A retrospective analysis of the Palisades and Eaton wildfires, conducted by Cotality, found that 75% of properties within the fire perimeter for the Eaton fire and 37% of properties within the fire perimeter for the Palisades Fire were rated low-to-moderate wildfire hazard but had high conflagration hazard, emphasizing the importance of analyzing both factors when assessing risk associated with a structure.
Using its Wildfire Risk Score (WFRS) and Wildfire Conflagration Score products, Cotality deciphered why supposedly “low-risk” areas were devastated by the two fires, and highlighted the need for expanding the scope of traditional modeling.
Wildfire Conflagration
The Palisades fire, which damaged or destroyed nearly 7,000 properties; and the Eaton fire, which damaged or destroyed 6,600 properties, resulted in over $40 billion in insured losses. Both fires began as conventional wildfires but evolved into wildfire-induced conflagration, which occurs when “the fuel source switches from vegetation to the built environment,” according to the report. This “has profound effects on how and where the fire travels as well as how much potential destruction can occur.”
The report notes that although many of the structures were accurately evaluated as having low wildfire risk, “when examining the distinctive factors that contribute to structure-to-structure fire loss, these impacted properties were at heightened risk due to conflagration exposure.” As a result, areas that are considered “safe” from vegetation that can fuel wildfires must be re-assessed, as “certain properties, while categorized as a low wildfire hazard, are actually highly susceptible to conflagration hazard—especially in regions prone to wildfires.”
The two fires followed similar trajectories, with both beginning as vegetation-fueled wildfires and transitioning into destructive urban conflagrations; however, they behaved differently once they reached the built environment.
The Eaton Fire
Pre-Event Analysis
Of the 6,600 properties that were affected or destroyed during the Eaton Fire, 71% of the perimeter was considered a low wildfire hazard pre-fire, according to Cotality’s Wildfire Risk Score. Most properties, however, faced a heightened conflagration risk due to contributing factors such as building density, structure characteristics, wind and climate conditions, and the influence of embers.
Pre-event, Cotality estimates that “about 93% of all properties within the perimeter were considered to be at high and very high conflagration risk, based solely on [its] Wildfire Conflagration Score,” highlighting the importance of differentiating wildfire from conflagration risk and analyzing the two risks together for a comprehensive view of the overall hazard facing a structure.
Some Eaton properties burned from the initial wildfire, while others ignited later as the fire spread among structures. “Since the two hazards are not mutually exclusive, there were assuredly some properties that were damaged or destroyed due to fire types contributing to structure ignition simultaneously,” the report notes.
Post-Event Analysis
Cotality determined that 84% of the properties destroyed or impacted during the Eaton Fire had a low-to-moderate wildfire hazard but a high-to-very-high conflagration hazard, compared to its 79% pre-event estimate, using both the Wildfire Risk and Conflagration Scores.
The Palisades Fire
Pre-Event Analysis
“While sharing similarities with the Eaton Fire, the Palisades Fire had several different characteristics, including the amount and location of vegetation on and around a larger number of structures,” states the report. “While the majority of properties affected by the Eaton Fire had a low wildfire hazard rating, the Palisades Fire exhibited a more even distribution of wildfire hazard across the different categories, as identified by Cotality’s [WFRS].” Pre-event, it was estimated that 37% of the properties within the Palisades perimeter were low-to-moderate wildfire hazard while simultaneously a high conflagration risk.
Post-Event Analysis
Of the 7,000 properties damaged or destroyed in the Palisades Fire, nearly 48% were classified as low-to-moderate wildfire hazard, but were identified as having very high conflagration risk, according to the report. “By combining the analysis from both the WFRS and Wildfire Conflagration Score, [Cotality] identified 85% of the properties that were ultimately impacted within the Palisades Fire perimeter as having an elevated threat of damage—properties that a traditional wildfire hazard model alone would not have identified.”
Cotality’s findings highlight the limitations of traditional wildfire modeling that focus solely on vegetation-based risk while overlooking conflagration risk. The insurance industry can benefit from incorporating these risks into their assessment strategies as wildfire and conflagration events become increasingly commonplace.