Geoscience Reference
In-Depth Information
The literary and field studies of ancient and modern earthquakes show that peo-
ple view differently the challenges and hazards of their natural environment. In
historical times the damage and sudden crippling of the economy of a state, had lead
to population movements, emigration, crises in political affairs, triggering invasions
and wars as well as truce between belligerent states. Loss of life should have been
considerable but difficult to estimate.
Also in modern times, particularly in developing countries, earthquakes have
caused economic and political crises, increase in taxation and the undesirable,
though necessary borrowing from other countries.
The average number of people killed annually is certainly less than the annual
number of persons killed today by drugs and motor cars. At the present level of
technology, earthquakes cannot be prevented. However, subject only to budgetary
restraints their disastrous effects can be minimised.
Earthquakes are destructive because man has made them so by investing his
wealth with a disregard for the hazards that Nature may have in store for him. This
disregard stems from a variety of causes. The most important being the mere lack
of awareness and technical knowledge to alleviate such hazards. Another cause is
often the apathy of the populace which is probably due to ignorance. It was, and to
some extent still is not uncommon for people to accept earthquakes and their effects
as Acts of God about which very little can be done.
The difference in attitude to earthquake hazards found in both historical and
modern times cannot be explained in terms of the magnitude or frequency of such
disasters alone. It is the perception of the disaster that controls the attitude and stim-
ulates awareness. For instance, very little improvement in building materials and in
methods of construction results from an earthquake that destroyed or today destroys
remote villages in a developing country. After a very short period of enthusiasm for
restoring plan, the interest of the few concerned dies out. Apart from those inflicted,
few in the country will be affected and soon the whole problem will be forgotten.
In contrast, the damage or destruction of a capital city or of a major engineering
structure on which depends the economy of the country will stimulate a completely
different degree of awareness. Here, the disaster may or may not affect the economy
of the country but the strain will be felt by all.
As we cannot know what will happen in the future, to estimate likely earthquake
hazards we have to find out what happened in the past and extrapolate from there a
little. Previous research has uncovered evidence of destructive earthquakes in areas
where only small events have been experienced recently. This is not surprising: the
timescale of geology is vastly different from that of human history, so some parts
of the world may suffer violent earthquakes over a very short period of the geo-
logical time scale. It follows, therefore, that if we took account only of information
about the last century, in which earthquakes have been recorded by instruments (and
even then not uniformly throughout the globe), we would have no way of knowing
whether an apparently seismically “quiet” area today is in fact at risk from a dam-
aging earthquake.
For the Eastern Mediterranean and the Near East there is a large number of descrip-
tive and parametric, but confusing catalogues of historical earthquakes. Obviously
the value of parametric catalogues will be only as good as the descriptive catalogues.
Search WWH ::
Custom Search