A lot of Tri-Staters are asking the same question Wednesday night as they were Tuesday- what are those boom sounds they hear and feel late at night?
Wednesday night, we can help eliminate some of the theories floating around.
It's been referred to as everything from a semi truck, to an earthquake, and even a possible explosion.
14 News sat down with USI Professor of Geology, Paul Doss. Doss has been looking at the seismomitor for the past several days.
"Earthquake energy is an acoustic energy, but it would not be transmitted out of the crust and into the atmosphere. When I look over the last few days, at these times, nothing, nothing," Doss said.
If it's not underground, perhaps the sounds originate in the sky. A sonic boom from military aircrafts? The Indiana Air Corp says that's also not possible.
"We didn't have any training events. The State of Indiana and the Air Guard, they have A10s based out of Ft. Wayne and they're not capable of executing that type of activity," said Lt. Mark Weaver.
Some residents say the sounds are coming from space. Maybe meteors which would certainly be strong enough to shake homes. But Professor Jeff Braun says the lack of visible evidence quickly disproves this theory.
"Meteors can cause sonic booms when they come in, but almost always they're accompanied by a visible fireball," Braun told 14 News.
Without that bright flame in the sky, no meteor crashing into your backyard.
Some people say tannerite, an exploding target used at outdoor gun ranges have a loud boom sound. But local gun store owners say it doesn't pack a punch powerful enough to be heard in several different parts of the city, let alone across the nation.
"At this point, nobody seems to know. The geologists say it's not in the ground, the Air Force says it's not in the air, the astronomers say it's not from space, so we're running out of options," Braun said.