North Korea said it conducted its fifth underground nuclear test on Friday. Since the first test, almost a decade ago, the size of the resulting earthquakes from the country’s test site have increased, indicating that the devices are becoming increasingly powerful.
The device detonated on Friday looks to have had a force equivalent of 10 kilotons of TNT, according to the South’s Defence Ministry. In contrast, the last device tested by the North, in January, had a force equivalent of six kilotons of TNT, the South’s intelligence agency said. The aboveground Trinity Test in New Mexico in July 1945, which ushered in the nuclear age, had a yield of 20 kilotons.
Here is a timeline of how North Korea built up the capability of its nuclear weapons. The earthquake magnitudes are from the United States Geological Survey, which differ from those measured by the South Korean authorities. They may also be slightly revised from numbers reported immediately after the events.
Oct. 8, 2006
Magnitude of Earthquake: 4.3
Device: United States officials said at the time that the weapon used plutonium and had a yield of less than one kiloton.
Missiles: Three months before the nuclear test, North Korea fired a barrage of missiles into the Sea of Japan, including a Taepodong 2 intercontinental missile designed to be capable of reaching Alaska. The Taepodong 2 test was a failure, with the missile falling into the sea before its first stage burnt out.
May 24, 2009
Magnitude of Earthquake: 4.7
Device: Chinese scientists estimated that this bomb had a yield of 2.35 kilotons.
Missiles: A failed satellite launch using a Taepodong 2 missile in April 2009 sent its payload into the Pacific Ocean. On July 4, 2009, North Korea launched three missiles into the sea, with none apparently flying more than 500 Kms.
Feb 12, 2013
Magnitude of Earthquake: 5.1
Device: North Korea said this bomb, stronger than the first two tests, was miniaturised. After the launch, the Pentagon’s Defense Intelligence Agency estimated with “moderate confidence” that North Korea had learnt how to make a miniaturised nuclear weapon capable of being delivered by a ballistic missile. But the report said the weapon’s “reliability will be low.” Military officials in the United States and South Korea publicly expressed doubt that North Korea had actually developed such a warhead.
Missiles: In May 2013, North Korea launched three short-range missiles into the Sea of Japan.
Jan. 5, 2016
Magnitude of Earthquake: 5.1
Device: North Korea claimed this device was a hydrogen bomb. In May, American and South Korean intelligence officials concluded that North Korea was now able to mount nuclear warheads on short- and medium-range missiles that would be capable of hitting Japan and South Korea.
Missiles: In April, North Korea launched a missile from a submarine.
Sept. 8, 2016
Magnitude of Earthquake: 5.3
Device: South Korean officials said this was North Korea’s most powerful device to date.
Missiles: In June, North Korea successfully launched an intermediate-range ballistic missile into high altitude after five consecutive failures. The missile may be capable of reaching American forces based on Guam, in the Pacific Ocean.
