Human populations are threatened by a broad spectrum of environmental hazards ranging from natural hazards like floods and wildfires to human-induced threats like train derailments and hazardous materials releases.  In many cases these events result in the need to warn the public to take protective action, which may include evacuating or sheltering-in-place.  The focus of this research project was protective action triggers (or triggers), a common decision aid used by emergency managers to time public warnings in a disaster event (i.e. When should we recommend that citizens take protective action?)  A common example is to set a trigger such that a community will be warned to evacuate if an approaching wildfire crosses a ridgeline.  Triggers can be viewed as having three components: a detectable condition, a recommended protective action, and a threatened target population to warn. 

The primary research objectives and outcomes of this research were to:

1) Improve our understanding of the types of triggers used across a wide range of environmental hazards.  The primary result of this research was a substantial improvement in our scientific knowledge regarding triggers in terms of how they are structured, their unique characteristics, and how they are used across many environmental hazards.  This also yielded a classification scheme that can be used to group triggers based on many factors.  One example of a class of triggers is a “pre-event trigger” that would be used to warn a community to shelter-in-place if a toxic chemical release was automatically detected.

2) Advance our understanding of how triggers are set by decision makers and the key factors that they rely upon.  Our subjects in this research theme were professional wildfire incident commanders (ICs) who ran computer-based wildfire scenarios, and this work yielded the first ranking of the most important factors used by ICs in issuing protective actions to threatened communities.  The key discovery in this research was that more experienced ICs place greater importance on dynamic, fire-behavioral factors but less-experienced ICs rely on static, community-based factors such as fuel in the community.

3) Advance our understanding of the role of saliency and uncertainty on identifying, selecting and activating triggers. The focus of this goal was determining whether the saliency of irrelevant information can negatively affect information processing leading to suboptimal choices (e.g. selecting “wildfire crossing a salient ridgeline” as the trigger condition merely because it's easy to detect the case where a wildfire crosses it).

4) Develop new computational models and associated software tools for setting effective triggers in the context of wildfires that can serve as the foundation for next-generation emergency decision-support systems.  The results of this research yielded:

a. A new method for guiding the decision of which households should evacuate, which ones should seek refuge, and which ones should shelter-in-place (home) in the final minutes before a wildfire impacts a community.  A key finding was that, as the amount of lead time (or time before impact) decreases, the number of households that are warned to seek refuge or shelter-in-place increases because evacuation has become too dangerous.

b. A new method for setting trigger points that can be used to inform the question of which households should take protective action and when (i.e. having households evacuate in small groups rather than all at once to minimize risk).

c. A new method for setting triggers for wildland firefighters so they can escape unharmed if a fire gets out of control.  A key finding of this work was that while the environmental conditions driving the fire are very important, the travel ...

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