Thousands of people didn’t evacuate before Hurricane Matthew. Why not?

The problem is that many people have short memories – even in highly vulnerable areas. In Charleston, hurricane evacuation experience during Hurricane Hugo in 1988 strongly predicted evacuation decisions four years later during Hurricane Emily. However, when Hurricane Fran made landfall some 170 miles to the north eight years later, many residents had adjusted their risk perceptions and decided not to evacuate. After all, there hadn’t been a bad hurricane in nearly 10 years.

A similar pattern occurred during Hurricane Katrina in 2005. After hundreds of thousands of Louisiana and Mississippi residents evacuated ahead of Hurricane Ivan in 2004, the storm weakened from Category 5 to Category 3 and moved east, making landfall in Baldwin, Alabama and causing minimal damage in Louisiana and Mississippi. As a result, many residents questioned the need to evacuate a year later as Katrina approached.

Protecting the most vulnerable
Cost is typically a weaker predictor of behavior. Generally, up to 75 percent of evacuees can stay with friends or family. But for those who cannot, the costs of fuel, hotel rooms and lost wages can significantly impact family budgets. One recent study calculated that evacuating before a Category 3 hurricane would cost a household approximately US$340 to $525. Timing matters too: Weekend evacuations can cost less, particularly for those without paid sick leave or vacation time.

While these costs may seem modest compared to the risks of staying in place, households that cannot afford to evacuate are also vulnerable in other ways. They are more likely to be located in flood plains or to live in mobile homes, and to lack reliable family transportation.

This is particularly true in the southeastern United States. Between 2000 and 2012 populations in the southeastern Atlantic and Gulf Coast census regions increased nearly twice as fast as the national average. Along with this growth, the proportion of coastal residents who are socially vulnerable – for example, who are elderly, work in low-wage service industry jobs or belong to racial and ethnic minorities – also rose. In eastern North Carolina, a high-poverty region, many residents displaced by post-Matthew flooding cannot afford to replace damaged goods or repair their homes.

But it’s not all about money. Residents who have personal transportation and the financial means to evacuate do not always go. Having a strong social support network tends to correlate positively with good health: For example, if you have a larger and stronger social network you have a lower risk of age-adjusted mortality. But in disasters those social support networks may actually represent responsibilities that prevent people from moving out of harm’s way.

This dynamic was clear in New Orleans during Hurricane Katrina. While many residents were criticized for failing to evacuate, they made this decision based on shared norms, local culture and traditions, responsibilities to social networks and a collective history that led them to trust their social networks rather than following instructions from authorities.

While the evacuation of New Orleans for Katrina was widely viewed as a debacle, it actually succeeded on many counts. According to the National Academy of Engineering, more people were able to leave the city in a shorter time than was even thought possible.

However, many who couldn’t move were triply vulnerable: they had low incomes or lacked transportation, lived in older homes in flood-prone neighborhoods and had little access to or influence on the development or implementation of local disaster plans and policies. We need to do more work to translate bad experiences like this into policies that can protect residents’ health and safety, while also respecting inherent community strengths that sometimes lead to evacuation failures.

Preparing for the next storm
It remains to be seen how well evacuations ahead of Hurricane Matthew succeeded. Available information indicates that 35 to 50 percent of people affected by mandatory evacuation orders throughout the storm zone complied. These rates are comparable to prior evacuations. And as in past storms, some coastal residents moved away from storm zones only to be trapped there by inland flooding.

As of October 16, 44 deaths had been attributed to Hurricane Matthew in the United States. They include residents who drowned after driving onto flooded roads; crush injuries and trauma from trees falling on homes and cars; and inappropriate use of generators. There will be more deaths and injuries as residents return home to clean up and are exposed to fallen power lines, mold and other stresses that exacerbate existing chronic health conditions.

It will take longer to calculate how many deaths and injuries could have been avoided if more people had followed evacuation orders, and to repair storm damage. Rebuilding, and making hard choices about where not to build again, will challenge residents and policymakers. But it is critical to grapple with these issues so we can do a better job responding to the next storm, which likely won’t be ten years away.

Jennifer Horney is Associate Professor of Epidemiology and Biostatictics, Texas A&M University. This article is published courtesy of The Conversation (under Creative Commons-Attribution / No derivative).