As many of you know, earlier this year on January 20, the fire department was called to investigate reports of severe tremors at Acro Seoul Forest, located in Seoul's Seongsu-dong, Seongdong-gu. 'Tower D' at Acro Seoul Forest, also nicknamed KWANGYA, is known for being home to SM Entertainment (floors 6~19), as well as Hyundai Glovis Co, Socar Company, plus additional floors of luxury residential units.

In order to determine the cause of tremors and other concerns raised by the building's occupants, the building owners (LB Asset Management) requested a formal analysis by the Architectural Institute of Korea. The team formed by the Architectural Institute launched an investigation for approximately 2 months, then recently reported their findings at a presentation involving the building's owners, as well as representatives of each corporation.

The investigation team, led by professor Lee Sang Hyun from the department of architecture at Dankook University, presented the following conclusion as the cause of the tremors at 'Tower D': "Increased amplitude caused by concentrated, rhythmic group movement."

According to the investigation, the tremors were not caused by external forces such as strong winds, earthquakes, or nearby construction. The investigation team then carried out vibration experiments throughout the building and determined that resonance was detected on several floors when concentrated feet drumming occurred for over 30 seconds.

As shown in the chart below, the investigation team found that the greatest vibration activity occurred on floors 9 and 10, which houses practice rooms of various SM Entertainment artists. (Practice rooms are also located on floors 11 and 18.)

Finally, the investigation team concluded, "The tremors are caused by SM Entertainment artists or trainees performing synchronized choreography, causing a resonance effect throughout the building. There are no concerns involving safety or related to the architectural design and construction method. Overall, the building is stable. However, we recommend installing devices which can control large vibrations."