July 19th, 2011
07:51 AM ET

Scientist: Tae Bo workout sent skyscraper shaking

Seventeen people performing a vigorous Tae Bo workout caused tremors that forced the evacuation of a South Korean skyscraper earlier this month, the building's owners say.

Prime Group, owner of the 39-story TechnoMart commercial-residential high-rise in Seoul, said 17 middle-aged people were working out to the pop song "The Power" by Snap on July 5 when their movements set the upper floors of the tower shaking for 10 minutes, according to a report from the Korea JoongAng Daily.

Scientists recreated the event in the 12th floor gym, according to a report in the Korea Times.

“We observed the vibrometer while performing the same kind of aerobic exercise that was performed at the time of the shaking which occurred on July 5. We noticed that the shaking was felt in the upper floors while the exercise was being performed while no other place showed signs of tremor,” Chung Lan, a professor of architectural engineering at Dankook University, told the Korea Times.

“It just happens to be that the vibration cycle caused by Tae Bo collided with the vertical vibration cycle unique to the building,” Chung told the Korea Times. The action amplified the building's vibration and caused the shaking, he said.

Chung was one of six professors from the Architectural Institute of Korea who inspected the building and recreated the Tae Bo exercise.

Tae Bo is a mixture of boxing and tae kwon do.

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Filed under: South Korea • World
soundoff (322 Responses)
  1. Adam


    July 19, 2011 at 2:30 pm | Report abuse |
  2. Steve

    Modern towers are often built "on the cheap" these days. It's not surprising that the World Trade towers collapsed as easily as they did.

    July 19, 2011 at 2:33 pm | Report abuse |
    • NsRhea

      Because a Tae Bow exercise and a Jet Liner loaded with 200 people in it crashing into the side of the tower are pretty much the same thing, right?

      July 19, 2011 at 2:41 pm | Report abuse |
    • Nocordoba

      They didn't collapse easily they got hit (in effect) by 2 cruise missiles loaded with explosives (the fuel in the jets). The driver is the computer the fuel the war head and the people the target. Yep basic cruise missile.

      July 19, 2011 at 2:42 pm | Report abuse |
    • Guest

      They collapsed because there were thousands of gallons of jet fuel literally melting the support beams after the fire retardant was blown off.

      July 19, 2011 at 2:45 pm | Report abuse |
    • Steamr

      Pretty sure the designers of the original WTC Twin Towers never envisioned fully-fueled jets being DELIBERATELY into them. (A possibility that HAS been taken into account of the heavily-reenforced Freedom Tower).

      The phenomenon described here is harmonic resonance; it's why soldiers "break step" when marching across bridges. Doesn't have to caused by human foot-stomping either; Google "Tacoma Narrows Bridge", which was destroyed by resonance inducing swing into the bridge deck at specific wind speeds (should be able to find video of the collapse on YouTube). 😉

      July 19, 2011 at 2:46 pm | Report abuse |
    • iamthefredman

      Hello Steve Dipschitz,

      You are comparing WTC hit by 300MPH jetliners to 17 old people doing the cha-cha? You are really an ACE HOLE.

      July 19, 2011 at 2:51 pm | Report abuse |
    • Me

      You, Sir, are an idiot.

      July 19, 2011 at 2:55 pm | Report abuse |
    • tourguide

      Actually, Korean people were impressed by how well the World Trade towers well built when they were hit by jets in 911.

      July 19, 2011 at 2:56 pm | Report abuse |
    • Linda Lou

      What a stupid statement. How much could 15 Koreans weigh, as opposed to a jet liner loaded with people, their belongings, and jet fuel. Sounds like an even trade-off to me.

      July 19, 2011 at 2:57 pm | Report abuse |
    • Me

      "They collapsed because their support beams had timed explosives installed by a "security" firm owned by the brother of then US President George W. Bush."

