Seoul: A small earthquake rattled the area near North Korea’s nuclear testing field but it did not appear to be manmade, South Korea’s weather agency said on Friday, the latest to be observed after the North conducted its sixth and biggest nuclear test in early September.

Friday’s quake was a magnitude 2.7 with a depth of 3 km in North Hamgyong Province in North Korea, the Korea Meteorological Administration said, near the Punggye-ri nuclear testing site.

The United States Geological Survey (USGS) measured the quake at 2.9 magnitude with a depth of 5 km and added it could not conclusively confirm its nature.

It was the latest in a string of aftershocks following North Korea’s sixth nuclear test on 3 September, which caused a 6.3 magnitude earthquake, according to the USGS. These have prompted experts and observers to suspect the last test may have destabilised the mountainous location.

All six nuclear tests have been carried out in this location in the northwest tip of the country. According to 38 North, a Washington-based project which monitors North Korea, numerous landslides throughout the nuclear test site have been detected via satellite images after the sixth test.

These disturbances are more numerous and widespread than seen after any of the North’s previous tests, 38 North has said.