This map layer has a time line (1946–2017) and, for the selected year, shows the number of nuclear tests carried on by countries on their respective soil or on that of other countries above ground, below ground, atmospherically or under water on the real test sites, divided into five categories.
The United States carried out the first nuclear test in 1945. The test was followed by the only drops of one atom bomb on Hiroshima and one on Nagasaki towards the end of World War II. As, due to the state of war, it was difficult to demarcate many borders, the timeline starts in 1946. The so far most recent, though officially not confirmed, nuclear test was carried out by North Korea in 2009. All in all, 2,161 nuclear explosions (above or below ground, atmospherically or under water) were triggered by man. This number is partially based on the measurements obtained from the seismic activities and any nuclear radiation caused by the tests as not all countries report their nuclear tests. Geoscience Australia's database on nuclear explosions is the main source of this presentation and has been complemented by data from the US Department of Energy. The last nuclear test has been added to this collection of data in 2009. Subcritical nuclear tests, that is tests that have not triggered a chain reaction and that have not released radiation, are not listed.