On September 3, North Korea successfully tested what state-run news outlets called a “two-stage thermonuclear weapon.” The underground explosion at the northeastern Punggye-ri nuclear test site produced a 6.3 magnitude artificial earthquake according to the U.S. Geological Survey. Estimates of the yield have ranged from between 50 and 60 kilotons, according to South Korea’s weather agency, to over 100 kilotons according to a Norway-based group. Experts believe the most recent explosion is between four and sixteen times larger than any nuclear weapon North Korea has tested before. The test occurred shortly after KCNA released photographs of Kim Jong-un inspecting a peanut looking two-stage nuclear device, which many believe was the weapon tested. A second smaller quake was detected shortly after the first one, suggesting the possibility of a tunnel collapse as a result of the test.