The near 300-meter (980 ft) high SEG Plaza inexplicably began to shake at around 1pm, prompting an evacuation of people inside while pedestrians looked on open-mouthed from the streets outside.

Traffic resumed near the building by 6pm but it remained roped off.One of China's tallest skyscrapers was evacuated Tuesday after it began to shake, sending panicked shoppers scampering to safety in the southern city of Shenzhen. we all escaped with others by taking the stairs.' She told the South China Morning Post: 'The shaking didn’t seem strong from the 14th floor. Ji Jialin, who was on the 14th floor at the time of the swaying today, said the evacuation happened on her lunch break. 'SEG has been completely evacuated,' wrote one Weibo user in a caption to a video of hundreds of people milling about on a wide shopping street near the tower. It was not immediately clear how authorities will handle a dangerous building of its scale in the heart of a city of over 12 million people.īystander videos published by local media on Weibo showed the skyscraper shaking on its foundations as hundreds of terrified pedestrians ran away outside. 'The cause of the shaking is being verified by various departments.' 'After checking and analysing the data of various earthquake monitoring stations across the city, there was no earthquake in Shenzhen today,' the statement said. The local weather report showed a wind speed of 27mph at the time which should not have caused such an issue for the building. 'Judging from the currently available information, this could be an accidental frequency coincidence, that is, resonance.' He told the Shenzhen Special Zone Daily: 'If there was no earthquake today, it would be unusual for SEG Plaza to have such a situation. One theory shared by Lu Jianxin, a chief engineer at China Construction Science and Industry Corp, posits that the rare phenomenon was caused by mechanical resonance, which occurs when a structure's natural oscillations time up with an external force. The 79-storey building was sealed shut as of 2:40pm, according to local media reports.Ĭompleted in 2000, the tower is home to a major electronics market as well as various offices in the downtown of one of China's fastest-growing cities.Įmergency management officials are investigating what caused the tower in Shenzhen's Futian district to wobble, according to a post on the Twitter-like Weibo platform. No earthquakes have been recorded and authorities remain baffled as to what caused the motion. The 980ft SEG Plaza started swaying at 1pm on Tuesday in the southern city of Shenzhen, causing a mass exit from the building.

One of China's tallest skyscrapers has been evacuated after it mysteriously started to shake, sending panicked shoppers running to safety. Most structures have measures in place, including pendulums in large skyscrapers, to prevent such events occurring. Their synchronised movements matched the building's natural frequency, causing it to shake for 10 minutes before it settled. In 2011, a skyscraper in South Korea started to rock, and a later study by professors and building engineers found that a Tae-Bo exercise class on one floor with 17 people caused the motion. This has previously caused the collapse of bridges such as the Broughton Bridge across the River Irwell, the Angers Bridge disaster in France, and the swaying of the Millennium Bridge. This is why soldiers are often warned not to march in step on bridges because the frequency could match the structure's natural frequency. In buildings or on bridges, this can occur when people on or inside the structures, sync up their movement. This process, known as resonance, can cause one weak vibration to cause a big vibration on a larger object.Īn example on a small scale would be someone breaking a wine glass by singing at exactly the right note, its resonant frequency. When these structures are subjected to external vibrations or forces at a frequency equal or close to their natural frequency, these objects often vibrate very strongly. Structures and buildings have natural vibrations depending on their size and shape, which are not normally felt by passersby, known as their natural or resonant frequency. Vibrations inside the building could have coincided with the structure's internal movement, amplifying an effect known as resonance. Engineers are continuing to investigate the cause of the SEG Plaza's movements today, but one expert believes it could be due to an 'accidental frequency coincidence'.

China skyscraper wobbles