La Fire’s charred Wildland Urban Interface. Here’s what it is- quiet

In just a single month, 2025 is the second most destructive fire year in California history, with more than 16,000 homes and other structures damaged or destroyed by two fires in the Los Angeles area. Most of these structures were in neighborhoods where the boundaries between human development and natural landscapes blur area’s fire officials and researchers call Wildland Urban Interface or WUI (WOO-EE).

As a fireplace approaches one of these areas, the results can be dangerous as a fire can change from consuming trees, shrubs and plants to devouring homes and other structures that are often constructed in ways that are vulnerable to burning. And this is also where California has built home for decades – almost 45% of the homes built between 1990 and 2020 are located in places with lots of vegetation ready to burn a fire.

A Calmaters analysis has found that from 2020, nearly 14 million Californians, or 1 in 3, lived in the scattered zone of 7 million hectares that make up WUI. And this is not just a problem for Californians living in the rural areas of the state: All 58 counties in California have Wuis together with many areas across the country. Wui grows by approx. 2 million acres a year nationwide, according to US Fire Administration.

Sarah McCaffrey, a social scientist who worked for the US Forest Service for decades, expressed it in a different way: Structural Fires and Wild Fires – and the interface are where the two meet.

Just because a development is located within WUI does not mean that a fire will occur, but there can be deadly and destructive consequences if you do. While less than 3% of the state WUI has been affected by fireplace in the last decade, thousands of homes in the zone have been destroyed, according to a Calmaters analysis.

“I think it’s sometimes more useful to talk about building in high wildfire fare.”

Judson Boomhower, Deputy at the Economics Department of UC San Diego, at Wildland Urban Interface

Since 2018, Cal Fire, the State Fire Agency, has inspected all the buildings within 100 meters of a fire converter and assessed the damage level. The most destructive fires in the history of California have largely damaged or destroyed home within WUI, including the two largest fires in Los Angeles County this year – Palisades and Eaton Fires that demolished entire neighborhoods and killed 28 people Per. January 24.

The Eaton fire killed at least 17 people and destroyed more than 9,400 structures, approx. 9,200 Of which was within Wui as much of Altadena, where the San Gabriel valley rises to meet the San Gabriel Mountains. The map below shows inspections of buildings performed by Cal Fire after the Eaton fire together with WUI, which illustrates how destructive a larger combustion can be for suburban areas.

The other big fire in LA, Palisades Fire, apparently drove down the Santa Monica mountains towards the Pacific Palisades, a coastal district in Los Angeles, located almost exclusively within WUI. The winds in the hurricane stood and spread the flames and destroyed at least 6,800 structures while nearly 4,100 was undamaged.

The deadliest and most destructive fire in California history, the camp fire, destroyed the city of Paradise in Butte County in 2018, when the massive flame burned both the natural and built environment. The fire damaged or destroyed nearly 20,000 structures and killed 85 people.

Having a home in Wui does not guarantee that it will burn down if a fire is opening the neighborhood. Many factors contribute to this option, such as the year in which the home was built, nearby fuel management practices aimed at reducing nearby flammable objects – and what some people call “weather” and the rest of us call “luck.” Therefore, there are photos of undamaged homes next to their raged neighbors after so many destructive California’s fires.

Despite all this, some experts say Wui is not the only one, or maybe even the best way to measure fire hazard or risk because it wasn’t designed for it. Focusing our attention can be collapsed.

“There is nothing about fire risk on the WUI card,” McCaffrey said. “There are some papers that show that about a third of houses lost in fires are not in WUI, right? But we are targeting all our attention to WUI. “

An example of how the boundary between the wild and urban landscape is not necessarily translated into high fire risk is Tubb’s Fire 2017 in Sonoma County. The Coffey Park quarter in Santa Rosa was almost leveled, although not technically in WUI, right next door. The fire destroyed more than 5,000 structures and killed 22 people.

“There is actually a legal or technical forestry definition of the wild city limits, and that has to do with the number of structures per year. Acre and the amount of vegetation, ”said Judson Boomhower, an assistant professor in the finance department of UC San Diego. “I think it’s sometimes more useful to talk about building in high wildfire fare.”

The ways to reduce the risk that fire spread from house to house depends on the nuances of every neighborhood, especially how tightly packed the buildings are.

“If houses are, you know, 80 or 100 feet apart, then all our focus is on proper space and zone zero and all that probably makes much more sense,” McCaffrey said. “Because then, you know it’s a good chance that my house could survive if I’ve done all this, even if my neighbor’s house is burning.”

On the other hand, some of the homes of the Pacific Palisades look so close together that even to make sure there is nothing flammable within five meters, may not have prevented the spread of the fire, McCaffrey said. ONE law Signed by Head of Government Gavin Newsom In September 2021, the State Board of Forestry and Fire Protection and State demanded four Marshal to come up with suggestions to create an Ember-resistant zone within five meters of a structure in a high fire magazine.

The state’s intervention has helped reduce destruction in these more vulnerable areas with fireplace. Research from 2021 concluded that California’s home, built after 2008, was almost half as likely that they were destroyed compared to those built in 1990, if a fire burned through the neighborhood, largely due to improved building code managers.

California faces a chronic housing shortage and megafires increased by climate change, but with millions of residents already living in the wild urban interface, government decision -makers will face questions about how to protect people and where to rebuild Disaster strikes.