6�E), was used in 1955�1962 and 1972�1975. "Zone B", Matochkin Shar (73.4�N 54.9�E), was used for underground tests in 1964�1990. "Zone C", Sukhoy Nos (73.7�N 54.0�E), was used in 1958�1961 and was the 1961 explosion site of the 100 megaton (fired device was a downgraded design to 50) Tsar Bomba, the biggest nuclear bomb ever detonated.
Other tests occurred elsewhere throughout the islands, with an official testing range covering over half of the landmass. In September 1961 two propelled thermonuclear warheads were launched from Vorkuta Sovetsky and Salekhard respectively to target areas on Novaya Zemlya. The launch rocket was subsequently deployed to Cuba.
1963 saw the implementation of the Limited Test Ban Treaty outlawing most atmospheric nuclear tests. The largest underground test at Novaya Zemlya took place on September 12, 1973, involving four nuclear devices of 4.2 megatons total yield. Although far smaller in blast power than the Tsar Bomba and other atmospheric tests, the confinement of the blasts underground led to pressures rivaling natural earthquakes. In the case of the September 12, 1973, test, a seismic magnitude of 6.97 on the Richter Scale was reached, setting off an 80 million ton avalanche that blocked two glacial streams and created a lake 2 kilometres (1.2 mi) in length.
Over its history as a nuclear test site, Novaya Zemlya hosted 224 nuclear detonations with a total explosive energy equivalent to 265 megatons of TNT. For comparison, all explosives used in World War II, including the detonations of two U.S. nuclear bombs, amounted to only two megatons.
In 1988�1989, glasnost helped make the Novaya Zemlya testing activities public knowledge, and in 1990 Greenpeace activists staged a protest at the site. The last nuclear test explosion was in 1990 (also the last for the entire Soviet Union and Russia). The Ministry for Atomic Energy has performed a series of subcritical underwater nuclear experiments near Matochkin
