Aftershocks have continued ever since, and on Saturday the US Geological Survey said it had detected two more, sparking significant debate about what might be going on underground.What happened during the nuclear test?
On 3 September, North Korea tested its most powerful nuclear bomb to date at its Punggye-ri test site in the mountains in its northwest.
Pyongyang claimed it was a hydrogen bomb, which would have made it a device many times more powerful than an atomic bomb.
Experts have expressed concerns the explosion might have been so powerful it could destabilise the surrounding mountains.
Why are aftershocks still happening?
According to the USGS, last weekend's tremors were "relaxation events". They measured a magnitude of 2.9 and 2.4.
"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," an official told Reuters.
The "movement of the earth's crust" is akin to the very definition of an earthquake and scientists say it is only to be expected in the weeks and months after an explosion of that magnitude.
"These aftershocks for a 6.3 magnitude nuclear test are not very surprising," Dr Jascha Polet, seismologist and professor of geophysics at California State Polytechnic University, told the BBC.
After any tremor of that size, aftershocks with declining magnitude are common, as the rock moves around and releases stress.
The area around the quake site "experiences deformation, and this creates areas of increased and decreased stress, which affects the distribution of aftershocks," Ms Polet said.
"The fact that the source of the earthquake is an explosion doesn't change how we expect the energy to redistribute," geophysicist and disaster researcher Mika McKinnon, told the BBC.
But research on explosions of a similar magnitude as the North Korea nuclear test at the Nevada Test Site in the US where over decades nuclear tests were carried out, has found that the aftershocks of these events were fewer in number and lower in magnitude.
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