As families mourn the deaths of their loved ones from an explosion at a Mexican resort, the focus of the investigation looks not only deep inside the grounds of the hotel, but also to a place not far away: a swamp.
The blast Sunday at the Grand Riviera Princess hotel in Playa del Carmen, south of Cancun, killed five Canadians, including a nine-year-old boy. It left a crater about a metre deep in one of the buildings and hurled glass and other debris onto the lawn.
Authorities in Mexico were quick to point out that the cause could be methane and other gases from a nearby swamp drifting below the hotel, building up to high levels and then igniting from a spark. The hotel was partly built on top of a cave.
The investigation aims to determine whether the building, which sat on a concrete pad near the beach, was properly constructed.
Bruce Anderson, a professor of civil engineering at Queen's University, said that in order for an explosion like the one at the resort to occur, there would have to be a huge containment of methane gas and it would need an ignition source such as a cigarette or an electrical spark.
"It sounds to me like there potentially was seepage of that vapour into some kind of contained environment, maybe under the concrete floor of the resort. And at a certain point, you have enough pressure in the system and with the right ignition source, you have the explosion hazard," Prof. Anderson said.
He said that it's impossible to predict when an explosion could occur, because methane gas is odourless. "But I think if you're building next to a swamp and the swamp is known to be producing gas, then it's something you might want to look out for," he said, adding that there should be some form of venting for the gas.
"You're putting a very heavy surface on a formerly open field, for example. Or they may have drained some of the swamp to put the hotel on, and then you're compacting and really just creating the conditions to pressurize that gas."
The explanation provided by Mexican authorities, however, has left some experts doubting its validity. Western Kentucky University geologist Lee Florea said he has never heard of an explosion in the area because of a buildup of gases. "It's not every day that you hear of these types of explosions, and if this were natural, it might be more frequent than that, considering the pace of development that has occurred in regions like that near the coastline," he said.
With a report from The Canadian Press