Operation Wigwam involved a single test of the Mark 90 "Betty" nuclear bomb. It was conducted between ''

Operation Teapot Operation Teapot was a series of 14 nuclear test explosions conducted at the Nevada Test Site in the first half of 1955. It was preceded by ''Operation Castle'', and followed by ''Operation Wigwam''. ''Wigwam'' was, administratively, a part of ...

'' and '' Project 56'' on May 14, 1955, about 500 miles (800 km) southwest of

San Diego San Diego ( , ) is a city on the Pacific coast of Southern California, adjacent to the Mexico–United States border. With a population of over 1.4 million, it is the List of United States cities by population, eighth-most populous city in t ...

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

. 6,800 personnel aboard 30 ships were involved in ''Wigwam''. The purpose of ''Wigwam'' was to determine the vulnerability of submarines to deeply detonated nuclear weapons, and to evaluate the feasibility of using such weapons in a combat situation. The task force commander, Admiral John Sylvester, was embarked on the task force

flagship A flagship is a vessel used by the commanding officer of a group of navy, naval ships, characteristically a flag officer entitled by custom to fly a distinguishing flag. Used more loosely, it is the lead ship in a fleet of vessels, typically ...

. ''Wigwam'' was the first atomic test in the deep ocean, and it remains the only test that has been conducted in water deeper than .

Detonation layout and test

The test device was suspended to a depth of by cable attached to a

barge A barge is typically a flat-bottomed boat, flat-bottomed vessel which does not have its own means of mechanical propulsion. Original use was on inland waterways, while modern use is on both inland and ocean, marine water environments. The firs ...

. A tow line connected the Cherokee-class fleet tug, , to the shot barge. Suspended from the tow lines of other tugs were three miniature unmanned target

submarine A submarine (often shortened to sub) is a watercraft capable of independent operation underwater. (It differs from a submersible, which has more limited underwater capability.) The term "submarine" is also sometimes used historically or infor ...

s designated "SQUAWS", each packed with cameras and telemetry instruments. Those targets were long, scale of the SS-563 prototype hull () to assess effects of the explosion on a submarine hull. The time of detonation was 13:00 local Pacific Time (noon Pacific Standard Time). The equipment intended for direct measurement of the explosion-generated underwater bubble was not operational at the time of the shot, but based on other measurements, the bubble's maximum radius was calculated as , and its pulsation period approximately 2.83 seconds. See also the table at List of United States' nuclear weapons tests.

Underwater sound

The underwater

sound In physics, sound is a vibration that propagates as an acoustic wave through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the ''reception'' of such waves and their ''perception'' by the br ...

from the Wigwam explosion was recorded on bottom-mounted

hydrophone A hydrophone () is a microphone designed for underwater use, for recording or listening to underwater sound. Most hydrophones contains a piezoelectric transducer that generates an electric potential when subjected to a pressure change, such as a ...

s at Point Sur and Point Arena off California, and at Kāneʻohe Bay off

Oahu Oahu (, , sometimes written Oahu) is the third-largest and most populated island of the Hawaiian Islands and of the U.S. state of Hawaii. The state capital, Honolulu, is on Oahu's southeast coast. The island of Oahu and the uninhabited Northwe ...

Hawaii Hawaii ( ; ) is an island U.S. state, state of the United States, in the Pacific Ocean about southwest of the U.S. mainland. One of the two Non-contiguous United States, non-contiguous U.S. states (along with Alaska), it is the only sta ...

. The sound emanating from the explosive test began as an intense water

shock wave In physics, a shock wave (also spelled shockwave), or shock, is a type of propagating disturbance that moves faster than the local speed of sound in the medium. Like an ordinary wave, a shock wave carries energy and can propagate through a me ...

. As the sound traveled away from the test point, it reflected from topographic features, such as

island An island or isle is a piece of land, distinct from a continent, completely surrounded by water. There are continental islands, which were formed by being split from a continent by plate tectonics, and oceanic islands, which have never been ...

s and

seamount A seamount is a large submarine landform that rises from the ocean floor without reaching the water surface (sea level), and thus is not an island, islet, or cliff-rock. Seamounts are typically formed from extinct volcanoes that rise abruptly a ...

s, located throughout both the North and South Pacific Basins. The reflected sound was then recorded as hours-long coda at Kaneohe and Point Sur. Some of the acoustic energy travelled round trip distances of over . The sound signals provided one of the early measurements of underwater sound

attenuation In physics, attenuation (in some contexts, extinction) is the gradual loss of flux intensity through a Transmission medium, medium. For instance, dark glasses attenuate sunlight, lead attenuates X-rays, and water and air attenuate both light and ...

at low frequencies.

Detonations

The detonations in the United States' ''Wigwam'' series are listed below:

References

Explanatory notes

Citations

External links

*
14 May 1955—Wigwam
��A description of the WIGWAM test and its radiation aftereffects at the Comprehensive Nuclear-Test-Ban Treaty Organization Preparatory Commission Web site {{Nuclear weapons tests of the United States 1955 in California 1955 in military history

Wigwam A wigwam, wikiup, wetu (Wampanoag), or wiigiwaam (Ojibwe, in syllabics: ) is a semi-permanent domed dwelling formerly used by certain Native American tribes and First Nations people and still used for ceremonial events. The term ''wikiup'' ...

Articles containing video clips Explosions in 1955 May 1955 in Oceania Military history of the Pacific Ocean