      Yeah, and I suppose he had them put the explosives there in 1972 when the trade towers were finished so they could detonate them about 30 years later when he had a vision that his brother would be the president and we would be fighting terrorism too.

      July 19, 2011 at 3:09 pm | Report abuse |
    • 2bits

      No most towers in Asia are built with vibration dampeners for earthquake protection.

      But either this one didn't have those or if it did, they hit a magic frequency which wasn't engineered well and so it responded by resonating to that frequency. It's either bad engineering or bad planning (no quake dampeners). Either way it should be embarrassing to the South Koreans.

      July 19, 2011 at 3:13 pm | Report abuse |
    • Alex

      You are a moron.

      July 19, 2011 at 3:19 pm | Report abuse |
  3. sparta


    July 19, 2011 at 2:35 pm | Report abuse |
  4. Michael

    Yes, Nicola Tesla did discover he could collapse a building with small vibrations at resonant frequency.
    Soldiers break rank when marching across bridges to not hit resonant frequency.
    Galloping Gurdy/Gertie (Tacoma Narrows bridge) bridge collapsed due to having a resonant frequency.
    Univ of Illinois marching band had to stop playing Indian dance at football games because the people stomping in the upper bleachers caused it to sway.
    The wall of Jericho collapsed after Joshua marched the people around the walls.

    July 19, 2011 at 2:38 pm | Report abuse |
    • OvernOut

      Walkway at the Hyatt Regency collapsed in 1981–was it in St. Louis?–from people swaying to swing band music.

      July 19, 2011 at 3:23 pm | Report abuse |
    • OvernOut

      Looked it up, it was Kansas City, 114 people were lost.

      July 19, 2011 at 3:25 pm | Report abuse |
  5. Gung Ho

    Shake Rattle and Rock & Roll

    July 19, 2011 at 2:44 pm | Report abuse |
  6. FrauSchmitd

    Now I know how the Jericho walls fell.......

    July 19, 2011 at 2:50 pm | Report abuse |
  7. Kani

    They need to stop making buildings out of cardboard.

    July 19, 2011 at 2:51 pm | Report abuse |
  8. CommonSense

    Come on...surely this must be Obama's fault, no????

    July 19, 2011 at 2:52 pm | Report abuse |
    • 2bits

      If Obama resonated at the same frequency you could say that.

      But Obama only resonates on his own personal frequency that pads his ego.

      It grows and grows and grows and like any bubble it's going to burst someday.

      July 19, 2011 at 3:10 pm | Report abuse |
  9. Keyser

    Phase two of AL Queada.....Hi-Ya!

    July 19, 2011 at 2:54 pm | Report abuse |
    • f

      Al-Queads next planof attack. Get millions of Asians to do the boogi-woogie at the same time in a city and knock down many buildings ! Yeah, that might work.

      July 19, 2011 at 6:09 pm | Report abuse |
  10. KL

    CNN has it all wrong: Chuck Norris had a muscle spasm....

    July 19, 2011 at 2:55 pm | Report abuse |
  11. Fiona

    There was a similar event when the Twin Towers were being built. before the top was closed off on on of them, a party was given on the top floor. The building shook and swayed. Look what happened to those buildings. I'd stay out of that Koean tower.

    July 19, 2011 at 3:08 pm | Report abuse |
  12. winky70

    "I Got the Power!"

    July 19, 2011 at 3:08 pm | Report abuse |
  13. sammygreene

    A perfect example of "the resonator" that Deborah Shlian and Linda Reid wrote about in the exciting thriller "Devil Wind".

    July 19, 2011 at 3:08 pm | Report abuse |
  14. mag

    I would sue the architects for designing such as ridiculous building.

    July 19, 2011 at 3:09 pm | Report abuse |
  15. 2bits

    That's called 'Resonance' for those non-scientific types with no science knowledge.

    The same forces tore down a bridge in Washington decades ago. It swung higher and higher like a swing in the wind and boom down it came.

    July 19, 2011 at 3:09 pm | Report abuse |
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