UPDATE: On Friday, the Orange County government said the U.S. Geological Survey completed a review of the area and determined the loud noise ultimately was a small earthquake.

Despite the USGS not initially having an earthquake among its data on Thursday, a release from the county said the federal department is confirming the earthquake was 2.2 magnitude that happened about 3.3 miles beneath the surface. The center of the quake was 2.6 miles southwest of Hillsborough and happened at 11:49 a.m. Thomas Pratt, a research geophysicist with the USGS, confirmed to Chapelboro on Friday that the department’s algorithms picked up a disturbance at that time — but it initially did not report the as an earthquake because it assumed the nearby rock quarry in Hillsborough had conducted a blast.

The determination came after local emergency services and law enforcement searched Thursday for potential causes of what was described as a “thunderous boom.” Orange County officials determined by checking with nearby Air Force officials that no scheduled flights took place near Hillsborough on Thursday morning that would’ve caused a sonic boom. An Air Force public affairs official also told emergency services that no Navy flights were conducted either, eliminating further options after the Orange County Sheriff’s Office determined it was not an explosion at the nearby rock quarry, I-40 construction site, or Collins Ridge construction site. 

“Given the heightened state of security, it was important for us to assess and attempt to determine the cause,” Orange County Emergency Services Director Kirby Saunders said on Friday in the county’s release. “We were able to quickly rule out any threats/risk to the safety of our community.”

The U.S. Geological Survey’s page marking the earthquake in Hillsborough can be found here.

Below is the original story published on Thursday, October 19 in the hours after the earthquake.


A tremor and loud noise briefly shook the town of Hillsborough on Thursday, leaving people wondering where it came from and whether people were okay.

Shortly before 12 p.m., community members reported to Chapelboro feeling a shaking of the ground and buildings for a few seconds — with others adding that it was preceded by a loud boom.

Both the Orange County and Hillsborough local governments shared posts saying their authorities are investigating the cause of the noise.

While the description of the event seems similar to an earthquake, the U.S. Geological Survey did not report any earthquake in North Carolina at that time on Thursday. Duke Energy was not reporting any power outages in the 12 p.m. hour either.

The Orange County Sheriff’s Office said it is looking into the source of the tremor and it was receiving many calls from people reporting the noise and shaking. But Director of Public Information Alicia Stemper said the office had not received any calls of injuries nor property damage in the first half-hour after the event.

The Orange County courthouse briefly evacuated its staff following the tremor, but returned to the building a few minutes later and is continuing normal operations. Orange County Clerk of Court Mark Kleinschmidt expressed this in a post on X, formerly known as Twitter.

While the incident was felt at Orange County Schools campuses, the district is not changing its plans for the day. Kevin Smith, the chief communications officer for the district, confirmed to Chapelboro that all operations for its schools would continue like normal for the rest of Thursday.


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