A coupling system provides a controlled decoupling of interconnected component sections of a marine platform structure less rigid under seismic shock while maintaining sufficient overall ridigity to resist the action of swell. The coupling system comprises rigid interconnecting linkage parts, such as steel supports, and flexible interconnecting members, such as "Neoprene" supports, incorporated in the structure. The rigid linkage parts have a structural ridigity sufficient to maintain the overall rigidity of the platform but are effective to break following a seismic shock. The flexible interconnecting members are held in reserve and arranged to back up the rigid integrating parts. The flexible members have structural characteristics effective to maintain the controlled decoupling of the component sections when the steel supports deform or break. The coupling system providing the controlled decoupling is located at an upper level of the structure, preferably above water level, for ease of repair.