The wobbling of a skyscraper in the Chinese city of Shenzhen was likely caused by a combination of winds, underground rail lines, and fluctuating temperatures, according to preliminary findings reported by local media.
The near-300m-high (980ft) SEG Plaza first began shaking on Tuesday afternoon, prompting an evacuation of people inside while pedestrians looked on in horror.
There were no earthquakes in the area and local authorities said engineers had not found any safety abnormalities in the building or surrounding environment. Nor did the level of movement exceed building code limits.
Chinese media said a preliminary investigation, confirmed by the department of emergency management of Guangdong province, had found the wobbling was vertical rather than horizontal and that it was caused by a combination of winds, two underground rail lines under the building and the stretch of the steel caused by the rising temperature. The preliminary findings reportedly noted the building does not have a tuned mass damper – a huge pendulum-like device to prevent excessive swaying.
Meanwhile management of the building rejected reports that it started wobbling for a second time on Wednesday.
The 21-year-old building was sealed off to the public but some vendors went back inside to retrieve items. On Wednesday afternoon Jimu News reported two separate vendors said they felt the building shake again. A spokesman for Shenzhen SEG, the building’s developer, later denied this, telling reporters management had confirmed no further shaking.
Bystander videos published by local media on Weibo showed the skyscraper shaking as hundreds of terrified pedestrians ran away outside.
The building is named after the semiconductor and electronics manufacturer Shenzhen Electronics Group, whose offices are based in the complex.
It is the 18th tallest tower in Shenzhen, according to the Council on Tall Buildings and Urban Habitat skyscraper database. Building collapses are not rare in China, where lax building standards and breakneck urbanisation lead to constructions being thrown up in haste.
Authorities were yet to say when or if the building would reopen.
“They claim the building is safe. but I bet it will be nerve-racking entering the building,” said one commenter on Weibo.
Others expressed anger, suggesting the government department should move their office to the building, while some urged patience.
“They say ‘some further investigations are needed’. So stop asking and leave them some time. You want some solid conclusions instead of something that was made up, don’t you?”