Author(s): Stephen Badger. Published on November 1, 2018.

Large-loss Fires and Explosions in 2017

Driven by a historically destructive California wildfire, 22 large-loss fires last year resulted in 52 deaths, 233 injuries, and an estimated $12.5 billion in direct property losses


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NFPA reports annually on large-loss fires and explosions that occurred in the United States the previous year. Those fires are defined as events that result in property damage of at least $10 million. There were 22 such fires in 2017, resulting in a total of over $12.54 billion in direct property losses.

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Read the breakdown:
Selected 2017 Large-Loss fires in the United States.

In order to compare losses over the past 10 years, we adjust losses for inflation to 2008 dollars. When adjusted for inflation, the number of fires in 2017 that would have been categorized as large-loss fires—that is, fires resulting in a loss of $10 million in 2008 dollars—drops to 19, with an adjusted loss of slightly more than $11 billion.

In 2017, 13 fires, seven more than the previous year, resulted in more than $20 million each in property damage. These 13 fires resulted in a combined property loss of $12.4 billion, or 99.1 percent of the total loss in large-loss fires.

The two largest-loss fires in 2017 were so-called “fire siege” wildfire incidents that occurred in California. A fire siege is defined as multiple, simultaneous, long-burning wildfires that cover large land areas and create serious challenges for firefighters.

The first fire siege was a wildfire in Northern California, referred to by Cal Fire as the 2017 October Fire Siege, that burned 245,000 acres (99,147 hectares) or 335 square miles (868 square kilometers), caused $10 billion in damages, killed 44 people, destroyed an estimated 8,900 structures, and forced the evacuation of more than 100,000 people.

Leading up to the fire, AccuWeather reported a wetter than normal winter for 2016–2017 in California, which helped end a five-year drought. The precipitation contributed to ample vegetation growth, which subsequently become fuel for wildfires in the fall. In early October, 250 wildfires broke out. At the height of this wildfire activity, 21 fires burned out of control in six counties in Northern California. It has been reported that many of the fires were caused by downed power lines, falling power poles, and limbs falling on wires as a result of high winds. During this time, winds averaged 25–35 mph (40–56 kph), with gusts over 74 mph (112 kph). Diablo winds—hot, dry, offshore winds in north-central California—of hurricane force blew throughout the firestorm. Many of these large fires burned and merged with others to form fire complexes. One fire, the Tubbs Fire, became the most destructive wildfire in the state’s history, killing 22 people and destroying 5,643 structures.

A fire department helicopter flies near a fire burning in a 36-story apartment complex in Hawaii.

A fire department helicopter flies near a fire burning in a 36-story apartment complex in Hawaii. The blaze resulted in more than $107 million in damage. Photograph: AP/Wide World

With losses over $10 billion, the 2017 October Fire Siege produced the highest damage total in the past 10 years and the second-highest in NFPA’s records of U.S. fires. The only fire with greater losses, including adjustments to 2017 dollars, was the 9/11 terrorist attack on the World Trade Center in New York.

The second-largest loss fire of 2017 was the California Fire Siege Two, which occurred in December. Weather conditions leading up to the event were the same as those preceding the October fire storm. wrote that a “perfect” combination of ingredients came together: extremely dry conditions, plenty of dry vegetation ready to ignite, and hot, dry Santa Ana winds. The winds were strongest during the early part of December, clocked at 70–75 mph (113–121 kph). The winds helped the fires grow to thousands of acres in size in a matter of a few hours. At least 29 wildfires were ignited across Southern California, with at least six becoming significant fires. At least 230,000 people were evacuated. By the time the fires were extinguished, they had burned 307,953 acres and destroyed 1,355 structures. One firefighter and one civilian were killed, and 12 firefighters and seven civilians were injured. Damage from the December fires was estimated at $1.8 billion.

According to “Fire Loss in the United States During 2017,” published in the September/October issue of NFPA Journal, U.S. fire departments responded to an estimated 1,319,500 fires, which resulted in an estimated loss of $23 billion. Many of these fires were small or resulted in little or no reported property damage. Although the 22 large-loss fires accounted for 0.002 percent of the estimated number of fires in 2017, they accounted for 54.5 percent of the total estimated dollar loss. In human terms, these 22 fires accounted for 52 deaths, with another 233 injured.

For the eighth time in the past 10 years, a wildland/urban interface (WUI) fire topped the list of the year’s costliest large-loss fires in terms of property loss. In 2011, 2015, and 2017, WUI fires accounted for both the largest and second-largest fires in terms of estimated losses. In the past 10 years, there have been 29 wildland fires that accounted for more than $10 million each in direct property losses—14 accounted for over $100 million each, and three have accounted for more than $1 billion. In human terms, these 29 fires have been responsible for 80 deaths, 499 injuries, and totaled $17.7 billion in loss to property.

Firefighters battle a five-alarm blaze at a six-story apartment building under construction in Maryland.

Firefighters battle a five-alarm blaze at a six-story apartment building under construction in Maryland. The fire was among the costliest of 2017, resulting in losses of $100 million. Photograph: Ricky Carioti/The Washington post via Getty Images

In the past 10 years, 26 fires have occurred that each resulted in a loss of more than $100 million. Of these largest-loss fire events, 13 were WUI fires, 12 were structure fires, and one involved a U.S. Navy ship. These fires resulted in combined losses of more than $19 billion.

In 2017, there were three (or 12 percent) fewer large-loss fires than in 2016, but an increase of more than $11 billion (or 88 percent) in losses. Last year there were two (or 8 percent) fewer large-loss structure fires than in 2016, but the property loss associated with those fires was $399 million (or 53 percent) higher. There was one less large-loss non-structure fire compared to 2016, but the loss was more than $10.7 billion greater due to the large California wildfires of 2017.

