Fire Walk With Me

As I pulled up to the recently released scene of a 3,200-acre wildfire, I was greeted by hundreds of acres of charred, blackened earth and tree stumps. Prior to arriving on the scene, I obtained a lightning strike analysis report for the entire area for the past 14 days—it showed no strikes. To me, that meant the fire most likely was caused by humans.

Because several dozen homes had fallen victim to the fire, the public and many insurance companies wanted answers. As I began to survey the area, I thought, “Stick with the methodology outlined in NFPA 921 that you’ve used on nearly every wildfire investigation, and leave no stone unturned.”

A Wild Year

What a year it has been so far. U.S. wildfires continue to plague homeowners, firefighters, and insurers. As of mid-July 2016, the National Interagency Fire Center reported that over 28,244 wildfires have destroyed over 2.4 million acres. In Canada, over 2.5 million acres have been consumed from nearly 3,400 reported wildfires. Foresters reported that there are over 66 million dead trees in California alone due to extended drought and poor forest health. Vast portions of Colorado and British Columbia have hundreds of thousands of acres of dead and dying trees due to beetle infestation.

Where does this leave the insurance industry? As more homes are constructed in the wildland/urban interface zone—the area in which forested land and homes/communities meet—these wildfires are becoming more problematic, harder to control, and more expensive every year. The impact to the industry continues to rise at an exponential pace.

Back to the Scene

I began the investigation by interviewing some of the first arriving firefighters and law enforcement personnel. Through their observations and their mobile phone pictures and videos, I immediately was able to narrow down the 3,200 acre fire’s beginning point to one or two acres, known as the general origin area (GOA). The other 2,998 acres were not important to me right now. Two circuits of the GOA were done in a clockwise then counterclockwise direction to examine burn indicators that depicted what direction the fire had traveled.

Weather data such as wind speed and direction, relative humidity, and ambient temperature all have an impact in determining both origin and cause. The firefighters provided me with copies of their size-up information, which had the weather at the time of the event. Topography analysis is important, too. Aspect, slope, chimneys, and canyons play into origin determination because they can affect the direction in which the fire spreads.

Fuel analysis also plays a significant role. Did the fire occur in fine, flashy fuels, dead fuels, or diseased fuels? What was the fuel type and fuel moisture at the time of the fire?

While walking the perimeter of the GOA, I noticed many distinct “macro patterns.” These macro patterns included larger burn patterns on heavy fuels, power poles, staining on rocks, needle freeze, char patterns, white ash deposits, and bevel patterns on some heavy fuels. Over the course of several hours, I followed the macro patterns that depicted where the fire had advanced back to where it became more subtle and transitioned to a backing pattern rather than an advancing pattern. A backing pattern leaves more subtle patterns in which the fire fights against the wind and/or topography. Staining and grass stem positions often are present in backing patterns.

This area where both the transition and number of macro patterns from an advancing fire become more subtle, and signs of a backing fire become evident, is called the specific origin area (SOA). I like to narrow down a general origin area of one or two acres to an SOA of approximately 10-20 square feet.

Now the work really starts. I get on my hands and knees and perform a grid search, looking for micro patterns. “Get out the magnifying glass and magnet,” I remind myself.

Throughout the entire morning, I use red flags to mark areas in which the fire advanced or moved forward with the wind or topography. I note the flank, or sides, of the fire with yellow flags to indicate where lateral patterns are seen. Finally, areas in which the fire backed or slowly crept back against the wind or topography are marked with blue flags. Spot fires, or fires that result from flying embers, cause me to re-evaluate the patterns to determine if they are in the correct area.

Once a specific area of origin is determined using this macro-pattern analysis, I begin to focus on micro-pattern analysis. Micro patterns may include shadowing on pine cones, staining on berries or animal droppings, curled grass, and slight staining on smaller fuels. I mark these micro patterns with flags, too. A grid is used to begin the search for the specific cause of the fire within the area of origin. String lines are placed about 12-18 inches apart, and are set up in a parallel pattern. Then I carefully search each area in the grid visually, then with a magnet.

Some possible causes of wildfires include lightning, flares, catalytic converter heating, carbon flakes from exhaust, friction sparks from railroad trains or heavy equipment, fireworks, firearms, cigarettes, holdover fires, escaped campfires, electrical power lines, and welding operations. An incendiary cause is when an intentional act occurs, resulting in the crime of arson.

It was getting late in the day and my eyes began playing tricks on me. There always are one or two patterns that contradict what the majority of other patterns are showing, which can be intriguing and confusing. “Focus on what the majority of the burn patterns are telling you,” I think. “Stick to the grid search, follow the indicators, and don’t just focus on looking for an obvious cause.”

I thought to myself, “Have I really used over 60 flags and taken over 95 pictures so far?” As I began to search the sixth grid lane, an area that had a more mottled burn appearance and where there was actually less heat damage, I turned up a surprising find: several matches.

After taking more pictures and gently scooping up the ground fuel under the matches with a flat edge, I place them gently onto a cookie sheet and wrap it, thereby preserving the evidence perfectly. “Don’t give yourself a pat on the back just yet,” I thought. “Continue the grid until you are completely into all backing indicators.”

In grid lane eight, I found a cigarette lighter. After taking more pictures, GPS readings, and placing the lighter into an evidence bag with gloved hands, I decide that I am finished for the day. It is now time for law enforcement officers to get involved and find out who may have had a part in this wildfire.

Between 70 percent and 80 percent of wildfires are human-caused, whether the cause is from arson, misuse of equipment, or equipment failure. This opens up many subrogation, civil and criminal actions to be considered.

Wildfire investigations are daunting for investigators trained in structure fire origin and cause because they are investigated from the area of most damage to that of the least, which is opposite of the methodology used in structure fires. Thus, a fire investigator with specific training should be retained. An investigator with additional wildfire suppression experience can be invaluable to understanding the fundamentals of wildfire behavior.