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 time.
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.