NIST study of 2007 “Witch Fire” north of San Diego

National Institute of Standards and Technology (NIST) have issued an in-depth study on fire behavior and defensive actions taken in a community during a Wildland-Urban Interface (WUI) fire.

“A Case Study of a Community Affected by the Witch and Guejito Fires,” report may be found at http://fire.nist.gov/wui.

First Detailed Look At Progress Of A Wildland-urban interface Fire

The NIST report is the first in a series of three publications to understand WUI fire behavior. The second publication, in progress, will examine the role of construction and landscaping on the probability of a structure’s survival. A third report will describe a study that uses the data to build a computer-generated virtual community to test the fire behavior predicted by different fire models and compare the results to the observed fire behavior and structural response.

This study is part of NIST’s Reduced Risk of Fire Spread in Wildland-Urban Interface Communities research within its Building and Fire Research Laboratory, a program to develop first-generation tools by 2013 for improved risk assessment and mitigation in WUI communities at risk from wildfires.

The “Witch Fire” A Wildland Urban Firestorm:

The new NIST study examines in detail the events in one representative community during the Oct. 21-22, 2007 “Witch Fire” north of San Diego, Calif. The Witch Fire was the largest of the 2007 California fire storm. The fire burned 197,990 acres (80,124 hectares) and destroyed more than 1,100 homes. Fire damage was estimated at $1.8 billion and suppression costs were $18 million.

For their study, fire researchers Alex Maranghides and Ruddy Mell tracked down every fire captain who worked in the fire at The Trails housing development in Rancho Bernardo to follow the fire’s evolution. The NIST researchers, with the support of The Trails Homeowners Association, also collected event timeline information from homeowners. Of the 274 homes in The Trails neighborhood, 245 were within the fire’s perimeter. Of those, 74 homes were completely destroyed and 16 were partly damaged.

Ember Attack Confirmed as main reason for structure loss:

The study revealed that two-thirds of all the homes destroyed were ignited either directly or indirectly by embers. “This is an important finding because current guidelines to make structures more fire resistant offer little guidance on how to make structures more resistant to an ember attack,” fire researcher Alex Maranghides explains.

Stay and Defend works:
Researchers also learned that one-third of all structures within the fire perimeter were defended by first responders and/or homeowners.