Bangkok: The president of the Engineering Association has analyzed that the collapse of the entire Aeon Mall building in Japan may have been caused by a ruptured gas pipe.
According to Thai News Agency, Professor Dr. Amorn Pimanamas, President of the Structural Engineers Association of Thailand and a professor at the Faculty of Engineering, Kasetsart University, stated that the 6.8 magnitude earthquake at a depth of 10 km in Kumamoto Prefecture, Japan, is believed to be a strike-slip earthquake occurring near the Futagawa and Hinagu fault lines.
Regarding the AEON Mall collapse, Professor Dr. Amorn noted that the collapsed AEON Mall was a two-story building. Examination of the collapse images reveals that it occurred on the second floor, approximately an hour and a half after the earthquake. The collapse pattern does not resemble typical earthquake collapses. Normally, if a low-rise building collapses due to earthquake shear force, the collapse occurs at the lower floors (where the shear force is highest), causing the lower floor columns to break, the building to tilt, or resulting in "soft storeys" and ultimately the entire building to collapse.
However, at AEON Mall, the collapse occurred on the second floor. The roof structure was damaged, the exterior walls were completely blown off, and the steel frame was severely warped and deformed. Witnesses reported seeing smoke and hearing an explosion, which may have been caused by a gas leak, such as liquefied petroleum gas (LPG), in the building's piping system. The Japanese authorities will need to investigate the true cause further.
Professor Dr. Amorn further commented that if the explosion was indeed caused by a gas leak, the building's piping system would need to be reviewed to determine its earthquake resistance standards and the presence of an automatic gas shut-off system. Even if the building didn't collapse due to an earthquake, a ruptured gas pipe could still cause an explosion and lead to the building's collapse.
Dr. Amorn concluded by saying that the AEON Mall building had previously suffered significant damage from the Kumamoto earthquake in 2016.