Late Tuesday afternoon dozens of concerned neighbors called Hamblen County 911 to report the earth shaking and the sound of a large blast.
At first the the US Geological Survey reported there was no earthquake in the area.
That prompted local emergency management officials to spend Wednesday looking at other options.
10News spoke with TDEC (Tennessee Department of Environmental Conservation) who ruled out fracking or quarry activity.
Then, we checked with the University of Memphis Center for Earthquake Research and Information, sponsored by the USGS.
Geologist Gary Patterson went and pulled the records from sensors on Tuesday and says he could see activity consistent with an earthquake or quarry blasting.
Emergency Managment Agency Director Chris Bell says there was no licensed blasting in the Hamblen County area on Tuesday.
10News also confirmed with the area's only quarry, Vulcan Materials, that no blasting happened yesterday.
Patterson says the activity shows up over a large area with sensors reporting vibrations in Copper Ridge, Avondale Springs, Green Top, and Lonesome, VA.
He says the USGS doesn't have a lot of sensors in that area which may have resulted in the automated system's failure to report the activity.
Patterson says they need more time to investigate, but either an earthquake or quarry blasting could solve the 'Morristown Mystery.'
We talked to TDEC (Tennessee Department of Environmental Conservation) Spokeswoman Meg Lockhart said fracking wasn't to blame.
"We have zero oil or gas wells in Hamblen County, and no fracking that occur any closer than Claiborne or Campbell County," says Lockhart.
We also checked in with the only permitted mining operation in Hamblen County, according to Lockhart.
A manager for Vulcan Materials in Morristown says while they do occasionally "pull a shot" to extract rock from the ground, they did not do so on Tuesday.
Hamblen County EMA Director Chris Bell says they don't believe the shaking is attributable to any road work either. He says they've contacted TDOT and the contractors responsible for area sewer and road work and both confirmed they were not responsible for the shaking.
He says they're waiting on a written confirmation from geologists, but they also do not believe the area has any natural gas deposits which could be the culprit. He says they've also investigated the possibility of methane gas contributing to the quake phenomenon, and have ruled that out.
Do you have any theories? Post them in the comment section below, and we'll try to check them out.