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<br />nomic effects of various hazard reduction mea-
<br />sures j
<br />~ development of guidelines for ensuring that
<br />the effects of hazard reduction programs on the
<br />community are shared equitably;
<br />~ a comparative study of the relationship be-
<br />tween hazard reduction measures and major
<br />community values in diverse cultural settings;
<br />~ a comparative study of the political processes
<br />affecting the success of hazard reduction pro-
<br />grams and development of suggestions for effec-
<br />tively dealing with these processes;
<br />. selective study of situations in which tradi-
<br />tional practices and cultural meanings impede
<br />potentially beneficial hazard reduction programs;
<br />. development and dissemination of guidelines
<br />for disaster information programs and for release
<br />of hazard warnings based on study of conditions
<br />leading to public misunderstanding, mass panic,
<br />false-alarm disillusionment, and other coun-
<br />terproductive responses;
<br />~ development of guidelines for promoting
<br />community involvement, motivating organiza-
<br />tional and individual participation, and sustain-
<br />ing interest and activity in hazard reduction
<br />programs; and
<br />~ development of manuals for achieving effec-
<br />tive coordination among organizations involved
<br />in hazard reduction and disaster response.
<br />
<br />INTERACTION OF MULTIPLE
<br />HAZARDS
<br />
<br />Natural hazards often take place as multiple
<br />processes in which an initial hazard triggers
<br />secondary events. For example, an earthquake
<br />may trigger a submarine landslide, which in turn
<br />may cause a tsunami, with devastating effects. Or
<br />two or more hazards, although not directly related
<br />to each other, may occur at the same time in the
<br />same or adjacent localities, triggered by a com-
<br />mon cause. For example, heavy precipitation may
<br />induce debris flows or mudflows along hills lopes
<br />at the same time that flooding occurs in adjacent
<br />river valleys. As mentioned earlier, several exam-
<br />ples of such interrelated multiple hazard events
<br />stand out: the 1964 Prince William Sound,
<br />Alaska, earthquake (magnitude 8.4), which trig-
<br />gered tsunamis, local flooding, and many land-
<br />slides; the killer cyclones in Bangladesh in 1970
<br />and 1985, when wind and flood hazards com-
<br />
<br />bined to kill at least 300,000 and leave 1.3 million
<br />homeless; the 1980 eruption of Mount St. Helens
<br />in Washington, which occurred in association
<br />with earthquake activity, wildfire that consumed
<br />large tracts of timber, and rock-slide failure of the
<br />northern side of the volcano's cone, which in turn
<br />precipitated debris flows and floods up to 100
<br />kilometers downstream; the 1986 Ecuadoran
<br />earthquake, which caused landslides and flooding
<br />due to the formation and breaching of natural
<br />dams; and the 1923 Tokyo earthquake, which
<br />caused a disastrous fire, killing 40,000.
<br />Typically, natural hazard mitigation is under-
<br />taken on the basis of individual hazards. There are
<br />earthquake damage reduction programs, flood
<br />control programs, landslide stabilization pro-
<br />grams, and other such programs. Though they
<br />possess many common features, they also have
<br />unique elements that may not be applicable to
<br />more than one kind of hazard. In addition, the
<br />same mitigative or response action may be gener-
<br />ally applicable to different types of hazards, but
<br />may not be identical for each hazard. For instance,
<br />an evacuation plan may be appropriate for a
<br />number of different hazards, but routes may have
<br />to be modified to avoid low elevations during
<br />floods and hillsides during landslides. Building
<br />code requirements may deal with floods, earth-
<br />quakes, landslides, and tornadoes, but the ideal
<br />requirement for structural walls may be different
<br />for each hazard. For example, a building elevated
<br />to avoid floods may be at greater risk from
<br />earthquake hazards.
<br />Multiple-hazard mitigation can and should be
<br />viewed as a logical and necessary mechanism for
<br />overcoming the limitations of existing single-
<br />hazard mitigation programs. Hazard-interaction
<br />problems require a shift of perspective from the
<br />incrementalism of separate hazards to a broader
<br />systems framework. Increasingly, scientists, engi-
<br />neers, land use planners, and public officials are
<br />recognizing the existence of interactive hazards
<br />that may occur simultaneously or in sequence and
<br />may produce synergistic, cumulative impacts that
<br />are different from those of their separately acting
<br />component hazards.
<br />
<br />LONG-TERM NATURAL HAZARDS
<br />
<br />A group of important natural hazards can be
<br />distinguished from those described above because
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