Bruce Malamud of King's College London and his colleagues analyzed records from more than 88,000 wildfires that occurred in the U.S. between 1970 and 2000. Both the size and frequency of the fires track what is known as a power-law relationship, which accounts for the fact that small fires occur most frequently and the largest ones are the least likely to occur. The team also discovered a distinct pattern in the size of wildfires based on geography: going from east to west, the ratio of small fires to large ones decreases. Differences in population trends and forest fragmentation could be to blame, the authors suggest.
The researchers also assembled a map of fire patterns and potential risk for 18 different regions across the country. The results, they conclude, allow "for the classification of wildfire regimes for probabilistic hazard estimation in the same vein as is now used for earthquakes."