Evacuation, Types of

Three Main Types of Evacuation

While there are some differences between scholars, evacuation is often conceptualized into three major domains, or types, that are not mutually exclusive or collectively exhaustive. The term vertical evacuation refers to a social process where agents relocate from one threatened area to an upper area or areas of the same physical structure. Vertical evacuation is a process dependent upon the scope of the threat, and is common in rising water hazards such as floods, hurricanes, and tsunamis. However, the evacuation process may occur whether or not a threat impacts agents. Depending upon the scope of the exception, vertical evacuation may offer some advantages over other forms of evacuation, as it may dramatically reduce the likelihood of agents trapped between their area of origin and their intended evacuation location. If possible, it is recommended [Page 187]that vertical evacuations accompany some form of preparation, rather than become an evacuation process of last resort. Vertical evacuation should rarely, if ever, be viewed as an appropriate form of evacuation if safer and more accessible forms are available. Horizontal, or site evacuation, refers to a social process where agents relocate from one area threatened by exceptional social disruption to an area or structure that is perceived as less threatening.

Horizontal evacuation is the most common type of evacuation, and frequently involves an attempt to shelter in private or public areas. Not all agents who begin the evacuation process may complete the process to their intended destination. Nonetheless, some scholars, such as Enrico Quarantelli, Kathleen Tierney, Michael Lindell, and Ronald Perry have sought to focus on the evacuation site as an important consideration for understanding the overall context of the evacuation process. During and following a threat, agents may evacuate to an emergency shelter, which is different from a temporary shelter. Emergency shelters, or shelters of last resort or refuge, are intended to provide structurally safe areas for very short periods of time, generally less than 24 hours, to survive the exceptional threat. Temporary shelters provide evacuation facilities for agents, generally for a few hours to less than three weeks, to those whose original area or structure is under greater perceived threat from the exception. A horizontal evacuation may take place whether or not agents are completely out of the danger of the exception. For this reason, attention should focus on reducing the likelihood of exposure to the threat, rather than focusing on the elimination of threat exposure for all agents.

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