It was a startling, slow-motion upheaval -- the pavement on Dearborn Street steadily rising, knocking a building several feet off its foundation, stopping after about half an hour with a cracked, buckled road surface eight feet higher than it started.
The following day, experts were left scratching their heads.
At a news conference at the site in southwest Detroit, city and utility officials could only speculate on what happened.
"As we know, there was no explosion here, that is the main point we want to get out," said Hakim Berry, chief operating officer for the city of Detroit. "There was a slow growth of something that happened underneath."
Officials have yet to explore the hill or what may be in it and won't be able to until the demolition of an affected business, Stash Detroit, a cannabis dispensary at the intersection of West Fort and Dearborn streets. The building shifted a few feet off the ground when the road buckled, but employees were able to evacuate safely.
... "We've talked with a lot of experts and they all have said they've never seen anything like this," Berry said, "so it is very intriguing to us and we can't wait to get in there to see what caused this."
Although there was no explosion, there had been a strong natural gas smell in the area for some time, and a leaking water main into the basement of the dispensary, leading to speculation that the two are connected in some way.
DTE will first seal the gas leak, then the mound will be excavated to find the cause.