For five years, Dan Marries, an evening news anchor for KOLD News 13, has been researching the loud booms heard and felt across the Tucson area. He says the glass doors at his home in Tucson shake.

 Mamta Popat, Arizona Daily Star

Most journalists live for an exclusive, for breaking a big story and staying ahead of the competition.

Dan Marries has been ahead all the way on this story, but it’s been kind of lonely.

The story just goes on and on, regularly affecting people around the Tucson area, but he has been the only one focused on it.

Marries, evening news anchor at KOLD Channel 13, has taken to calling the phenomenon “mystery booms.” He’s reported on them repeatedly since 2017.

People around the Tucson area hear these booms, but they seem to be especially prevalent on the west side of the metro area. People feel a rumble in the ground and hear a boom. The house may shake briefly. And that’s about it.

The last one Marries did a story on was Jan. 22; another took place just this past Thursday.

“You feel it rumble. It feels like it’s coming from the ground,” said Ernesto Bonillas, a Green Valley resident.

“Those booms are nothing new,” he added. “Today was stronger than normal.”

Bonillas was one of dozens who commented on Marries’ Facebook post about the latest mystery boom. Another, Michelle Ansbach, lives on the southeast side.

She told me via Facebook message she’s felt occasional booms and rumbles for years.

“It sounds and feels like it is coming from under the ground. I’ve experienced earthquakes while living in Washington state and it isn’t an earthquake. I also lived across from the base here for 3 years, still not the same. Definitely not sonic booms.”

‘Quit asking questions’

People give varying descriptions, said Marries. As he spoke, he was standing on his northwest-side patio, where he’s watched his glass doors shake during the booms.

“You know, earthquake, sonic boom, truck driving by, something falling on the house, ‘I thought something hit my house,’” Marries said, rattling off the explanations he hears from the public. “One of the people said ‘I felt like a car ran into my house.’ That’s how much force some of these have.

“What I have personally felt — you can kind of feel a rumble come through. It’s like a wave,” he said.

He doesn’t discount sonic booms, which are perhaps the most likely explanation, but Marries, who comes from a family full of pilots, isn’t convinced of that, either.

Security cameras belonging to Phil and Arty Williams recorded the sound of one of Tucson's "mystery booms" at their Picture Rocks home in 2019. 

“You could describe these as a sonic boom, but when you feel the rumble in the ground, that’s what makes it different for me,” he said. “Obviously, sonic booms come from the air. These mystery booms, rumbles or whatever you call them seem to come from the ground.”

When Marries reports the booms, people of course chime in with their own theories. One is that it has to do with the geological effects of the water table dropping. Others?

“Underground tunneling for secret government operations, secret military bases. That’s a pretty popular one,” he recalled. “Then there’s the people who say ‘It’s a sonic boom, idiot. Quit asking questions.’ You tell a reporter to stop asking questions. Come on — that’s what I do for a living.”

Marries has even dug into the journals of William Clark, who reported unexplained booms in the Lewis & Clark expedition, and checked out reports of the “Seneca Guns“ — a similar phenomenon reported on the East Coast.

Seismic station detects them

It’s clear something real is happening around here. Not only have hundreds of people from around the Tucson area responded to Marries’ Facebook posts about the mystery booms, reporting what they felt at the same time, but geologists regularly detect them on a local seismometer.

A pair of these mystery booms occurred Thursday, most people noticing them at about 11:08 a.m. When Marries asked University of Arizona geosciences professor Susan Beck about it, she checked the seismometer, and there were the signals. Two occurrences at 11:08.

Tucsonans noticed the latest "mystery booms" about 11:08 a.m. Thursday. A local seismological station detected the rumbles at the same that residents felt them, said UA professor of geosciences Susan Beck. (Arrow added by the Star.)

This happens all the time. In fact, Beck told me she’s seen similar reports occasionally since she arrived in Tucson in 1990. The seismological station generally shows something happened, but it’s not clear what.

“Every time I’ve looked at these over the years, they’re not earthquakes,” Beck said. “The problem is we only have one seismic station. I can’t tell you where they’re coming from.”

So they remain a mystery.

This has been a bit frustrating to Marries. Every time he feels, hears, or hears of one of the mystery booms, he posts about it on Facebook. Inevitably, he gets dozens of replies from people like Bonillas and Ansbach, reporting familiar booms, rumbles and rolls.

Then Marries goes down his list. He calls Davis-Monthan Air Force Base. He calls Luke Air Force Base near Phoenix. He calls Asarco to see if they’ve been using explosives at the mines.

“Out of all these incidents, they’ve never been doing mining explosions that day,” he said. “Out of all these years, there’s been one sonic boom reported on the same day, but it wasn’t at the same time.”

Seismic network would be helpful

Marries also calls Beck or other members of the UA’s geosciences department, who typically find that something registered on their seismometer.

Beck doesn’t know what explains them all. She’s discounted earthquakes because of the seismological signature and the sound. She also doubts mining explosions, because of the distance they seem to travel.

Beck leans toward sonic booms as the explanation. With Southern Arizona’s dry climate and steep topography, jets could break the sound barrier a long ways away, with the effects rippling toward us probably from the west.

“I think it’s an atmospheric disturbance, most likely a sonic boom of some sort that couples into the ground as it comes across,” she said.

A few steps could start solving the mystery. Simple ones include mapping where people feel them and registering the times. Marries has got reports from SaddleBrooke to Sierra Vista, and lately they usually happen between late morning and midafternoon.

The most important step, though, would be to station seismometers around the Tucson valley, Beck said. That would allow them to capture the direction and speed of the booms. Then the source could be narrowed down. But it would take maybe 10 to 12 of them, and good ones are not cheap.

Marries plans to persist on the story, his unwanted exclusive.

“I’m just so curious what’s causing it,” he said. “But after so many years, I’m still at square one. I’m no closer to figuring out what it is than I was at the beginning.”

Become a #ThisIsTucson member! Your contribution helps our team bring you stories that keep you connected to the community. Become a member today.

Contact columnist Tim Steller at tsteller@tucson.com or 520-807-7789. On Twitter: @senyorreporter