By Birgit Bürkner
After 1,100 hours of engineering work, the expert Dr. Christian Bonten (54) investigates the causes of the Aquadom bursting. How was the mystery solved? He checked all possible scenarios for their probability.
Did pistol shots destroy the 16 meter tall acrylic gas cylinder? “The glass was more than twenty centimeters thick and more than bulletproof,” says Bonten. Unlikely! “If several bullets had been fired at the same spot, hotel guests would have noticed it.” The room windows of the Radisson Blu face the atrium in which the aquarium was located. No bullet casings were found and no noise detection dogs were used.
Has the glass been damaged with a sharp object, such as an ice pick? According to the plastics expert, the first crack appeared in the middle, i.e. on the belly, of the 16 meter high pool. “Someone would have had to abseil or put down a ladder to do this. That would have been noticed too.”
Complete chaos: This is what it looked like in the hotel the morning after the explosion Photo: Eleonora Dziambor
Did vibrations break the glass wall? Buses, trucks and a tram line pass in the immediate vicinity and a subway line crosses at a distance of 200 meters. “The sensors distributed throughout the building detected the normal vibrations. They are far away from critical values,” says Bonten. The new construction of the U-5 extension (2010 to 2020) would not have had a negative impact – the ground was too muddy. No earthquake could be detected using seismography either.
Did the concrete plate on which the Aquadom was attached sink? Bonten had it measured. “It hasn’t moved a millimeter since it was installed.”
The destroyed cylinder of the Aquadome and remnants of the acrylic cladding can be seen in the hotel lobby five weeks after the large aquarium burst Photo: dpa
Do the wrong cleaning agents affect the glass? Bonten: “Divers checked it every day. They would have recognized streaks and external cracks.”
Did temperature fluctuations cause the glass to crack? The night before the accident, the outside temperature was minus seven degrees: “No, the temperature in the atrium was 21 degrees throughout,” says Bonten.
Material fatigue? Tear tests and molecular laboratory examinations of the debris showed that the material was in top condition even after almost twenty years.
Was the aquarium simply constructed incorrectly? According to measurements, everything is perfect for the water weight of one million kilograms.
Was there any damage during construction work? Possible! During the renovation of the base due to a defective seal in 2019/2020, workers demonstrably knocked off the mortar collar with a hammer and chisel! “Wedges could have been carved into the glass at the foot of the aquarium,” says Bonten. “In addition, the pool was improperly left without water for four and a half months and the glass dried out. It is very likely that cracks formed and slowly propagated upward until a glue seam opened.”
On December 16, 2022, at 5:43 a.m., the Aquadome burst. A million liters of water containing around 1,500 tropical fish poured into the hotel lobby and surrounding streets, leaving two people slightly injured.