Damage from the Guadalajara explosion. Source: Disaster Recovery Journal.On Wednesday, April 22, 1992, the city of Guadalajara, Mexico, experienced a series of massive explosions in the heart of the downtown Reforma district that were caused by the ignition of gases in the city's sewer system that had been generated by the leakage of gasoline. The multiple blasts over a period of about four hours tore apart miles of sewer lines and, in the worst-hit places, left heavily-trafficked streets in a pile of rubble sitting in 25-foot-deep sewer trenches. The explosions crushed to death 206 people; injured 1,460 people; damaged 1,148 buildings; and destroyed 350 businesses and 505 vehicles. In addition, the disaster left about 15,000 people homeless. The two largest explosions measured 7.1 and 7.0 on the Richter scale at the University of Mexico in Mexico City some 200 miles away. The political fallout rocked Mexico for years because local authorities knew of a gas leak problem for days but chose not to evacuate the population.

A few days before April 22, 1992, residents of the Reforma district in the heart of downtown Guadalajara began to notice a persistent odor reminiscent of gasoline and other chemical odors emanating from their toilets and drains. At first, many residents ignored the odor, attributing it to the annual spring cleaning of the nearby gasoline storage facility called La Nogalera. Pemex (short for Petroleos Mexicanos), the state-owned oil monopoly, owned and operated La Nogalera.The smell worsened by Sunday, April 19, when many residents complained to the Guadalajara Fire Department and the Intermunicipal Water and Sewer System--Guadalajara’s greater metropolitan sewer authority. By Tuesday, April 21, radio and local newspapers carried stories about the odors. Pemex and otehr governemtn officials recorded dangerously high gas levels in the sewer sysytem, but reassured residents that there was nothing to worry about. At about 10:06 a.m., April 22, the explosions began.

About 7 miles of sewer pipe exploded. When the city's main sewer pipe exploded, several city blocks were reduced to ravines containing 230,000 tons of rubble. The blast hurdled cars and busses in the air, some of which landed on nearby rooftops. Adults, children, and pets suddenly dropped out of site beneath the concrete rubble. The victims included a large number of children who had been playing on the street due to the Easter vacation. Much of the search and rescue activities were carried out by volunteers.

Pemex initially declared itself blameless for the blast, and instead blamed a local cooking oil for leaking hexane into the sewer system. However, on April 23, Pemex announced the discovery of a leak somewhere in one its gasoline pipe lines. By April 24, it had become clear that an extraordinary amount of gasoline had escaped. By one estimation, the underground soil was saturated with a meter-thick [three feet] blanket of the fuel covering 16 square blocks near the affected area.

After a long investigation, Mexico's Attorney General issued a report blaming Pemex for the explosion. Police indicted four Pemex executives, the mayor of  and other officials and charged them with negligent homicide in connection with the blast. Eventually, all those charged were cleared of any wrongdoing.

Sources

• Dugal, James, Guadalajara Gas Explosion Disaster, Disaster Recovery Journal, vol 5, no. 3, Accessed 25 August 2008.
• The Tech, Massachusetts Institute of Technology, Mexico Reels from Explosion, Friday, April 24, 1992
• Time Magazine, Pemex Is Blamed for The Sewer Explosion, May. 11, 1992.
• Suburban Emergency Management Project, The Guadalajara 1992 Sewer Gas Explosion Disaster, Accessed 25 August 2008.