Researchers delve into Kincade fire evacuation trends

When Sonoma County officials ordered nearly 200,000 residents to flee the potential path of the Kincade fire in 2019, their goal was getting as many people as possible out of harm’s way, and making sure everyone had enough time to flee.

They also created a trove of data that a group of international researchers are hoping to study so that Sonoma County and other wildfire-prone communities can better plan for future large-scale blazes.

As one part of their project, researchers are surveying people who lived in Sonoma County during the Kincade fire, which sparked Oct. 23, 2019, from high-voltage PG&E transmission lines in the Mayacamas Mountains east of Geyserville.

A second line of study will involve reviewing four weeks’ worth of anonymous cellphone GPS data in Sonoma County beginning a week before the fire’s start.

While there’s a large body of research regarding evacuations in other types of emergencies in the U.S., few studies have examined what motivates people to flee in wildfires, said Xilei Zhao, an assistant professor at the University of Florida’s civil engineering program and a lead researcher for the two studies. Unlike hurricanes, wildfires come with environmental cues like smoke and flames that can heavily influence people’s decision-making process, Zhao said.

“Wildfire scenarios are becoming more and more severe and the evacuation scales are becoming larger and larger, so I see it as a very pressing need,” Zhao said of the research. “If we study the Kincade fire very well and develop a robust plan in Sonoma County, they can definitely use it to prepare themselves for future events.”

The size of the Kincade fire and large number of people ordered to evacuate — about 190,000, or more than a third of the county — were among the reasons Zhao and her colleagues chose the blaze as their case study, Zhao said.

Her team, which is made up of researchers from New Zealand and Australia, needed to select a large enough wildfire to ensure they’d be able to collect enough data, she said.

The survey, which ranges between 43 and 66 questions depending on the respondent’s answers, includes questions about whether emergency officials or friends informed participants that they were under mandatory evacuation order. Other questions ask where people lived and whether they evacuated, and if they saw or heard flames before making their decision.

The survey, which was opened over the summer, will be available through the end of the year, Zhao said. It can be accessed from the University of Florida Transportation Institute Facebook page.

Nancy Brown, the Community Preparedness program manager for Sonoma County’s Department of Emergency Management, said she’s doing outreach with local community groups in order to boost participation in the survey.

The insights gathered by Zhao’s team could help the county better understand why people choose to evacuate and how long they are gone.

That information could lead to changes in how and when county emergency officials deploy resources, or give firefighters more information about how long it takes people to get out of harm’s way.

“It’s just exciting when you see something like this happening. These are not studies (Sonoma County) could commission,” Brown said, adding that this type of research typically requires thousands of hours to complete. “To have access to this and be able to support it is a great opportunity for us.”

Brown was also curious how other communities outside of Sonoma County, particularly those less experienced and vigilant about wildfires, might incorporate the research in their own emergency planning, she said.

For the second part of the study, Zhao’s team will review the GPS data to model evacuation behaviors, making this study the first to examine how people flee a wildfire. Researchers will be able to track precise evacuation times for those who did choose to leave and the route they chose to make their escape.

Other researchers have used the GPS data to study people’s movements, though that analysis usually examines people’s normal day-to-day travel. She knows of one research group in Japan applying the technology to earthquake evacuations.

“We want to tell, for different neighborhoods, how long it’s going to take to evacuate and what timeline do we have before the fire is too close,” Zhao said. “We want to give people good information about what route they need to choose and what time they need to evacuate.”

You can reach Staff Writer Nashelly Chavez at 707-521-5203 or nashelly.chavez@pressdemocrat.com. On Twitter @nashellytweets.