1992 explosion in Guadalajara

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The 1992 explosion in Guadalajara, Mexico's second largest city, took place on April 22, 1992 in the downtown district of Analco. Numerous gasoline explosions in the sewer system over four hours destroyed kilometers of streets. Gante street was the most damaged. Officially, 206 people were killed, nearly 500 injured and 15,000 were left homeless. The estimated monetary damage ranges between $300 million and $1 billion. The affected area can be recognized by the more modern architecture in the areas that were destroyed.

Three days before the explosion, residents started complaining of a strong gasoline-like smell coming from the sewers. Some residents even found gasoline coming out of their water pipes. City workers were dispatched to check the sewers and found dangerously high levels of gasoline fumes. Unfortunately, the city mayor did not feel it was necessary to evacuate the city because he felt there was no risk for an explosion.

[edit] Aftermath

An investigation into the disaster found that there were two precipitating causes:

New water pipes, made of zinc-coated copper, were built too close to an existing steel gasoline pipeline. The underground humidity caused these metals to create an electrolytic reaction, which eventually caused the metal to corrode, creating a hole in the pipelines that caused gasoline to leak into the ground and into the main sewer pipe.

The sewer pipe was recently rebuilt into a U-shape so that the city could expand their underground railway system. Usually sewers are built in a slope so that gravity helps move waste along. In order to get the U-shape to work, an inverted siphon was placed so that fluids could be pushed against gravity. The design was flawed, however. While fluids were successfully pumped through, gases were not, and gasoline fumes would build up.

A small spark was all that was needed to ignite the dangerous gases. It is possible that city officials investigating the buildup of gasoline fumes actually set it off. Metal colliding with metal can cause sparks, such as when a manhole is dropped back into place.

In the aftermath, city officials and corporations pointed fingers at each other. Some people initially thought a cooking oil manufacturing company was leaking hexane, a flammable liquid similar to gasoline, into the sewers, but this was later found to be erroneous. Numerous arrests were made in an attempt to indict those responsible for the blasts. Ultimately, however, these people were released without charges.