The more than 70-storey SEG Plaza skyscraper in Shenzhen, China is known as a bustling gathering place for electronics manufacturers across the country. This place has now been closed for a comprehensive inspection after the fierce shaking and chaos on May 18 that caused thousands of people to panic and flee.
A preliminary investigation shows that the combination of three factors including wind, the metro line under the SEG Plaza, and the temperature difference inside and outside the building, is likely to contribute to the phenomenon of aerodynamics that experts call the "Karman tournament" that caused the incident, according to a report from the China Securities Journal.
However, there has been no official explanation for the shocking incident. Shenzhen Electronics Group - owner of SEG Plaza - has not commented while the Quangzhou Emergency Management Department also declined to speculate on the cause of the incident.
Previously, the building management issued an internal notice requesting that from the morning of May 21, no one was allowed to enter or exit the building until the investigation was completed and there was no specific time frame.
However, by the afternoon of May 21, traders had moved the goods out of the building.
Business in the area around the SEG Plaza and traffic have returned to normal and the building is now a popular spot for taking photos for fun.
The Karman spiral is a repeating model of spiral caused by the separation of liquid or wind around a certain structure. This is considered the cause of the sudden collapse in 1940 of the Tacoma Narrows bridge in Washington state, northeast of the US.
In 1965, the Ferrybridge coal plant in England also caught fire after three of its eight cooling towers began to shake before collapsing.
A 2001 paper by graduate student Jin Dianqi - now a senior engineer - attracted public attention after it was discovered that the technical drawings of the SEG Plaza building were actually behind in construction, according to a report by Chinese media outlet - The Securities Times. The author believes that the design of the building was changed during construction, and an entrance to the roof had to be replaced due to a mistake during the design stage.
According to the Council on skyscrapers and Urban Environment (CTBUH) - a Chicago-based organization specializing in high-rise design and construction - China has a total of 2,395 buildings over 150m high, the largest in the world, followed by the US with 825 buildings.
To date, China owns half of the world's top 10 skyscrapers and accounts for 44 of the world's top 100. Including the Shanghai Tower with 128 floors and 632m - the second tallest in the world. SEG Plaza is the 18th tallest building in Shenzhen and the 212th in the world, CTBUH data said.
