the fjord, the buoyancy chambers imploded and the rubble struck the floor of the fjord, creating a Richter magnitude scale 3 earthquake. Later analysis showed that the failure would occur at 62 meters (203 feet). No one was injured during the accident. Investigation The post-accident investigation by SINTEF in Norway discovered that the root cause of the failure resulted from inaccurate NASTRAN calculations in the design of the structure. Stresses on the ballast chambers were underestimated by 47% and some concrete walls were designed too thin to resist foreseeable hydrostatic pressure when submerged. As the pressure increased, the walls failed and cracked, allowing sea water to enter the tank at an uncontrolled rate, eventually sinking the hull. After the accident, the project leaders from Norwegian Contractors were brought before the Statoil board, and were expecting severe repercussions. But the director instead asked the famous question "Can you make a new one before schedule?" to which the contractors replied "Yes we can". The new hull was completed before schedule. Computer-Aided Catastrophes Computer-Aided Catastrophes, or CAC for short, such as the Sleipner Incident presented in this article, provide extremely valuable lessons for practising engineers working with numerical simulation tools such as the finite element method. The reason for the poor finite element result that led to the Sleipner Incident have been studied in more detail in NAFEMS Benchmark Challenge Number 6. References Natural gas platforms Natural gas industry in Norway Collapsed oil platforms History of the North Sea North Sea energy Maritime incidents in 1991