1985 Department Store Explosion
On March 24, 1985, a powerful explosion devastated a Ross Dress for Less department store in the Wilshire-Fairfax District of Los Angeles, drawing national attention to the dangers of methane gas beneath urban developments. The blast injured more than twenty people, shattered windows, partially collapsed the building, and scattered debris throughout the surrounding area. Witnesses reported flames erupting from cracks in nearby pavement as emergency crews responded to the scene.
Explosion Caused by Methane Gas Underground
Subsequent investigations determined that methane soil gas had accumulated beneath and within the structure before igniting. Scientists and engineers concluded that methane migrated upward from the subsurface and entered the building, where it collected in enclosed areas until an ignition source triggered the explosion. The incident highlighted the risks associated with methane, particularly in areas where natural geologic conditions can allow methane gas to migrate into buildings and other enclosed structures.
The explosion occurred within an area historically influenced by petroleum production and naturally occurring hydrocarbon deposits. Investigators identified elevated methane concentrations beneath the site and conducted extensive drilling and gas monitoring to better understand the source and movement of the gas. The event remains one of the most significant methane-related incidents in Los Angeles history and serves as a landmark case study in subsurface gas hazards.
Methane Building Safety Codes
As a direct result of the disaster, the City of Los Angeles expanded its focus on methane safety, ultimately leading to the development of modern methane testing, methane mitigation, and building protection requirements. Today’s methane regulations, including methane zones, methane buffer zones, methane soil gas surveys, and methane mitigation systems, trace much of their origin to lessons learned from the 1985 explosion. These requirements help protect future developments from the risk of methane gas intrusion, combustible gas accumulation, and explosion hazards.
The photographs above illustrate the extent of the March 24, 1985 Los Angeles department store explosion and demonstrate why methane testing and methane mitigation have become critical components of development throughout methane-affected areas of Southern California.
