UK geologic hazards section head Zhenming Wang told the Associated Press the quake, which had its epicenter about 10 miles from the surface and deep coal mine-infused area of Whitesburg, occurred about 12 miles below the surface.
Earlier reports had put the depth at less than a mile.
Wang said the extensive depth of the quake was far too deep for underground mining to have been a factor.
University of Memphis Center for Earthquake Research and Information research scientist Stephen Horton said: “If the earthquake had been close to the surface, then we might think it was mining-related. The depth is the give-away, really.”
The experts also ruled out hydraulic fracturing as a factor.
Wang said he was not aware of any fraccing operations in the area where the quake occurred.
The tremor came from the Eastern Tennessee Seismic Zone and, while earthquakes in the eastern Kentucky coalfields are rare, the zone does record a four-magnitude event about every five to 10 years.
The Saturday event, which caused minor damage, lasted for about 15 seconds.
Residents in nearby Virginia, West Virginia, Tennessee, North Carolina, South Carolina, Indiana, Ohio and Georgia also reported feeling the quake.
An aftershock measuring 2.5 magnitude followed about 90 minutes later near Hazard.
