Tremors, Aftershocks Felt Near North Korean Nuclear Missile Test Site

As tensions grow between the United States and North Korea, the U.S. and its allies are constantly on the lookout for signs of potential nuclear weapons tests and missile launches in the isolated country. The U.S. Geological Survey (USGS) earthquake monitoring service is no exception, as nuclear tests typically generate aftershocks some time after each test.

According to a Reuters report, this happened again in the vicinity of the Punggye-ri nuclear test site Saturday.

Measuring at magnitude 2.9 and 2.4, the small aftershocks occurred in the middle of the night in U.S. time. North Korea tested what it called a hydrogen bomb at the site in its sixth and largest underground nuclear test back in September, which Reuters reports would be around 10 times more powerful than the atomic bombs used at the end of World War II.

USGS officials told Reuters that the tremors were close to the Punggye-ri nuclear test site, where the country conducted its sixth -- and largest -- underground nuclear test on September 3.

“They’re probably relaxation events from the sixth nuclear test,” a USGS official told Reuters. “When you have a large nuclear test, it moves the earth’s crust around the area, and it takes a while for it to fully subside. We’ve had a few of them since the sixth nuclear test.”

Relations between the U.S. and North Korea have never been positive since the Korean War paused with a ceasefire in 1953, but they have taken a turn for the worse during the Trump administration. President Trump has threatened military action against North Korea in the face of that country's nuclear tests, and U.S. tourism to North Korea was ended in July.