The explosions moved through the sewer system like a fuse burning through a city. The first two struck at 10:05 a.m. -- one at Calzada Independencia and Aldama Street, the second at Gante and 20 de Noviembre. Three minutes later, a third blast hurled a city bus into the air at Gante and Nicolas Bravo. By 10:15, factory workers along Gonzalez Gallo Avenue were fleeing on foot as rescue teams scrambled toward the growing destruction. The fifth explosion hit at 10:23, the sixth at 10:31. The seventh came at 10:43 on Gante and Silverio Garcia. After the eighth blast at 11:02, authorities began mass evacuations of entire neighborhoods -- Atlas, Alamo Industrial, El Rosario, Quinta Velarde, Fraccionamiento Revolucion, and the center of Tlaquepaque municipality. The final two explosions, at 11:16, struck along the river-named streets: Rio Alamos and Rio Pecos, Gonzalez Gallo and Rio Suchiate. That afternoon, terrified residents across the Guadalajara metropolitan area pried open manholes to vent any remaining gas.

Investigators found two causes working in concert. First, new zinc-coated iron water pipes had been installed too close to an existing steel gasoline pipeline. Underground moisture created an electrolytic reaction between the metals -- essentially, the same chemistry that powers a zinc-carbon battery -- which corroded a hole in the steel pipe. Gasoline leaked steadily into the ground and into the main sewer line. The second cause was architectural. The city had recently rebuilt the sewer into a U-shape to accommodate its expanding metro rail system. Conventional sewers slope downward, relying on gravity. The redesigned section used an inverted siphon to push fluids under the metro tunnel. But inverted siphons require uniform fluid density to function. Water, being heavier, passed through. Gasoline, being lighter, was trapped upstream. As liquid fuel accumulated, its vapors spread eastward through the sewer pipes, filling miles of underground passages with an explosive atmosphere. The manhole covers that bounced on the morning of April 22 were the last warning.

In the aftermath, every institution pointed at the others. Initial suspicion fell on a cooking oil manufacturer thought to be leaking hexane into the sewers, but that theory was discarded. Four officials from Pemex, Mexico's state oil company, were indicted on negligence charges. They were eventually cleared. No one was ever convicted for a disaster that destroyed neighborhoods, killed hundreds, and left between 500 and 600 people unaccounted for. The lack of accountability became its own wound -- one that survivors carried for decades alongside their physical injuries and the loss of their homes, their health, and their families.

Among the survivors was Lilia Ruiz Chavez, who lost her leg and her home in the explosions. She founded La Asociacion 22 de Abril en Guadalajara, a group of 80 members who spent more than two decades demanding accountability and compensation. The victims had lost not only loved ones but their ability to work, to pay for medical treatment, to rebuild. Chavez and her members pressed Pemex relentlessly. After years of advocacy, Pemex agreed to a payment of MX$40 million to the group -- while insisting the payment was a donation, not an admission of responsibility. For Chavez, the money could not restore what was taken. But the fight itself became a testament to what the people of Analco refused to accept: that a preventable catastrophe, announced by four days of gasoline fumes and dismissed by a mayor who saw no risk, could simply be forgotten.