Wildfire hazards don’t stop when the fire goes out

Fires sweeping through Los Angeles have left a massive path of destruction. At the time of posting, they have reduced more than 10,000 homes to rubble. At least 27 people have died so far.

One growing concern: post-wildfire hazards—that is, how toxic chemicals, mudslides, household debris, and dispersed ash could bring new, life-threatening dangers, said Farshid Vahedifard, Professor and Louis Berger Chair of the Civil and Environmental Engineering Department at the School of Engineering.

“While Los Angeles is struggling to contain fires, it also faces the high risk of post-fire ground failures such as debris flows and landslides,” he said, citing the recent case where a landslide split a house in two. 

“Wildfires can set off a cascade of events that can cause significant damage to buildings, natural environment, and people, and they can be deadly. They will happen quickly with the first rain, and that would be another disaster,” he said, citing the massive volume of debris flow following the 2018 Montecito fire that filled houses with mud. “The destruction doesn’t end when the fire is put out.”

Preventing that destruction before it happens is one of many dimensions to Vahedifard’s research, which includes a new model to predict post-fire rainfall-triggered landslides. His community-based studies also have brought him in close contact with wildfire-prone rural areas in California, where vulnerability is greatest. 

Through his surveys of several resource-constrained communities—and most recently, focus group research with emergency managers from nine California counties—he is advancing a nuanced understanding of the many challenges responders and residents face when threatened by local wildfires, and suggesting strategies for managing wildfires and their cascading impacts.

What he’s finding could help significantly reduce wildfire devastation, safeguarding both communities and critical infrastructure. Here are some key components:

Wildfire Building Codes

The issue of “fragmented and inconsistent” building codes can contribute to failures in protection, said Vahedifard.

One example is California’s Chapter 7A of the Building Standards Code, which provides guidelines for construction in Wildland-Urban Interface (WUI) zones. But “these codes are not universally applied across all wildfire-prone areas,” he said. “Communities outside the designated WUI zones, which are increasingly at risk due to urban sprawl and climate change, often lack mandatory requirements for wildfire-resistant construction. Even within WUI-designated areas, enforcement of wildfire-specific codes is inconsistent.”

The current wildfire crisis in Los Angeles illustrates the severe toll of these gaps; homes frequently fail to include basic wildfire-resistant features such as non-combustible roofing, ember-resistant vents, or fire-resistant landscaping, even in areas with a known history of wildfire activity.

At the university's inaugural Team Science Summit in November 2024, Vahedifard presented on strategies for reducing the vulnerability of disadvantaged communities to the impacts of cascading climate hazards. Photo: Paul Rutherford

The disaster in Los Angeles underscores the need for standardizing wildfire-resilient building codes that support a “unified, nationwide framework for wildfire resilience,” said Vahedifard. “We should use this opportunity to make sure that our building codes are ready to address fire resiliency and redouble efforts to inspect and ensure compliance.”

Advanced Risk Models

As climate change has intensified the frequency and severity of wildfires, there is a clear need for new risk models that incorporate climate projections, said Vahedifard. These predictive models incorporate climate projections, ember transport, and urban fire spread, and would prove indispensable tools for policymakers establishing codes based on robust and reliable risk assessments, he said. 

Developing new wildfire risk models that integrate climate projections requires a comprehensive approach that combines scientific research, policy initiatives, and industry adaptation is essential for improving wildfire preparedness and resilience, he said. 

“Collaboration between federal and state agencies, research institutions, and the private-sector agencies—like NOAA, FEMA, the U.S. Forest Service, and state fire and environmental agencies—plays a key role in advancing climate-informed risk assessments, while universities and research organizations contribute cutting-edge modeling techniques,” said Vahedifard. “Additionally, insurance companies, urban planners, and emergency management offices are increasingly investing in predictive models to assess long-term fire risks and financial impacts.”

The lack of a well-established wildfire risk model has cascading effects on related sectors, such as insurance and community resilience, said Vahedifard, especially in California, where insurers increasingly rely on proprietary models to assess wildfire risks, leading to skyrocketing premiums or outright denial of coverage in high-risk areas.

“When insurers cannot rely on uniform, evidence-based frameworks to evaluate risk,” he said, “it leaves homeowners underinsured or uninsured, further deepening the financial and social impacts of wildfires. And without reliable risk models, communities will struggle to make decisions about zoning, defensible spaces, and evacuation routes. They are ill-prepared for actual wildfire events.”

Proactive Technology Use

While other hazards like earthquakes or hurricanes have well-established risk models that are integrated into building codes, wildfire risk modeling remains underdeveloped, Vahedifard said.

Promising and sophisticated technologies, though, are now emerging. Satellite imaging and mapping technologies can visualize and assess geohazards (including wildfires as well as landslides and flooding), before they hit. 

By collecting more data around key factors such as land cover changes, dryness brought on by drought, or wetness due to exceptionally heavy precipitation, planners can help forecast the risk of intense fires and set the stage for more effective preparedness.

“Satellite imagery and climate data can be combined to give us a heads-up about what’s coming,” Vahedifard said. “We know that climate and land covers are critical precursors to wildfires. What we need are red flags. Emerging technologies can enable us to detect emerging trends and alert us to be cautious and proactively prepared.”

Clear Communication and Coordination

Improved risk communication tools are essential to reach vulnerable groups, including seniors, individuals with disabilities, and non-English-speaking residents, said Vahedifard. 

In conversations with emergency responders, the complexity and confusion surrounding multi-level collaboration also hindered effective wildfire management. “Their concerns included that unclear roles and responsibilities between state and federal agencies hinder response efforts, underscoring the need for better coordination and transparent communication at all levels,” he said.

“The devastation in Los Angeles highlights the urgent need for proactive preparation, as the risks don’t end when the flames are out,” he said. “Post-wildfire debris flows and landslides can strike quickly with the first heavy rain, causing further destruction. Strengthening predictive models, early warning systems, and mitigation strategies are critical to protecting communities from these cascading hazards.”