Mystery shaking brings Shenzhen tower jitters

A Shenzhen skyscraper shook mysteriously for a second day yesterday as daring tenants reentered the building.

Around 15,000 tenants and passersby were sent fleeing as the 72-story SEG Plaza in Huaqiangbei shook for no apparent reason on Tuesday.

Authorities banned outsiders from entering the skyscraper, but tenants were allowed to go in to get their belongings. Tenants of many lower floors were busily handling goods when they noticed the skyscraper was shaking again yesterday between 1.30pm and 2pm.

This was despite an expert team determining the building to be structurally safe by monitoring various locations for their settlement and vibrations.

“Testing is being carried out. According to preliminary investigations, the building’s major structure is safe,” Shenzhen SEG, which manages the SEG Plaza, told tenants yesterday.

All tenants were evacuated at 1.55pm on Tuesday and experts were deployed to carry out preliminary inspection.

“They did not find cracks on the ground, nor boards detached from the skyscraper’s walls … Other details and causes behind the incident are still being investigated,” it stated.

Tenants who entered the building yesterday said they had few choices and were not that worried about their safety.

“Customers have placed their orders and we need to come back to get the products distributed,” said a shop owner working on the fourth floor.

Another operator on the 25th floor said the property management office required tenants to promptly leave once they completed their emergency tasks at hand.

Authorities have ruled out an earthquake or a typhoon as a possible cause and reasoned the building shook due to its own structure.

According to Hao Shaobo, an associate professor at the Huazhong University of Science and Technology’s School of Architecture and Urban Planning, architects would have taken shaking into account when they designed and built skyscrapers.

“The higher the building is, the more obvious the shaking will be, which is known as the whipping effect,” Hao said.

He said a device that slows down the shaking – known as a shock absorber – was usually placed near the top of skyscrapers.

“The shock absorber will swing in the opposite direction of the building to cancel out the shaking so that it helps the building maintain balance,” he said.

An architectural expert said it was normal for high-rise buildings to shake due to the airflow high above, and people need not be worried.