There have been no small number of rather bizarre accidents from humans humaning, everything from that time the City of Boston almost literally drowned in molasses to how humans drilling a 14 inch hole accidentally created a 1,300-foot deep saltwater lake out of a formerly 10-Foot deep freshwater one (more on this hilarious event in the Bonus Facts later.) But yet another curious such event was that time a rather large portion of the Reforma district of Guadalajara, Mexico just up and exploded one day for reasons… This is the story of one of the greatest urban disasters you’ve never heard of.

Guadalajara, located 300 kilometres northwest of Mexico City, is the capital of Jalisco state and, with a population of 3 million, the second-largest city in Mexico after the capital. The morning of April 22, 1992 was just like any other in Guadalajara, the largely Catholic population having just celebrated Easter. All was normal – all, that is, except for the smell. Four days before, residents of the Reforma district had noticed a strong gasoline-like odour- mainly those along Gante Street. At first, people ignored the smell, attributing it to annual cleaning at the nearby Nogalera gasoline storage facility. One of nearly 40 factories and storage facilities in the industrial, working-class neighbourhood Nogalera was owned by Petróleos Mexicanos or Pemex, Mexico’s national petroleum monopoly. Yet as days passed, the smell got progressively worse, causing eye and lung irritation and severe nausea. Residents even reported gasoline fumes streaming out of faucets.

In response to complaints, on Tuesday, April 21, Jalisco State Governor Guillermo Vidaurri cordoned off large sections of Reforma while dozens of members of the Guadalajara Fire Department, the State Civil Defense Unit, the local police, and the Intermunicipal Water and Sewer System or SIAPA descended on the district to investigate. Sampling of the water and air throughout the district soon revealed the source of the smell to be the industrial solvent Hexane. More alarmingly, vapour concentrations in many of the sewer lines had reached 100% explosivity – meaning that the slightest spark could potentially set off a massive explosion. Suspicion immediately turned to a nearby plant operated by the company La Central S.A., which used Hexane to extract cooking oil from seeds. Though an inspection of the plant revealed no solvent leaks, Jesus Doria, a member of La Central’s board, immediately ordered the facility shut down as a precaution. Meanwhile, the fire department opened manhole covers and flushed drains across the district in order to let the Hexane vapours dissipate. By 3:30 AM on April 22, explosivity levels had dropped from 100 to only 15%. Believing the problem had been solved, the firefighters and other government workers returned home.

By 9 o’clock, however, explosivity levels had risen back to 100%, and members of SIAPA met with Governor Vidaurri and Guadalajara Mayor Enrique Dau Flores to discuss evacuating residents from the Reforma district. These officials, however, chose to ignore their warnings, and throughout the morning firefighters and SIAPA workers continued to assure Reforma residents that there was nothing to worry about.

Then, just past 10 o’clock in the morning, all hell broke loose.

28-year old Alberto Pulido was driving to work down Violeta Street when the first explosion occurred. He watched in horror as, like in a scene from a supernatural horror film, the ground suddenly opened up beneath him:

“I thought a car had hit me from behind, and then I saw the earth was opening up and my car was sinking. I prayed to God. I thought I was going to die.”

Miraculously, despite having a semitrailer roll over onto his car, Pulido escaped unscathed.

Meanwhile, Gonzalez Cervantes was at home watching television when the ground began to shake beneath him:

“There was a huge boom. I came outside, and there were cars on roofs and clouds of dust everywhere. People were crying. They were hysterical. I’ve never seen anything like it.”

The first explosion took place around 10:06 near the intersection of Gante and 20 de Noviembre. This was followed barely 5 minutes later by another explosion near Violeta. Surging south along the sewer main that ran beneath Gante street, three more major explosions followed, the last occurring around 2:20 PM near the intersection of Rio Alamo and Rio La Barco-Gonzalez Gallo. According to disaster sociologist Benigno Aguirre, residents had almost no warning of the surreal wave of destruction speeding towards them:

“The only indication of warning [was]…people looking down the streets and seeing a rapidly disintegrating landscape advance towards them. Those who survived turned away from the center of the street where the drainage pipe that blew up was located.”

The five explosions demolished or damaged more than 1,500 homes and businesses and reduced eight kilometres of city streets to gaping ravines 5 metres deep and choked with 230,000 tons of rubble. Hundreds of cars, buses, and other vehicles were swallowed up by the ground, while several were struck by flying manholes and launched into the air, sometimes landing upside down atop buildings. Inside at least one flying car was a newborn infant, who miraculously survived. When the smoke finally cleared over 200 people lay dead, 1,800 injured, and 500 trapped beneath the rubble. A large proportion of the victims were children, home from school for the Easter break. Wednesday was also market day in La Reforma, and thousands had been out on the streets when they collapsed beneath them. A further 25,000 people had to be evacuated from the area, while the disaster inflicted an estimated $3 billion in physical damage.

