CSI Fire: analyzing a scene of wildfire destruction

Blog Post created by michelesteinberg Employee on Oct 23, 2012

Five years ago at this time, San Diego County was under siege by a large and destructive wildfire – the Witch Creek/Guejito Fire complex would ultimately destroy more than 1,600 structures in October and November of 2007. I accompanied a video crew from Boston to obtain footage of damaged and undamaged homes, and to document what I could to try to make sense of the events that had led to such destruction.

The National Institute of Standards and Technology (NIST) also had staff on scene from their fire research division focusing on wildland/urban interface fire. NIST researcher Alex Maranghides was initiating the first steps of intensive post-fire investigation and analysis in a specific portion of a subdivision that would lead to an important report on these fires and further study by NIST and its partners.

Our team caught up with Alex on scene in the subdivision, a community characterized by wide, paved roads, large homes, and a great deal of home destruction. We spent more than an hour on one lot,IMG_1256 fascinated by the green lawn on one side of the completely destroyed home, and the green, undisturbed brushy vegetation on the upslope to the home. We observed the blasted trees that showed the worst burning on the house-facing sides. Very large embers lay in the well-kept grass (my foot shows the scale). If it wasn't the grass or brush that caused this home to burn, what was it?IMG_1245

Other houses. The huge chunks of burned material that had flown through the air were once part of someone else's roof, or siding, or even insulation from an attic. When they landed in the green, watered lawn, they self-extinguished – no fuel for the fire there. When they landed in gutters or a deck or piled up next to the garage wall…another story. Once the house ignited, it burned for hours. In a fire as big and broad as this complex, there was no way for fire fighters to defend each home. The simultaneous exposure of dozens of homes to wildfire (NIST's study calculates 22 houses per hour were burning at the height of the event in this subdivision) meant that traditional fire defense simply could not work.

I had a million questions for Alex, but I also felt like I was suddenly inside a virtual textbook of "how homes ignite." I'd been learning about this phenomenon since 1998 through Firewise workshops, through watching Jack Cohen's DVD (Wildfire! Preventing Home Ignitions) and by sitting through training sessions to learn how to assess homes for wildfire hazards. I asked Alex if he thought the home had had a wood shake roof. Moments later, he quietly pointed out the evidence to me.IMG_1281

If you'd told me just a week before this fire that I would be obsessively taking pictures of staples, I might have thought you were a little strange. But to see the clear evidence of the roof staples that had held wood shingles in place…maybe I'M a little strange but it took my breath away. The abstract principles and photos of past events suddenly came to life for me.

We spent more time that day filming parts of what would become a public service announcement, finding a completely destroyed home next to one that was saved by employing Firewise principles. The scene in this upscale neighborhood was eerily quiet, with only our crew, CAL FIRE staff, and the occasional landscape maintenance vehicle or police car passing by.  The next day, we visited a more modest community where residents were on scene, beginning the heartrending work of salvage and coping with loss.

Photos: Burned fire evacuation plan found at homesite, Rancho Bernardo, California (top); destroyed home with green vegetation visible on the adjacent slope (top right); firebrand/ember from burned home (center right); roof staples for wood shakes at scene of destroyed home (bottom right). All photos by Michele Steinberg, November 2007.