Amchitka is a volcanic, tectonically unstable island that is part of the Aleutian Islands chain in southwester Alaska. Located roughly 1,000 miles off the western coast of Alaska, this island was home to a small population of native Aleut for nearly 2,500 years, until around 1832. After that year, the island was abandoned and left uninhabited. During World War II, the island became an air base for the United States. At its peak, the occupancy of the island reached 15,000 soldiers. In 1950, the communications facility was closed and all personnel were removed from the island. Following the withdrawal from the island in 1950, the Atomic Energy Commission (AEC) considered the island as a site for nuclear testing. However, the island was deemed unsuitable for testing and the Nevada Test site was chosen instead.
In the late 50s, scientists realized that in order to detect Soviet underground nuclear testing, they would need to better understand how the explosions related to earthquakes. In other words, they wanted to be able to differentiate underground nuclear tests from natural earthquakes caused by seismic activity and have the ability to locate the location of the test. In 1964, the AEC and Department of Defense (DoD) reoccupied Amchitka with the goal, “to determine the behavior and characteristics of seismic signals generated by nuclear detonations and to differentiate them from seismic signals generated by naturally occurring earthquakes.” Some environmentalists feared that due to the island’s position on a tectonic plate, the tests could trigger earthquakes and tsunamis, endangering wildlife and human populations as far as Japan.
Between 1964 and 1971, three tests were conducted on the island. The first, named Long Shot, was the first underground test conducted in a remote area. The yield was 80 kilotons, small relative to other underground tests conducted at the Nevada Test Site. The second detonation, named Milrow, served as a test to see if the island could withstand a detonation of a much larger nuclear warhead. With a yield of 1.2 megatons, the test was deemed a success and plans for a third test were set into action. The third and final test conducted at Amchitka was named Cannikin. The yield was 5 megatons, making it the largest underground nuclear test in U.S. history. To put that into perspective, this bomb was 400 times more powerful than the atomic bomb dropped on Hiroshima. The explosion generated a seismic shock of 7.0 on the Richter scale, causing massive rockfalls and influencing small seismic activity in surrounding areas.
Though earthquakes and tsunamis predicted by environmentalists did not occur, there were some undesirable and unanticipated consequences of the tests. The most notable were the damage to the sea otter population and the long lasting radioactivity in of the environment. It was predicted that almost 2,000 sea otter were killed due to the blast, a much larger number than predicted by the AEC. Studies in the 1990s reported plutonium and americium had leaked into the environment. The Department of Energy has continuously monitored the site as part of its remediation program. This is expected to continue until 2025, after which the island will be designated as a wildlife preserve.