As first responders, Red Cross personnel, and civilian volunteers raced to rescue survivors from the rubble, firefighters re-opened manhole covers and pumped soapy water into the sewers to neutralize any remaining fumes. Later, trenches and pumping wells were dug to drain off liquid gasoline and prevent it from contaminating the aquifer beneath the city. Despite these precautions, however, a further two explosions rocked the neighbourhood early the following morning. The sheer number of victims soon overwhelmed local hospitals and clinics, so temporary accommodations for the injured and homeless were set up in two local sports stadiums, while makeshift morgues were established in gymnasiums and other public buildings.

Meanwhile, an investigation as to the causes of the explosions began – as did the inevitable finger-pointing. Pemex pushed the initial theory that the solvent leak had come from the La Central oilseed facility. However, the plant had been shut down for the Easter weekend and had not suffered any leaks in its Hexane storage tanks. Furthermore, the capacity of said tanks was far below that needed to fuel an explosion the size of the Guadalajara disaster. Finally, investigators determined that the explosions had been caused not by pure Hexane but rather ordinary gasoline – of which Hexane is only one component. Suspicion thus shifted to Pemex’s Nogalera gasoline storage facility. The investigation soon revealed that 8 days before the disaster, Nogalera had registered a pressure drop in a pipeline carrying gasoline from a refinery in Salamanca to the Guadalajara depot, indicating a rupture in the pipe. This rupture was quickly traced to a spot less than 1 kilometres from the depot. Here, a section of zinc-plated copper pipe from the municipal water distribution system had been laid close to the steel gasoline pipe in violation of local building standards. The two dissimilar metals in close proximity created an electrolytic reaction, causing the gasoline pipe to corrode through and leak into the ground, with the fuel eventually finding its way into the municipal drainage system. The poor design of the sewer system itself also contributed to the disaster. A new line of the subway system had recently been installed, requiring the main sewer to be diverted around it. City engineers accomplished this by building a U-shaped inverted siphon – rather like the S-bend in a toilet – under the subway line. However, siphons like this only work with fluids of uniform consistency. With a mixture of different fluids – like water and gasoline – only the densest fluid passes through the siphon, leaving the lighter fluids trapped upstream. This caused gasoline fumes to gradually accumulate in the sewer line, creating the perfect conditions for an explosion. What exactly set off the vapours is unknown, though given the high explosivity measured in the sewers just before the disaster, it could have been almost anything, from two pieces of metal striking each other and creating a spark to someone carelessly tossing a cigarette butt down a manhole.

In light of these revelations, several Pemex executives were arrested and interrogated in an attempt to determine who bore responsibility for the disaster. Disturbingly, this was not the first time fuel had leaked from the Nogalera facility and ignited, a similar incident having occurred less than a year before in October 1991. Thankfully, only a few manhole covers were blown off and nobody was hurt. Nor was this the first time negligence on Pemex’s part had resulted in mass casualties. In the early morning hours of November 19, 1984, a ruptured pipe at the company’s San Juan Ixhuatepec storage facility caused over 10,000 cubic metres of liquefied petroleum gas to go up in flames, triggering a series of massive explosions that destroyed 150 homes, killed 450 people and severely injured 5,000 more. It was one of the largest industrial disasters in history and one of the most powerful manmade explosions ever recorded, the shockwave from the blast registering 0.5 on the Richter scale.

But the irresponsible behaviour doesn’t stop there. In June 3, 1979, Ixtoc I, an exploratory well drilled by the Pemex in the Gulf of Mexico, blew out and released 3 million barrels of crude oil into the ocean – the largest oil spill up to that point and the second largest in history after the 2010 Deepwater Horizon disaster. And if that weren’t bad enough, recent investigations have determined that over 95% of the industrial wastes produced by Pemex facilities in Mexico City are dumped directly into the municipal wastewater system.

