The United States Geological Survey (USGS) on Thursday detected a 2.9 magnitude earthquake 23km northeast of Sungjibaegam in North Korea, near the country’s nuclear testing site.

The quake took place at 1641 (UTC) at an estimated depth of 5km, and while the USGS said the quake appeared natural, it did not rule out the possibility of a nuclear test.

“This event occurred in the area of the previous North Korean Nuclear tests,” the USGS said in a statement. “The event has earthquake like characteristics, however, we cannot conclusively confirm at this time the nature (natural or human-made) of the event.”