CLINTONVILLE - The mysterious booms in Clinton appeared to have subsided overnight on Wednesday morning, but resumed again.
Police tell Newsradio 620 WTMJ's Jon Byman that they got about 30 calls between 5:00 p.m. and 11:17 p.m. Tuesday evening, but then the calls stopped.
According to what City Administrator Lisa Kuss told TODAY'S TMJ4's "Live at Daybreak," the six and a half hours of relative peace ended just before 5:00 a.m.
"At 10 minutes to five, we received about 28 calls again," said Kuss.
"People described the same thing, booming sounds, sort of explosions, rattling, vibrating in their houses. They described it as two or three booms."
The previous two nights, police were flooded with calls during the overnight hours as the mysterious booms continued into the night.
Despite a lot of effort over the past two days, no one has been able to say for sure what's causing the booms.
Kuss told "Live at Daybreak" that people there are becoming less frightened and more annoyed with the continual booms at night.
"In the beginning, when you have things that sounds like explosions, it's incredibly scary because people think of gas and things like that. Now that it's the third day, and we've confirmed that elevated gas levels don't exist, it's become frustration. People want to be able to sleep. It tends to happen more at night."
Still, one expert in Milwaukee says the abnormally warm weather could be to blame for the ground-shaking.
"There has been a lot of thawing underground," said George Stone, an instructor of Natural Science at Milwaukee Area Technical College in an interview with Newsradio 620 WTMJ's Erik Bilstad.
"(The shaking) could be related to ice melting and the release of the stress the ice creates."
Freezing and thawing cause potholes in the pavement every winter. The same rule could apply in this case, Stone theorized.
"We did have some cold weather earlier in the winter, which would've caused ice to freeze at considerable depth," he explained. "The warm weather could melt ice and relieve stress, causing movements and adjustments of some rock."
Water could seep deep into the ground via large quarries located in the area, he surmised.
Such theories haven't led anyone to a factual answer to the problem, and that also frustrates people in Clintonville.
"We certainly have a lot of geological explanations when people talk about the weather, the thawing, the exceptionally warm weather we're having so early," Kuss told "Live at Daybreak."
"The unfortunate thing is that when we talk to those geologists, no one can give you a definitive answer. They say, 'It doesn't sound like an earthquake.' Certainly, that's a possibility, but there's no way to confirm that. As it continues, it just keeps people's frustration levels up. It certainly makes sense, and it's sort of our top choice right now, some sort of natural phenomeon that's causing these noises."