A powerful earthquake of 5.8 magnitude struck off North Korea in the Sea of Japan on Thursday, the US Geological Survey said. However, it was unlikely to cause any damage.
The authorities said that the quake hit early in the morning at a depth of 538 km below the seabed. Its epicentre was 180 km southeast of the North Korean city of Chongjin. Initially, it was reported as a magnitude 6.0 but was later revised to 5.8.
USGS seismologist Julie Dutton told Reuters that an earthquake of that size is unusual for that area but not unprecedented. She said the last large quake in that part of the Sea of Japan was in 1994.
North Korea causes seismic events when it conducts underground nuclear bomb tests, but Dutton said there was nothing to indicate this quake was a man-made event. All of North Korea's underground nuclear tests have been conducted on land.
In response to this, Major Jamie Davis, a Pentagon spokesman said that initial indications showed that the earthquake was not caused by a North Korean nuclear test because of the location and depth of the quake. He added that the Pentagon would continue to study the seismic activity.