Yet despite this long and sordid history, Pemex has almost never faced justice for its negligence. The 1992 Guadalajara explosions were no exception, with all of the arrested executives being cleared of all charges. Why? Allegedly because Pemex is, quite simply, too large and powerful to touch. With assets valued at over $100 billion, Pemex is the single wealthiest entity in Mexico and its largest source of public funds, contributing a whopping 40% of the Federal Government’s annual revenue. Unsurprisingly, such vast fiscal power allegedly breeds rampant corruption, allowing Pemex to operate as an independent state-within-a-state. Indeed, about the only person indicted for their part in the disaster was Guadalajara Mayor Enrique Dau Flores, who subsequently resigned from office. Meanwhile Pemex quietly funded the reconstruction of the shattered neighbourhoods and established a $40 million fund to help the victims of the disaster. However, the company has vehemently insisted that this is a donation and in no way implies responsibility for the incident.

But given the sheer extent of the devastation, even $40 million doesn’t go very far, and in the wake of the tragedy survivors formed a group called La Asociación 22 de Abril en Guadalajara to fight for fair compensation for the injuries inflicted and the lives, homes, and livelihoods destroyed by the 1992 explosions. 30 years on from the disaster, the streets, buildings and sewers of Guadalajara may have been rebuilt, but the scars of the horrific day still run deep.

Bonus Fact:

Going back to the story of how drilling a relatively small hole set off a sequence of events creating a giant salt water lake out of a small freshwater one- Lake Peigneur is located in Louisiana near the Gulf of Mexico. Before 1980, it was an approximately 10-foot deep fresh water lake with an island in the middle. Next to it, and partially under it, Diamond Crystal Salt Company maintained a salt mine, with salt being mined near the lake since 1919.

Around large underground salt domes, you can often find oil. As explained by one Dr. Whitney J. Autin, “…salt moves upwards and it pierces through surrounding strata… and this piercing produces faults and folds within the surrounding sediments producing an ideal mechanism to trap oil.”

As such, Texaco was doing some drilling in the lake. On November 20, 1980, crews on the oil rig in the lake ran into a problem. At just over 1,200 feet, their drill seized up. Not a major problem normally, they worked to get it loose. In the process, they heard several loud pops then the oil rig tilted like it was going to collapse. The men got off the rig and to shore as quickly as possible. Not a moment too soon. Just 19 minutes after their drill had seized up, they watched from the shore as the huge platform (150 feet tall) overturn and sank into the 10 foot deep lake…

Next, the astounded drillers watched as a whirlpool slowly formed, soon reaching a quarter mile wide and centered over the site of the oil drilling.

Whoopsadoodle.

At the same time the oil workers were watching their $5 million drilling rig disappear into the lake, workers in the salt mines below the lake noticed something was wrong as well; a stream of water was found flowing along the floor of the mine shaft at about the 1,300 foot level of the mine, which went down to about 1,500 feet at its deepest. As water wasn’t supposed to be in the mine, the evacuation alarm was raised. Foreman Randy LaSalle then drove a cart around to the regions of the mine where the alarm signal could not be seen, making sure everyone knew about the evacuation. By the time those from the deepest areas of the mine made it to the elevator, they encountered knee-deep water. Despite the fact that the mine was rapidly filling with water and the exit elevator could only take up to eight people at a time, all 55 miners were evacuated successfully.

It wasn’t clear to the miners what had happened at the time, but from the evidence at hand, the theory is that the drilling crew miscalculated their location and instead of being several hundred feet from the salt mine, they had instead been directly over a portion of it and penetrated the salt dome. The initial hole resulting from this mistake was only 14 inches wide, but water spraying in at extremely high pressure quickly widened the hole. The water also dissolved the salt pillars that supported the ceiling of the mine, causing the shafts to collapse.

The widening of the hole and the collapse of the mine gave strength to the whirlpool on the surface of the lake, which caused major damage. Docks, another drilling platform, a 70 acre island in the middle of the lake, eleven barges, vehicles, trees and a parking lot near the lake were all sucked into the mine below. The pull of the whirlpool was so strong that it reversed the flow of the 12-mile-long Delcambre Canal that drained the lake into the Gulf of Mexico.

Three hours after the first signs of trouble, the three to four billion gallons of water that had made up the lake were almost all gone, having dropped into the mine below, leaving a gaping crater. The backward-flowing canal formed a 160 foot waterfall that gradually refilled the lake, this time with salt water from the Gulf.

The 10-foot deep freshwater lake was now a saltwater one, approximately 1,300 foot-deep in a good sized portion of it.

Amazingly, there were no deaths or serious human injuries as a result of the disaster, though the ecosystem of the lake was forever changed. Further, three dogs died in the event. Many lawsuits were filed, all settled out-of-court, costing Texaco about $45 million in damages, with about $32 million of that going to Diamond Crystal.