The last time we checked in on North Korea, earthquakes and tunnels collapses have continued in the mountain range that has been the rogue nation’s nuclear test site.

The tremors have continued, as the entire area remains geologically unstable.

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.

Meanwhile, China is preparing for massive social instability in its neighbor. The New York Times is reporting that China is planning to build five camps that could accommodate thousands of North Korean refugees.

According to The Times, a leaked document from state-run China Mobile that appeared on the microblogging site Weibo, said the telecommunications company was contacted to check for “viable internet service” at the five sites in the northeast border province of Jilin.

“Because the situation on the China-North Korea border has intensified lately, Changbai County government plans to set up five refugee sites in Changbai,” the document reportedly stated.

When questioned by The Times, a spokesperson for China’s foreign ministry said they were not aware of reports about the refugee camps, but did not deny the plans to build them.

On the other side of North Korea, the United States, Japan and South Korea are teaming up for a drill to track submarine-launched ballistic missiles.

The drill is taking place over two days in waters between Japan and the Korean Peninsula, said South Korea’s Joint Chiefs of Staff, and will involve destroyers from the three nations doing computer-simulated training to track submarine missile launchings by North Korea.

The drills come in the wake of news reports that North Korea is making progress developing submarine-launched ballistic missiles, or SLBMs. The website 38 North, based at the U.S.-Korea Institute at Johns Hopkins University, obtained images of cylindrical objects, evidence that “suggests construction of a new submarine” at a facility on North Korea’s east coast.

It may be that soon, the weather will be the only thing Kim Jong Un controls.