Wildfires or wildland fires are a natural hazard that poses a threat to both lives and property, can be difficult to control, and can cause wide-ranging destruction.
The following is a brief synopsis of historical wildfire events, a high-level view of wildfire science, and a discussion of the tools available to mitigate this threat.
Wildfire is not a hazard or phenomena unique to North America, though each year there are numerous reports about such events in states like California. Major wildfires have occurred throughout the world in Australia, France, Germany, Greece, Indonesia, Italy, Poland, and Russia. The consequences are typically measured in terms of hundreds or thousands of buildings destroyed, number of lives lost, and millions of dollars in property damage and resources spent fighting the wildfire.
Notable global wildfire incidents include:
Devastating wildfires have common characteristics. They can occur whenever there has been unusually warm or hot temperature for an extended period of time combined with low humidity and lack of rain. This combination of weather conditions leads to dry brush, trees, and grass, making the area more susceptible to fire from natural or human-initiated causes.
Wildfires are usually driven by strong surface winds. Adding to the phenomena, a wildfire also creates its own weather atmosphere as it burns. The hot flames and gases rise rapidly from the fire and displace the relatively cooler surrounding air. This displacement leads to surface wind patterns that can blow at speeds of 70 miles per hour—near-hurricane force.
This creates a fast moving fire front that consumes the dry brush and any other combustible material, including structures.
As population centers expand and more people build homes at the edge of forest or wildland areas, there are more people and structures at risk. Some estimates show the number of persons exposed to wildland fire doubled from 1970 to 2000.
The Insurance Services Office (ISO) has created a model for assessing the wildfire risk to an area. The model for the United States combines satellite images and information regarding soil conditions, land slope, vegetation, and access roads. This model, according to ISO reports, classified 97.5% of the area burned in the 2003 San Bernardino fire as having fuels (e.g., tall grass, trees, dense brush, and forest) conducive to and favorable for wildfire conditions.
Many major US municipalities offer wildfire risk maps that identify areas at risk to wildfire. These include the Association of Bay Area Governments (ABAG) in California, as well as local and state agencies in Colorado, Oregon, and Florida, among others. Various international agencies also promulgate wildfire risk maps and mitigation guidelines. Among these are the European Forest Fire Information System (EFFIS), Fire Protection Association of Australia, Russian Federal Forestry Agency (FFA), and Italy’s Central Functional Centre.
Wildfire mitigation strategies focus on creating awareness of wildfire conditions and prevention of dry vegetation and fuels in close proximity to inhabitable structures, especially when such conditions persist.
Awareness efforts focus on alerting persons to the need for extreme caution with cigarettes, campfires, trash burning, and any other flame or fire use during periods when the wildfire danger is extremely high. Bans are typically issued for open flames when the potential conditions exist.
Prevention, aside from controlling open flames, focuses on removing the fuel near structures. Creating a defensible space, as it is called, helps reduce possible fire travel from burning brush to the structure and allows fire fighting personnel to make a defensive stand to protect the structure. Many organizations in wildfire-prone areas maintain such a space regularly as best practice.
The National Fire Protection Association (NFPA) addresses wildfire danger and prevention with Standard 1144, “Standard for Reducing Structure Ignition Hazards from Wildland Fire,” which organizations in wildfire-prone areas should review and seek to implement well in advance of a wildfire event.
A primary focus of such efforts should be best practice defensible space creation activities such as the following:
Organizations located in an area susceptible to wildfire should have an emergency evacuation plan along with a business contingency plan. Many times there is only a few hours advance notice of evacuation during a wildfire event. It may also be several days before authorities allow access to a fire zone following evacuation. In the event of building damage, the resumption of operations may be delayed.