Operation Wigwam involved a single test of the Mark 90 "Betty" nuclear bomb. It was conducted between '' Operation Teapot'' and '' Project 56'' on May 14, 1955, about 500 miles (800 km) southwest of

San Diego San Diego ( , ; ) is a city on the Pacific Ocean coast of Southern California located immediately adjacent to the Mexico–United States border. With a 2020 population of 1,386,932, it is the eighth most populous city in the United State ...

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

. 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 . ''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 Barge nowadays generally refers to a flat-bottomed inland waterway vessel which does not have its own means of mechanical propulsion. The first modern barges were pulled by tugs, but nowadays most are pushed by pusher boats, or other vessels ...

. 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 submarines 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 1300 hrs 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'' b ...

from the Wigwam explosion was recorded on bottom-mounted

hydrophone A hydrophone ( grc, ὕδωρ + φωνή, , water + sound) is a microphone designed to be used underwater for recording or listening to underwater sound. Most hydrophones are based on a piezoelectric transducer that generates an electric potenti ...

s at

Point Sur Point Sur State Historic Park is a California State Park on the Big Sur coastline of Monterey County, California, United States, south of Rio Road in Carmel. The 1889 Point Sur Lighthouse is on the National Register of Historic Places. Hist ...

and Point Arena off California, and at

Kāneʻohe Bay Kāneohe Bay, at , is the largest sheltered body of water in the main Hawaiian Islands. This reef-dominated embayment constitutes a significant scenic and recreational feature along the northeast coast of the Island of Oahu. The largest populati ...

off

Oahu Oahu () ( Hawaiian: ''Oʻahu'' ()), also known as "The Gathering Place", is the third-largest of the Hawaiian Islands. It is home to roughly one million people—over two-thirds of the population of the U.S. state of Hawaii. The island of O� ...

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. 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 travelled away from the test point, it reflected from topographic features, such as

island An island (or isle) is an isolated piece of habitat that is surrounded by a dramatically different habitat, such as water. Very small islands such as emergent land features on atolls can be called islets, skerries, cays or keys. An island ...

s and seamounts, 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 medium. For instance, dark glasses attenuate sunlight, lead attenuates X-rays, and water and air attenuate both light and sound at variabl ...

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 The Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) is an international organization that will be established upon the entry into force of the Comprehensive Nuclear-Test-Ban Treaty, a Convention that outlaws nuclear test explosions. It ...

Preparatory Commission Web site {{Nuclear weapons tests of the United States 1955 in California 1955 in military history

Wigwam A wigwam, wickiup, 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 ''wickiup' ...

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