, location or the spatial dimension in
general, even in the context of other factors such
INTRODUCTION
On average, twenty-seven earthquakes and four or
five volcanic eruptions cause disasters each year.
The earthquakes kill about 19,000 people and
injure 26,000, while the eruptions kill 1000 and
injure fewer than 300. These figures represent less
than 10 per cent of natural hazard mortality,
although nearly 50 per cent of morbidity; and
although more than 2 million people are directly
affected each year in some way by earthquakes and
volcanic eruptions, they are only 1.5 per cent of
all people who suffer the effects of natural
catastrophe, as many more are affected by floods
and droughts (IFRCRCS1997).
Earthquakes and vulcanism are a subset of the
general interdisciplinary field of natural hazards.
The approach to these varies from geophysical
to social and psychological. Between these end
members there is a broad spectrum that includes
studies of hazard, vulnerability, risk, perception,
economic conditions, historical aspects, remote
sensing, cartography, and the technical aspects of
monitoring and warning. Since they were first
conceived, natural hazard studies have
maintained a strong applied dimension, sustained
by the need to make the environment of life safe
against extreme natural events and thus to reduce
the toll of casualties and damage.
The role of geographers in studying
earthquakes and vulcanism has been secondary to
that of many other types of scientist and scholar.
Many advances have come from seismologists,
vulcanologists and other geophysicists. Engineers,