Where the fires occurred and how

Of the 22 large-loss fires in 2017, 20 involved structures and resulted in a total property loss of $747.7 million, or 6 percent of the combined losses for all large-loss fires. The other fires included the two California WUI fires that resulted in combined losses of $11.8 billion, or 94 percent of the losses in all the large-loss fires.

Of the 20 structure fires, eight involved properties under construction; all were apartment complexes and several were within weeks of completion. The combined loss for these eight fires was $428.5 million.

Chart showing the largest of the large loss fires in terms of money lost

Four fires occurred in manufacturing plants—the facilities included a saw mill, a wood products manufacturer, a paper mill, and a slaughterhouse—causing a combined loss of $110.6 million.

Two fires occurred in apartment buildings, one with 569 units and the other with 60 units, with a combined loss of $129.4 million. Fires at two storage properties—a food storage warehouse and a plastic products recycling warehouse—resulted in combined losses of $31 million.

One fire each occurred in a high school (with $14.1 million in losses), an automobile dealership ($12 million), a country club ($12 million), and a hospital ($10 million).

In 16 of the 22 large-loss fires last year, the cause and origin of the fire were undetermined, unknown, or were not reported. In several cases, the destruction was so extensive that investigators could not make a definitive cause determination or could not rule out several possibilities. Other fires are still under investigation or causes have not yet been reported.

Cause was reported for six of the 22 fires, all of them structure fires. Two of the fires were incendiary: one in a 265-unit apartment building under construction, resulting in a loss of $110 million, and another in a hospital waiting area, resulting in a $10 million loss. Additionally, a fire caused by careless disposal of smoking materials at a country club resulted in a loss of $12 million; a fire started by hot work at an apartment under construction caused a loss of $12 million; a running generator ignited materials in an apartment building also under construction, resulting in $45 million in damage; and a fire in a food warehouse, started by a truck that caught fire outside, caused $21 million in damage.

Operating status was reported for 16 of the 20 structure fires. In eight cases, the facility was open, operating, or had workers on-site. Six were closed and the properties were unoccupied. At one fire, there was a security guard on duty, and at another there was a maintenance employee on-site. In four cases, the operating status of the property was not reported.

Ten of the structure fires broke out between 11 p.m. and 7 a.m. and had a total direct property loss of $315.7 million.

In addition to the 20 structure fires, the two WUI fires in California had a combined total loss of almost $12 billion.

Wildfire burns near power lines in California

Wildfires burns near power lines in California in December 2017 as part of a fire incident that became the largest in the state's recorded history, scorching about 427 square miles, destroying hundreds of homes, and resulting in nearly $1.8 billion in losses. Those losses paled next to the destruction caused by another California wildfire two months earlier, which produced losses of more than $10 billion. Photograph: Mike Eliason/Santa Barbara County Fire Department via AP

Smoke detection and automatic suppression equipment

Information about automatic fire or smoke detection equipment was reported for 15 of the 20 large-loss structure fires. Of those 15 fires, 12 properties had smoke alarms present and three had no automatic detection equipment installed. Five of the 12 systems operated as designed; six systems did not operate, and in one case the operation was not known. Five of the six systems that did not operate were either not completely installed or had been shut off prior to the fire due to construction. No reason was given for one of the systems not operating.

Information about automatic suppression equipment was reported for 16 of the 20 structure fires. In those 16 fires, nine properties had suppression systems present and seven had no systems present. In six cases, the systems did not operate because the sprinkler systems were shut down prior to the fire or the systems were not yet complete due to construction. In one case, the system operated and kept the fire from spreading. The operation of systems in two of the fires was not reported.

Complete information on the presence of both detection and suppression equipment was reported for 15 of the 20 structure fires. Nine structures had both detection and suppression equipment, three had no detection, and three had neither system present.

What we can learn, where we get our data, and acknowledgements

Adhering to the fire protection principles reflected in NFPA’s codes and standards is essential if we are to reduce the occurrence of large-loss fires and explosions in the U.S. Proper construction, proper use of equipment, and proper procedures in chemical processes, storage, and housekeeping will make fires less likely to occur and help limit fire spread should a fire occur. Proper design, maintenance, and operation of fire protection systems and features can keep a fire that does occur from becoming a large-loss fire.

NFPA identifies potential large-loss incidents by reviewing national and local news media, as well as fire service publications. A clipping service reads all U.S. daily newspapers and notifies NFPA’s Applied Research Division of major large-loss fires. NFPA’s annual survey of the U.S. fire experience is an additional data source, although not the primary one. Web searches have proven useful in several cases where fire department and government reports have been released and published.

A gas explosion and fire at a high school in Minnesota killed two and resulted in more than $14 million in damage. Photograph: David Joles/Star Tribune via AP

Once a fire has been identified, NFPA requests information about it from the fire department or jurisdictional agency. We also contact federal agencies that have participated in investigations, as well as state fire marshals’ offices and military sources. The diversity and redundancy of these data sources enables NFPA to collect the most complete data available on large-loss fires. This report includes only fire incidents for which NFPA has official dollar-loss estimates; other fires with large losses may have occurred, but are not included here because no official information has been reported to NFPA.

NFPA would like to thank the U.S. fire service for its contributions of data, without which this report would not be possible. In some cases, the fire department, forestry officials, or government officials were unable to contribute complete details to NFPA because legal action is pending or ongoing, the incident was of a sensitive nature, or the size of the situation was overwhelming and reports had not yet been released. The author also wishes to thank Nancy Schwartz and the staff of NFPA’s Research group for providing the support this study requires.

STEPHEN G. BADGER s a fire data assistant in NFPA’s Applied Research Group and a retired firefighter from the Quincy, Massachusetts, Fire Department. Top Photograph: Ted Pendergast/