The U.S. used the pacific atolls because they were isolated from large population centers and because the Marshal Islands (where many of these atolls were) were entirely under U.S. control after WW2, so could freely involuntarily evacuate indigenous populations of the atolls that testing was planned on.
The USSR did all of their testing inland for security reasons (they also did not have control over any atolls).
The British did much of their testing inland on Australia and some in the pacific on Christmas island.
The French did their testing in the Sahara desert.
The Chinese did all of their testing inland for security reasons.
etc.
One of the main reasons was its isolation.
The Bikini Atoll is an atoll in the Marshall Islands and was the site of many American nuclear tests in the 1940s and 1950s.
The French conducted nuclear testing in the Tuamotu islands, on the atoll of Mururoa. The US conducted nuclear testing on the atoll of Bikini in the Marchall islands.
The French conducted nuclear tests on the Mururoa Atoll.
No they did not yet
The US tested on Bikini atoll, Eniwetok atoll, and launched some high altitude tests from Johnston island on rockets. The UK tested on Christmas island.
The first time nuclear testing was done in the Pacific was in 1946. Tests were conducted at the Marshall Islands, Bikini Atoll and a few other "nondescript" sites. Testing continued by the US in the Pacific up until 1962. France also conducted its own tests in French Polynesia, between 1966 and 1996.
In July of 1946, the United States dropped an atomic bomb on Bikini Atoll. In the coming years, the island was used for another twenty additional bomb tests.
The US tested nuclear devices in the Trinity test site in NM, Bikini atoll in the Marshal islands, Eniwetok atoll in the Marshal islands, underwater offshore Mexico in international waters south of San Diego CA, the Nevada test site north of Las Vegas NV, in space, and for project Plowshare (peaceful uses of nuclear explosives) in about half a dozen other states.The USSR tested nuclear devices at 2 or 3 sites in Siberia and its largest fusion bomb tests were on the arctic island of Novaya Zemlya.The UK tested nuclear devices in Australia.France tested early nuclear devices in the Sahara desert while it still had colonies there, since then I'm not sure.
It is improbable that underground nuclear tests can alter the axial tilt of the earth.
Harry S Truman was president during the Bikini Atoll atomic tests.
None.
Bikini Atoll. The name was in the news so much that it was taken for a new type of two-piece ladies swimsuit from a daring French designer appearing at around the same time, equally hot.