Hillsborough experiences "very, very rare" 2.2 magnitude earthquake

Last week, Mark Kleinschmidt was getting a burger at The Colonial Inn in Hillsborough when he heard a loud boom and felt the restaurant shake.

Before he knew the shake was an earthquake, Kleinschmidt, the Orange County clerk of superior court, posted on X voicing concerns shared by him and those around him. In his post, Kleinschmidt said he'd heard rumors that the noise came from a possible plane crash or explosion.

“It was just a huge mystery,” he said.

Kleinschmidt said about 30 minutes after the earthquake, he got an email from Orange County Emergency Services informing him that concerns like explosions, building failures and extraterrestrial landings had been ruled out.

The U.S. Geological Survey, the agency in charge of monitoring natural hazards, concluded the noise was the result of an earthquake with a 2.2 magnitude and a shallow depth of three miles on Oct. 20, the day after the event.

Sarah Pickhardt, the Orange County Emergency Management Division chief, said she initially thought a crash occurred nearby, but after calls began coming into the 911 center, she realized it was something more.

“That for us was a trigger of something has happened, and it wasn’t something that happened on our property, this was something that was impacting the Town as well,” she said.

Pickhardt said the division received calls from the Hillsborough area after the earthquake, although she said none of these reports were about damage or requesting assistance.

Pickhardt said the Emergency Operations Center responded to the earthquake by ruling out potential causes. She said the center’s partners used drones, checked with the rock quarry and communicated with state and federal agencies. 

“We ruled out anything that could have been a public safety threat, a public safety risk — and we were able to do that fairly quickly,” she said.

Prior to ruling that it was an earthquake, Pickhardt said the USGS received a report of seismic activity near the Hillsborough rock quarry. She said her team worked alongside the USGS to determine that an earthquake had occurred. 

Pickhardt said the small size of the earthquake caused a delay in the USGS determining what the cause of this disruption was.

Jonathan Lees, a professor in the Department of Earth, Marine and Environmental Sciences at UNC, said earthquakes are uncommon in North Carolina, especially in the Piedmont.

“I expect that there will be earthquakes along the Piedmont from time to time, but on the human timescale — I think it’s 1,000 years — it would feel like it’s a very, very rare occurrence,” he said.

Lees said the amount of destruction coming from an earthquake is shown in the magnitude. He said earthquakes under a magnitude of four typically have minimal or no damage, while those above it lead to more destruction.

He also said there is no way to determine when an earthquake is about to come. Those studying earthquake trends rely on statistical methods to determine the probability of one occurring, he added.

“We do not predict earthquakes, we forecast earthquakes,” Lees said.

Though earthquakes are rare in the area, Pickhardt said she recommends people be prepared for any natural disaster. She said the Orange County alert system is a good source for receiving public safety messages.

“My recommendation really would be for folks to be ready for any kind of natural hazard, whether that’s earthquakes, weather or anything in between,” she said.

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