COLUMBIA, S.C. (WCBD) — South Carolina’s lead health agency on Thursday addressed some questions surrounding an uptick in recent earthquakes in the midlands and whether they are being caused by mines.

A 3.5 magnitude earthquake was recorded near Elgin, South Carolina the morning of June 29 — it was followed by a series of aftershocks in the area, including a 3.6 magnitude earthquake that rattled much of the region around 7:00 p.m. that same evening.

A 2.32 magnitude earthquake was recorded around midnight on Thursday, with two additional aftershocks in the morning, several hours apart.

The South Carolina Department of Health and Environmental Control said permitted mine sites in the area are surface pits, the majority of which are 30 feet or less in-depth.

“Their shallowness would not be expected to contribute to seismic activity, especially with recent earthquakes being recorded at 6,336 to 12,672 feet deep, according to the United States Geological Survey,” the agency said.

Health officials said even the deepest permitted mine site — 900 feet — does not come close to the depth in which the earthquakes were reported and is located 75 miles away from Elgin.