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US Airmen in Australia keep an ear to the ground

Airmen assigned to the 709th Technical Maintenance Squadron, Detachment 421, pose for a group photo in this composite image in Alice Springs, Australia, Aug. 28, 2019. The Airmen are responsible for maintaining a 20-sensor seismic array, which monitors vibrations in the Earth’s crust and can detect nuclear detonations. (U.S. Air Force photo illustration by Master Sgt. Benjamin Wilson)

This report originally published at dvidshub.net (DVIDS) and is reprinted in accordance with DVIDS guidelines and copyright guidance.

Earthquakes, tsunamis and nuclear explosions all have one thing in common – when they happen, the Airmen of Detachment 421 know.

Situated in the remote outback of Central Australia, the 709th Technical Maintenance Squadron Det 421 is responsible for maintaining a seismic array, which can remotely detect the detonation of nuclear bombs.

The array is made up of 20 individual sensors spread over 100 square kilometers (38.6 square miles), which act like microphones in the bedrock to detect vibrations in the earth. The data collected on site is sent to analysts with the Air Force Technical Applications Center at Patrick Air Force Base, Florida, to determine the origin of the activity.

“We’re basically the first points of the chain when a nuclear event happens,” said Master Sgt. Jonathon Beedham, Det 421 chief. “If there was a manmade event or a natural event, such as an earthquake, those signals travel through the earth and are received by seismometers around the world. That data goes back to a central location and is analyzed to provide an accurate time and location of the source.”

That information is provided to national decision makers to help determine the capabilities of foreign nations, Beedham said.

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In addition to aiding the nuclear deterrence mission, the unit partners with Geoscience Australia to provide data for early warning tsunami systems in the Pacific. When undersea earthquakes are detected by the detachment Geoscience Australia sends the information to the Joint Australia Tsunami Warning Centre to assess its potential threat.

Although there are several seismic arrays operated and maintained around the globe, the terrain in Central Australia makes for ideal conditions.

“The unique thing about Alice Springs is we are so remote. We are essentially an island in the middle of an island,” said Tech. Sgt. Andrew Bryan, Det 421 noncommissioned officer in charge of maintenance. “We’re thousands of miles from any major city.”

Because the unit’s location is so far removed from the main population of Australia they do not have to deal with problems caused by development. Construction crews, busy highways and other consequences of densely populated areas can create noise, which make it harder to detect signals in the earth’s crust, according to Bryan.

That coupled with the geological conditions at the location make for optimal listening.

“In Alice Springs the bedrock is really close to the surface of the Earth,” Bryan said. “We don’t have to dig that deep to get into solid bedrock and having that acts as a giant microphone for everything going on in the earth. It gives us high fidelity on what we are seeing underground.”

The sensors are buried in a metal pipe about 90 feet underground and coupled solidly to the bedrock. Inside the pipe a free-floating magnet is surrounded by a metal coil. When the Earth’s crust moves, the coil around the magnet moves with it creating an electrical signal, which is sent over telephone wires to the recording station.

Time and intensity differences between the sensors enable the analysts to determine the direction and distance of the source. That requires the sensors to be spread across large expanses of land.

The team of Airmen maintain cables and sensor locations on city property, the Northern Territory Recreation and Parks Association land, as well as two privately owned cattle farms. However, cattle are not the only wildlife they encounter while working in the outback.

“We meet all kinds of interesting creatures,” Beedham said. “Mostly snakes and lizards. We have the Western Brown and the King Brown Snake.”

There are also deadly spiders to deal with and unexpected road hazards such as kangaroos and free-roaming camels.

The four Airmen assigned receive driving training upon arrival due to the extreme conditions they must traverse to reach their work sites. They use four-wheel-drive vehicles with diesel engines, a quality suspension and lift kit to pull them along the off-road paths.

“Those vehicles allow us to get to about 40% of our sites that would otherwise be unreachable by conventional vehicles,” Beedham said. “We also have one all-terrain vehicle, which allows us to get to our cable plant lines.”

Some of those lines, which the Det 421 Airmen maintain, have been buried and transmitting vital data for 65 years.

“We are honored to carry on the tradition and legacy of the Airmen that have come before us,” Beedham said. “We started back in 1955. It has changed over the years and the resiliency and innovation of our Airmen, always adapting to new technologies, allows us to have been out here for a long time doing this mission.”

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