ABSTRACT
In theory, the safest response to environmental hazard is to avoid all danger. In practice, this is impossible, largely due to the development pressure on land. Even after severe disasters, inertia and the remaining infrastructure encourage rebuilding on the same – or a nearby – site. A few small island communities overwhelmed by disaster have been moved long distances but the relocation may not be permanent. Within two years of evacuation to Britain following a volcanic eruption in 1961, most of the population of Tristan da Cunha, South Atlantic, had returned home. Another largely theoretical response is the suppression of hazards at source. Humans can exert little influence on natural processes like those that, in a single day, deliver to the atmosphere enough solar energy to generate 10 thousand hurricanes, 100 million thunderstorms or 100 billion tornadoes. Expressed relative to this energy receipt (i.e. taking the daily global solar energy receipt as 1 unit), a very strong earthquake would release 10-2 units; an average cyclone 10-3 units (Fig. 4.1). Where attempts have been made to suppress hazards at source, for example by cloud seeding, there is concern about the possible adverse environmental and ecological consequences.
