Defense Nuclear Monitoring System Helps in Disasters

WASHINGTON, July 14, 2011 — The Defense Department’s U.S. Atom­ic Ener­gy Detec­tion Sys­tem has mon­i­tored the plan­et for nuclear blasts since 1947, but its sen­sors also help to pin­point and assess large nat­ur­al dis­as­ters around the world.

An Air Force tech­ni­cian per­forms depot repair of a seis­mome­ter. The instru­ment will be returned to ser­vice at one of 40 seis­mic sta­tions around the globe to detect nuclear tests.
U.S. Air Force pho­to
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Since 1980, this state-of-the-art sys­tem, called USAEDS, has been the respon­si­bil­i­ty of the Air Force Tech­ni­cal Appli­ca­tions Cen­ter at Patrick Air Force Base, Fla. 

AFTAC’s job is to make sure for­eign nations adhere to three nuclear test-ban treaties that have been in force since the 1960s and 1970s and that pro­hib­it nuclear test­ing in the atmos­phere and some under­ground tests. 

But the increas­ing­ly sophis­ti­cat­ed tools the net­work uses in this effort also have more down-to-earth applications. 

USAEDS has sen­sors on Glob­al Posi­tion­ing Sys­tem and Defense Sup­port Sys­tem satel­lites that mon­i­tor space and Earth’s atmos­phere for light flash­es, radioac­tiv­i­ty and oth­er tell­tale signs of nuclear explosions. 

The system’s hydroa­coustic sen­sors are micro­phones that lis­ten for nuclear explo­sions under the sea. Infra­sound sen­sors mea­sure changes in the atmos­phere gen­er­at­ed by very-low-fre­quen­cy acoustic waves that can come from above-ground nuclear explosions. 

As part of the sys­tem, a WC-135 air­craft flies to the sites of explo­sions and col­lects air that sci­en­tists on the ground ana­lyze for radioac­tive par­ti­cles and radioac­tive gases. 

And the system’s 40 seis­mic sta­tions around the world — using the same tech­nol­o­gy sci­en­tists use to mea­sure earth­quakes — mon­i­tor the plan­et for under­ground nuclear explosions. 

“When nuclear test­ing was forced under­ground [in the 1970s], we had to switch over to more depen­dence on things like seis­mic sen­sors, and our seis­mic sta­tions start­ed to expand,” AFTAC chief sci­en­tist David O’Brien told Amer­i­can Forces Press Service. 

“Our first sta­tion was in Turkey, prob­a­bly in the late 1950s, prob­a­bly close to where the then-Sovi­et Union was test­ing [nuclear devices],” O’Brien said. “As time went on and more and more test­ing was going on under­ground,” he added, “we start­ed estab­lish­ing more of our over­seas sites.” 

Because of AFTAC’s crit­i­cal mis­sion to detect and report nuclear blasts, sys­tem sen­sors con­form to the high­est tech­ni­cal stan­dards and oper­ate day and night, 365 days a year. 

So if any­thing cat­a­clysmic hap­pens any­where on Earth — a large earth­quake, for exam­ple — the sys­tem knows about it. 

“If it’s a very large earth­quake, any­thing over about mag­ni­tude 6.0, we will noti­fy the U.S. Geo­log­i­cal Sur­vey, which is respon­si­ble for par­tic­i­pat­ing in the Inter­na­tion­al Tsuna­mi Ear­ly Warn­ing Sys­tem, O’Brien said. 

“This is not a nuclear explo­sion, this is an earth­quake [but] it’s large and it could be caus­ing a lot of dam­age so we will imme­di­ate­ly let the USGS know,” O’Brien said. 

“The USGS prob­a­bly has detect­ed it too,” he added, “but this aug­ments their infor­ma­tion as well.” 

The USGS Nation­al Earth­quake Infor­ma­tion Cen­ter in Col­orado has a domes­tic net­work of seis­mic sta­tions called the Advanced Nation­al Seis­mic Sys­tem, and it is part of an inter­na­tion­al sys­tem called the Glob­al Seis­mo­graph­ic Network. 

USGS, the U.S. Nation­al Sci­ence Foun­da­tion and an orga­ni­za­tion called the Incor­po­rat­ed Research Insti­tu­tions for Seis­mol­o­gy formed the inter­na­tion­al sys­tem, which has more than 150 seis­mic sta­tions around the world. 

The Pacif­ic Tsuna­mi Warn­ing Cen­ter in Hawaii, part of the U.S. Nation­al Ocean­ic and Atmos­pher­ic Admin­is­tra­tion, uses USGS seis­mic data and a range of sen­sors in oceans around the world to issue earth­quake and tsuna­mi warn­ings for Hawaii, Amer­i­can ter­ri­to­ries in the Pacif­ic, 25 coun­tries in the Pacif­ic Ocean basin, and the Indi­an Ocean region. 

But there’s a big dif­fer­ence between these ded­i­cat­ed dis­as­ter warn­ing sys­tems and AFTAC’s nuclear detec­tion network. 

“We install our sys­tems in areas where there is very low seis­mic noise,” O’Brien said. 

“The USGS may have their sta­tions close to cities where there’s lots of vibra­tion in the ground,” he said, or in areas like Cal­i­for­nia or New Zealand that have lots of seis­mic activity. 

“The USGS is real­ly look­ing for big earth­quakes,” the sci­en­tist added. “They don’t have the require­ments that we do — to look for very, very small explo­sions” that may occur under­ground dur­ing a nuclear test.” 

