INDIANAPOLIS (AP) — Investigators in the Indianapolis explosion that killed
two people and decimated a neighborhood believe natural gas was involved and
are focusing on appliances as they search for a cause, a city official said
Indianapolis Homeland Security Director Gary Coons made the announcement
after the National Transportation Safety Board said investigators had found
no leaks in the gas main or pipes leading into the house that exploded. The
explosion Saturday leveled two homes and left dozens more uninhabitable.
Coons said his “investigators believe natural gas is involved” and were
“recovering the appliances from destroyed homes to help determine the
“Based on the NTSB statement, our focus is on the houses and appliances,”
Coons said in a statement.
The blast showed some signs that aren’t typical of a natural gas explosion
caused by an appliance, experts said, but it still could have been tied to a
faulty furnace — if conditions were right.
An owner of the house believed to be at the center of the explosion has said
the home’s furnace had been having problems. But his estranged wife,
Monserrate Shirley, told The Associated Press on Tuesday that the thermostat
was replaced recently, correcting a problem heating the home. Shirley, who
lived in the house but wasn’t there during the explosion, said she had
smelled a strange odor outside before the blast, but didn’t know if it was
But experts said homeowners shouldn’t be worried that their furnaces are
about to explode.
John Erickson, vice president of the American Public Gas Association, said
it would take a far more serious malfunction than just a pilot light going
out. And forensic mechanical engineer Richard Schreiber, with Intertek AIM
in Sunnyvale, Calif., said it’s usually immediately evident whether a blast
was caused by natural gas.
Schreiber said that with explosions involving solids such as dynamite, the
center of the blast is tightly concentrated, creating a crater. Explosions
caused by flammable gas are typically spread out over a wide area, such as
throughout the interior of a building filled with leaking gas, he said.
“If the investigators don’t find a crater, that pretty much means it was
something other than a solid phase explosion,” he said, meaning it’s likely
to be a gas explosion. But he also said such investigations can still take
More than a dozen home explosions linked to natural gas have occurred in the
last two years. Many involved a single home, though more devastating blasts
tied to pipelines have been reported, including a 2011 explosion in
Allentown, Pa., that killed five people and a blast in 2010 in San Bruno,
Calif., that killed eight people and destroyed 38 homes. A gas leak in a
Colorado home last month sparked an explosion that sent five people to a
hospital and damaged several homes.
Erickson said more gas blasts are caused by appliances than by pipelines,
but even those are rare. Technological advances such as microprocessors and
the switch from pilot lights to electronic ignition have made appliances
safer, he said. Gas companies have been required since 1970 to add a
chemical that smells like rotten eggs to the odorless gas to make leaks
easier to detect.
Erickson also said a temperature sensor on furnaces is supposed to prevent a
gas valve from opening if the pilot light is out. But if that device were to
malfunction — or if a gas pipe in the house were to break — it could allow a
significant gas buildup and cause a big explosion, he said.
“To get a house to fill up with gas would take a pretty major leak. It would
be more than just a pilot light that went out and the gas continued to
flow,” Erickson said.
He said that between 60 and 80 cubic feet of natural gas could flow out of a
defective furnace or broken pipe every hour, rapidly filling a home or
The head of a company that does furnace repairs in Indianapolis said the
blast’s size made it unlikely that it had been caused by a leaking
“One hell of a lot of gas had to be leaking out ... and that’s typically not
symptomatic of a furnace problem,” said Sergei Traycoff, president of Bolls
Heating and Cooling. “I’ve never heard of one causing this big a blast.”
Consumers can best protect themselves by having their furnaces inspected
regularly, he said.
Erickson said it was odd that the blast apparently flattened two homes side
by side. Generally, if a house explodes, it will knock out the wall of the
home next door, but not level it, he said. For that to occur, both homes
would virtually have to have gas leaks that ignited at the same time, he
Schreiber added that gas explosions create an intense wave of heat that can
ignite surrounding homes.
“It goes very quickly. It’s just a ‘whoosh,’ you know, like if you have a
gas stove or a grill where it doesn’t ignite immediately and there is a
whoosh sound. That’s kind of what happens here, but at a much, much greater
level. It’s a quick event, not a lingering thing.”
The NTSB said the natural gas lines inside the house would be under the
oversight of the utility or the state. Citizens Energy spokeswoman Sarah
Holsapple said the utility had found no leaks in its underground facilities
in the neighborhood; the Indiana Utility Regulatory Commission had no
Glenn Olvey, 52, isn’t sure what caused the blast that wrecked his home and
vehicles. But he knows his family is fortunate to be alive. The blast hurled
Olvey several feet and trapped him, his wife and one of their two teenage
daughters when their roof collapsed.
“I have been through car accidents, I’ve been through motorcycle accidents,
I’ve been through tornadoes. I have never, never had anything like that,” he
Olvey said he and his wife, Gloria, have struggled knowing that the
explosion killed Jennifer and John Longworth, just two doors down.
“We’re alive for a reason,” he said. “What it is, I don’t know.”