The Rim Fire, which ignited on August 17, 2013, had become the fifth largest fire in California history by the last day of the month and continued burning largely uncontained in the opening days of September. At 219,277 acres consumed on August 31, the fire closely approached the fourth largest fire, the Matilija, which burned 220,000 acres in 1932. The largest fire was the Cedar Fire in San Diego County, which burned 273,246 acres in 2003. This rapidly expanding fire has also been reported as the largest known fire to burn in the Sierra Nevada Mountains.
The Moderate Resolution Imaging Spectroradiometer (MODIS) flying aboard NASA’s Terra satellite captured this true-color image on August 26. Red hotspots mark areas of actively burning fires on the perimeter of the Rim Fire (south). The smaller fire to the north is the American Fire, which started on August 10 and reached 100% containment on August 29, after consuming 27,440 acres.
By August 31, the Rim Fire had charred 219,277 acres, or about 342 square miles of brush, oak and pines. About 4,500 structures remain threatened, some on both the east and the west side and approximately 6% of Yosemite National Park’s back country is also in flames. The fire is approaching two of the park’s stands of giant sequoias, the Tolumne and Merced groves. The Mariposa grove, home of the 1,800 year-old Sequoia known as the Grizzly Giant appears safe.
Fire is not necessarily a tragedy for healthy sequoia trees- it can actually be a friend, as the cones require fire for germination, and ground fires improve the chance for germinating seeds to take root by clearing brush and fuel from the forest floor. The trees themselves have a thick, resilient bark on the lower section of the trunk, which is highly protective against flame. Sequoias are not flameproof, however, and high-temperature fires, especially crown fires, are capable of killing even the oldest trees. The Rim Fire has been a high-intensity fire, leaping from crown to crown in forested areas, but ground fire is also occurring. The fate of the trees will depend on the fire intensity, and predictions tend to be optimistic.