EVANSVILLE, Ind. (WFIE) - Doctor Scott Davis is a Combustion Systems Expert and CEO of Gexcon.

He’s a seasoned explosion investigator, and he says when you investigate an explosion like the one on Weinbach Avenue, you’ve got to start ruling things out before you can land on a cause.

[Previous Story: Weinbach Ave. opened near explosion site]

After seeing video and our coverage of the incident, he has an educated guess.

“I would just say it was a decent fuel-air mixture,” Davis said. “I would say the fuel-air mixture was on the reactive part. I mean it could be propane that could do the same thing, natural gas could do the same, ethanol, gasoline,” Davis continued. “You just pick and you name it, you can put it in that phase, and the energy content of all those fuels is very similar.”

When it comes to helping investigators come to that conclusion Davis says the size and destruction of the blast plays a role.

“A pilot leak in your house won’t do it, so one outside is obviously not going to do it either. So, you’re not talking about these small leaks, you’re talking about something very significant that could migrate into the home,” Davis said, “if you’re looking at the gas system in the home, it’d have to be some kind of catastrophic failure or something opening inside of the home as well.”

He says an investigation into an incident like this could take weeks, or even months, and it’s not unheard of for the end result to be “undetermined.”

He also says this has the markings of a fuel-air explosion, but it would take a serious amount of fuel, whether that be natural gas, propane, ethanol or something else entirely to create a scene of this magnitude.

From Davis’ observation, he estimated that it would have to be an entire floor of a house. For instance, a basement, main floor or upstairs of a home that was entirely full of gas.

“With the level that I saw here, you’re probably talking at least a full volume layer. Whether it’s basement and partially upstairs, or a little bit more of the upstairs, you’re talking a significant volume,” says Davis.

Indiana State Fire Marshal’s as well as the Evansville Fire Department confirmed that there’s no specific timeline in place.

Our 14 News team looked into the layout of utility pipes in the area, among other things concerning this case. A Freedom of Information Act request was also sent to CenterPoint energy for access to some of those answers, but we were denied.

CenterPoint cited that they are a private company and don’t have to abide by those laws.

Expert: Cause of fatal Evansville explosion possibly related to fuel-air mixture