The U.S. Atom­ic Ener­gy Detec­tion Sys­tem looks for some­times-sub­tle indi­ca­tors of an atom­ic explo­sion, he said. 

“I can’t tell you how low we go,” he said, refer­ring to the low­est-lev­el mag­ni­tude the sys­tem can detect, “but we go very much low­er than a dis­as­ter net­work might go.” 

Unlike many dis­as­ter and research net­works, USAEDS runs 24 hours a day, sev­en days a week, 365 days a year, he said. 

“Data is con­tin­u­al­ly com­ing in, in real time from all these world­wide sen­sors. We ana­lyze data as soon as it comes into the build­ing,” O’Brien said. 

“Our respon­si­bil­i­ty is to pro­vide imme­di­ate noti­fi­ca­tion if an explo­sion occurs any­where in the world,” he said. 

Anoth­er net­work that, like the Defense Depart­ment, mon­i­tors for nuclear explo­sions but also detects nat­ur­al dis­as­ters is the Com­pre­hen­sive Test Ban Treaty Organization’s Inter­na­tion­al Mon­i­tor­ing System. 

The treaty opened for sig­na­ture in 1996 and is signed by most coun­tries in the world but not yet rat­i­fied by enough coun­tries to put the treaty into force. 

In the mean­time, the treaty orga­ni­za­tion, head­quar­tered in Vien­na, Aus­tria, is build­ing a glob­al net­work of sen­sors and oth­er pro­gram ele­ments that ulti­mate­ly will help enforce the treaty. 

AFTAC experts have advised the orga­ni­za­tion about build­ing its 337-facil­i­ty net­work, and both AFTAC and the Unit­ed States con­tribute data to the system. 

“The Unit­ed States is part of the Inter­na­tion­al Mon­i­tor­ing Sys­tem,” O’Brien said. 

“When we signed the treaty, which we have not rat­i­fied yet, we agreed to put sta­tions on U.S. soil to par­tic­i­pate in the sys­tem. That includes seis­mic and hydroa­coustic sta­tions,” he said. 

“Some of the sites we have in our USAEDS net­work also con­tribute to the IMS, he added, “but not all.” 

In for­eign coun­tries where USAEDS has estab­lished seis­mic sites, the Unit­ed States has agree­ments with those coun­tries, O’Brien explained. 

“Each coun­try can decide whether or not they want to con­tribute to the Inter­na­tion­al Mon­i­tor­ing Sys­tem” or any oth­er seis­mic net­work, he said. 

“We want the data, but whether they give it to some­body else or not, we don’t care,” O’Brien said, “although [shar­ing the data] cer­tain­ly ben­e­fits the Inter­na­tion­al Mon­i­tor­ing Sys­tem. That’s a pos­i­tive aspect.” 

In May, after a 9.0 mag­ni­tude earth­quake and tsuna­mi affect­ed hun­dreds of thou­sands of peo­ple and dam­aged the Fukushi­ma Daichi pow­er plant in Japan, USAEDS was pressed into ser­vice, the sci­en­tist said. 

The system’s seis­mic sta­tions “most cer­tain­ly detect­ed the earth­quake and many after­shocks,” O’Brien said, and the sys­tem was recruit­ed to sup­port U.S. efforts in response to the Japan­ese nuclear reac­tor accident. 

“We deployed our WC-135 air­craft to col­lect air over the ocean east of Japan to deter­mine radioac­tiv­i­ty lev­els there,” he said. 

Also in May, radionu­clide sen­sors that are part of the Inter­na­tion­al Mon­i­tor­ing Sys­tem picked up traces of radioac­tive par­ti­cles and gas­es from the strick­en pow­er plant. So far, more than 35 radionu­clide sta­tions have pro­vid­ed infor­ma­tion on the spread of radioac­tiv­i­ty from the Fukushi­ma accident. 

In addi­tion to its pri­ma­ry mis­sion, USAEDS also con­tributes to a U.S. pro­gram estab­lished through the Depart­ment of Home­land Secu­ri­ty after the Sept. 11 attacks on the World Trade Cen­ter and the Pen­ta­gon in 2001. 

“One thing the [new] Depart­ment of Home­land Secu­ri­ty had to address was the pos­si­bil­i­ty that a ter­ror­ist could det­o­nate a nuclear device in the Unit­ed States,” O’Brien said. 

The result, he said, was the Nation­al Tech­ni­cal Nuclear Foren­sics Pro­gram, an inter­a­gency effort that involves the depart­ments of Home­land Secu­ri­ty, Secu­ri­ty, Ener­gy and Jus­tice — pri­mar­i­ly the FBI — as well as the Defense Depart­ment and the intel­li­gence community. 

The team, O’Brien said, “would respond to a nuclear explo­sion in the Unit­ed States for the pur­pose of try­ing to deter­mine who did it. It’s called attribution.” 

In that effort, he added, USAEDS would use its air­craft to sam­ple radioac­tive debris. 

“The Army would do ground sam­pling,” O’Brien said, “but because we have been doing analy­sis on radioac­tive debris for many years and have lab­o­ra­to­ries in the Unit­ed States that sup­port us, we would over­see all the analy­sis of radioactivity.” 

Whether radioac­tiv­i­ty is detect­ed by the Depart­ment of Ener­gy or AFTAC’s air­craft or the FBI, the sci­en­tist said, “we would be the sin­gle point for the nation to do analy­sis of that debris for the attri­bu­tion process.” 

U.S. Depart­ment of Defense
Office of the Assis­tant Sec­re­tary of Defense (Pub­lic Affairs) 

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