Evacuation versus shelter in place

Evacuation has long been the protective action urged by authorities upon residents threatened by an environmental hazard event. More recently, sheltering in place has been proposed to be more appropriate for particular hazards under some circumstances. In this chapter, we examine evacuation versus shelter-in-place issues in relation to each of eight major weather-related and geophysical hazards. Our starting point is a frequently cited rule of thumb that, in relation to a specific hazard threat, the appropriate protective action response by threatened residents depends on shelter option viability compared with the likely success of evacuation. We clarify use of the terms ‘evacuation’ and ‘shelter’, describe major determinants of the appropriateness of the two protective action options, and summarise the processes involved in effective threat warnings. We discuss evacuation versus shelter-in-place issues in relation to surviving floods, tornadoes, tropical cyclones, wildfires, earthquakes, landslides, tsunamis and volcanic eruptions. We conclude that, in principle, authorities should emphasise the importance of timely evacuation. However, because safe evacuation under imminent threat will not always be possible, authorities should inform residents of the issues involved in sheltering in place safely through consultative engagement with at-risk communities.