Community Response to Hurricane Threat: Estimates of Warning Diffusion Time Distributions

Abstract

The data on warning diffusion rates over time are generally sparse and are extremely limited for hurricanes. This is a potential problem for transportation analysts who are trying to compute evacuation time estimates for coastal jurisdictions. The available data indicate that 20%–50% of the households in areas at risk continually monitor local news media as soon as a hurricane is within 72 h of possible landfall in their area. Moreover, this percentage rises to 60%–80% within 64 h of landfall and over 90% within 48 h of landfall. The data from hurricane studies are consistent with data from another slow-onset hazard (the arrival of the Indian Ocean tsunami in Mauritius) and a somewhat less severe hazard (the Boston water contamination incident). There appears to be no data on warning diffusion in hurricanes with late intensification or late-changing tracks. However, the available data on warning sources in these types of hurricanes suggest that the rates of diffusion of local evacuation warnings would be comparable to those in other rapid-onset events.