Sonar, Sosus and “Rebalancing,” and What it Means for Marine Life by Carol Turner

Orca or Killer Whale breaching.
Courtesy of NOA

The Navy’s plans to increase the number of sonobuoys used in their training exercises are making news in the Pacific Northwest. These are the same training exercises that include the controversial trucks that would emit electromagnetic radiation and send signals to Growler jets flying overhead.

A “sonobuoy” is a sonar signaling and receiving device dropped from an aircraft. Other sonar devices used in naval training include dipping sonar, exercise torpedoes, acoustic countermeasures, and training targets equipped with sonar. The real story is not the sonobuoy itself but the broader subject of sonar and its role in the United States’ recent strategy of “rebalancing” the Navy’s assets toward Asia.

Sonar has a fascinating history. It involves the science of ocean acoustics, our underwater Cold War with the Soviet Union, a traitor named John Walker, glasnost, and finally, the rise of China and the development of their navy.

The ocean’s sound superhighway

The ocean is a giant acoustical cavern. The water’s surface and the seabed both reflect sound. Five hundred years ago, Leonardo DaVinci stuck a long hollow tube into the Mediterranean and listened to ships passing by miles away.

In 1822, Swiss physicist Daniel Colladen used a bell to measure the speed of sound through water. He hammered on the bell under water while lighting a flash of gunpowder in a boat. Several miles away, someone in another boat compared the gunpowder flash to the sound of the bell, using Leonardo’s hollow tube technique to listen. They learned that sound travels almost five times faster underwater than in the air. This experiment gave birth to “Sound Navigation and Ranging,” or sonar.

The early 1900s saw the invention of sonar listening devices for detecting icebergs and submarines, and the technology has since developed into myriad forms of active (emitting sound) and passive (listening) sonar devices operating at various frequencies and decibel levels.

In the 1940s, while studying the seismology of the ocean floor geophysicist Maurice Ewing made a startling discovery – a layer of ocean water where sound waves become “trapped” and can travel uninterrupted for many thousands of miles. Created by water pressure and temperature, in one experiment this “deep sound channel” carried the sound of a dropped charge in Australia. Three hours later it was picked up in Bermuda – 12,000 miles away.

The Cold War, Sosus, and the Spy

Ewing’s discovery played a critical role in the Cold War between the United States and the Soviet Union, much of which was waged in the hidden world beneath the waves.

In the early 1950s, as Cold War pressures gathered steam, the Americans developed a top secret, highly sophisticated system of listening devices that took advantage of Ewing’s deep sound channel. Its function was to locate and track Soviet subs. Called the Sound Surveillance System, or Sosus, it consisted of low-frequency listening devices attached to 30,000 miles of telephone cables strung across the world’s seabeds. The US and her allies had literally bugged the oceans.

Soviet submarines of that era were noisy. What the Soviets didn’t know was that, from thousands of miles away, Sosus could hear, identify and track their movements. Years later, one former Soviet submarine commander compared Sosus technology to putting an American on the moon.

October of 1962 brought the Cuban Missile Crisis, probably the most dangerous moment in the Cold War. The US identified 25 ships bringing Soviet warheads to Cuba and erected a blockade. The Soviet Union also sent four Foxtrot nuclear submarines toward Cuba, each carrying two nuclear warheads. Sosus detected and tracked the subs and the Americans forced three of them to the surface.

During the 1970s, Soviet submarines began to act like they knew someone was watching them. In 1985, US Naval Intelligence arrested a naval officer, John Anthony Walker, for spying. Walker and a small spy ring of family and friends had been selling secrets to the Soviets since 1968, including information about Sosus. Walker died in prison in October 2014.

This betrayal destroyed America’s edge in the underwater Cold War. The Soviets developed quieter subs and long range missiles that allowed them to stay out of the Atlantic – the primary area of Sosus coverage.

The End of the Cold War and the Rise of China

The late 1980s saw the collapse of the Soviet Union, glasnost, and the end of the Cold War. Eventually, Sosus was taken offline. All but three of the 22 Sosus monitoring facilities were shut down. During the 1990s, scientists used the remaining stations to research marine mammals, particularly the critically endangered North Atlantic right whale.

