Geography Reference
In-Depth Information
seismic intensity distribution maps as a basis for
his Californian scenarios. At the widest scale,
earthquake hazards reduction depends on
planning at the international level, under the aegis
of the International Decade for Natural Disaster
Reduction (Bolt 1991). However, seismic
planning does not always involve a rational and
concerted response to objective risk: Berke
et al
.
(1989) surveyed communities in the United States
to find out whether they adopted earthquake
protection measures, or not. They found that the
planning process, rather than the community
context, tended to determine whether mitigation
would occur. Often the measures were chosen as
part of other needs, and hazard mitigation was a
secondary consideration.
Social scientists have devoted considerable
attention to the political and economic aspects
of earthquake hazards. General surveys by Petak
and Atkisson (1982) and Alesch and Petak (1986)
have clarified the situation in California,
especially with respect to the question of how
building codes are updated and enforced. It is
axiomatic that the major advances in seismic
safety follow the principal events that cause
damage or highlight risk. Thus, the 1933 Long
Beach earthquake led to the first serious attempts
to pass and apply anti-seismic building codes in
California (it damaged unreinforced masonry
buildings very substantially, including schools,
where there would have been a considerable
death toll if the earthquake had occurred at a
different time of day). Also, the near failure of the
Lower San Fernando Dam in the earthquake of
1971 (magnitude 6.7), in which liquefaction
lowered the crest by 9 metres, led to new rules
for dam inspection and certification and a new
interest in engineering risk analysis. As a practical
result, the Los Angeles Dam was built to
withstand forces three times as large as those that
its predecessor, the San Fernando Dam, was
designed for. In the 1994 Northridge earthquake
the older dam, which had been retained as a
back-up, was again badly affected, while the new
barrage was not seriously damaged (USGS 1996).
Increasing interest in the economics of
earthquakes has led to some overall studies that
outline the inverse multiplier effects and the
taxation burdens associated with a major seismic
disaster (e.g. US NRC 1992). Losses are rising
considerably, and hence there is also considerable
interest in techniques of loss estimation. The
Hanshin earthquake of January 1995 at Kobe in
Japan is estimated to have cost an order of
magnitude more than the 1989 Loma Prieta
(California) event (US$131.5 billion against
US$12 billion). However, at least part of the
increase may be the result of improved accounting
procedures that take more heed of the hidden
costs than was previously the case. Nevertheless,
much soul searching is now going on regarding
how to pay for the losses. Only a minor part is
likely to be covered by indemnities, but the
burden on the insurance and reinsurance
industries is becoming difficult to bear. There is
thus considerable debate over the best strategy for
sustainable earthquake insurance (Mittler 1990),
although the question of whether individual
householders are motivated to purchase it is a
complex one that involves work on both hazard
perception and economics. In this context, Palm
(1995) found that, although the purchase of
insurance by California households has risen
substantially and now exceeds 50 per cent in some
counties, the pattern of adoption is more related
to the perception of risk than it is to the actual
severity of the hazard.
According to Ohta and Ohashi (1985), the
main factors that govern people's immediate
response to earthquakes are seismic intensity,
spatial conditions, family or other group
composition, age and sex. However, behaviour is
also intimately linked to hazard perception.
Generally, this is less acute and behaviour less self-
protective among poor, disadvantaged and
minority groups (Bolin 1990), although it has also
been linked to personality factors (Simpson-
Housley and Bradshaw 1978). In the heat of the
moment, perception can be seriously wrong and
hence give rise to maladaptive behaviour, which
in extreme cases may lead to injury that otherwise
could have been avoided (Alexander 1990).
Perhaps one of the most contentious social
issues is that of public reaction to earthquake
