How many Tae Bo'ers does it take to
screw in a lightbulb make an entire building tremble in fear? Exactly 23—just about the same number of students present in public school classrooms in well-heeled Connecticut towns. According to the Korea Times, a Tae Bo class on the 12th floor of the 39-story Techno-Mart shopping mall in Seoul, South Korea, made the whole building shake, causing a full-fledged investigation as to why. In not-so-plain speak, vibrations caused by the exercises matched the resonance frequency of the building: "When an external vibration hits the resonance frequency of a certain object, the vibration is amplified and causes excess shaking even from slight movement." (Imagine a giant tuning fork.) Said one architecture professor: “The new fitness instructor apparently carried out the exercise twice as hard as usual. That must have been the reason." Regardless, quivers were so strong that hundreds of people fled.
· Aerobic exercise blamed for tremor at Techno-Mart [Korea Times via Gizmodo]
· Hundreds flee shaking Seoul shopping mall [Xinhuanet]