Recently, however, Sosus is being revitalized due to the rise of the Chinese Navy. In today’s political climate, neither the US nor China wants to wage a Cold War style submarine game in the Pacific. Primarily motivated by economics, China is a close trade partner with the US and hasn’t shown signs of wanting to compete militarily.

However, China has interests in Taiwan and territorial disputes with Japan and the Philippines – two U.S. allies. China has recently joined the “nuclear sub club” and has four “boomers,” or nuclear submarines carrying ballistic missiles. The missiles are capable of reaching Hawaii and Alaska from Chinese waters or the US mainland from the mid-Pacific. The result of all this, according to the Wall Street Journal, is that the US Navy is “rebalancing” its strategy toward Asia.

The Navy’s Northwest Training Exercises

Part of this rebalancing will be continued training exercises in the waters of the Pacific Northwest, presumably stepped up from previous years. The Navy’s 2014 environmental impact draft for their testing and training plan is nearly a thousand pages. They describe numerous activities for the northwest region, much of which involves firing missiles, cannons, torpedoes, and bombs at seagoing targets. A “SINKEX” exercise destroys a decommissioned ship.

They’ll practice detecting and identifying submarines. They’ll hunt for mines, then destroy or disable them. A category called “special warfare” uses submersible vehicles for “extraction and insertion missions.” Their current plans for testing electronic warfare equipment using trucks emitting electromagnetic radiation in the Olympic National Forest have already caused an uproar (but that’s another story).

The Impact on Marine Life

The Navy document also describes the noise, physical disturbances, entanglements, ingestion, effect on air and water quality, and other stressors that will likely be placed on the environment. It describes the marine life and the type of injuries and behavioral changes the animals could sustain, and lists endangered species that might be found in the test area, including the Humpback whale, Blue whale, Fin whale, Sei whale, Gray whale, Sperm whale, Orca or Killer whale, North Pacific Right whale and the Leatherback sea turtle. The document describes possible trauma to sea turtles from explosives but states that most of the activities “may affect, not likely to adversely affect” the endangered whales. It’s not clear whether other scientists would agree with those conclusions.

When the Navy prepares for their exercises, they basically have to get permission from other government agencies to “take” a specified number of marine mammals as “incidental” casualties of the exercises. Many of these “takes” are caused by the use of sonar.

Unfortunately for many whales, dolphins and other marine life, the use of underwater sonar (short for sound navigation and ranging) can lead to injury and even death,” according to Scientific American (“Does Military Sonar Kill Marine Life?” June 10, 2009). The sonar sound waves can reach up to 235 decibels at the source and retain the intensity of 140 decibels 300 miles away. As a comparison, damage to the human ear begins at 80 to 85 decibels. Gunshots can generate sounds between 145 to 190 decibels.

In recent years, non-profits such as Natural Resources Defense Council (NRDC) have filed lawsuits, asking for restrictions on more intense and harmful types of sonar and to enact safety precautions such as lowering the decibel level or delaying tests when animals are spotted. In 2008, a federal court in Los Angeles ordered the Navy to implement a number of NRDC-requested safeguards. This case went to the US Supreme Court which upheld four of six requested precautions.

In 2012, a group of scientists sent an open letter to US and Canadian officials, asking that naval exercises stop employing mid-frequency active (MFA) sonar in the Salish Sea, a critical habitat of the endangered Southern Resident Orca. Orcas use the same frequency range to communicate and locate prey, a process that is disrupted by the intense levels used by the Navy. The request was prompted by incidents of unusual Orca “nearshore surface milling behavior” that occurred soon after naval exercises using sonar. The 2014 training document indicates that MFA sonar will be used.

As the Navy ramps up its new policy of “rebalancing” toward Asia, those who care about the well-being of marine life and the rainforest hope to find workable compromises between securing our shores and protecting the environment. Here in the Pacific Northwest, we may be on the front lines of that battle.

1 Comment

  1. Francisco

    Good informative article. Keep them coming.


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