A mega-tsunami (run up height : 6 m), caused by a major earthquake (Mw = 9, the great Tohoku earthquake), striked at 2:54 pm a cement plant located in an port. Since the foreshocks occurrence at 2:46 pm, the 156 employees had been evacuated and the facilities put in a safe state. The lower part of the complex was flooded under 5-6 meters of seawater, causing extensive damage but no casualties. A bulk carrier ship berthed at the cement loading wharf had time to cast off before the tsunami and sucessfully faced the waves as they arrived into the port. The fuel tanks feeding the rotary kilns, waste incineration and bulk raw materials (clay, silica … ) storages located on the seafront were swept away by the tsunami. One of the two rotary kilns, the lower one, was flooded. A portion of the port infrastructure was destroyed : docks and unloading cranes, silos and warehouses, electric lines and stations , rail infrastructure linking the site to a limestone extraction area. A road relief convoy sent by the head office arrived on site 6 days after the disaster with food and equipment repair. The amount of damage is estimated at 92 million of euros (2011). The upper rotary kiln was restarted after two months and its facilities were modified to be able to burn the waste generated by the tsunami in the region after desalination. Cement production resumed after 8 months, and 1 month later the lower rorary kiln was restarted to increase the capacity of tsunami waste incineration.