Earthquake Natech risk assessment, monitoring and management of cylindrical liquid storage tanks with floating roof in major-hazard industrial plants

Earthquake is one of the natural events which is part of NaTech events (Natural Hazard Triggering Technological Disasters), due to interaction between natural and industrial risks. Industrial plants employ cylindrical liquid tanks with floating roof for storage of volatile and flammable products. Damages due to earthquakes affecting tanks with floating roof can cause major accidents involving dangerous substances, like hazardous releases, fires and explosions, especially due to the convective motion of the fluid caused by seismic excitation. The aim of this work is to inform about the most common damages in case of seismic event and to give some advice to seismic risk management through monitoring of critical elements of liquid storage tanks with floating roof. During an earthquake, damages to structural and non-structural elements can occur, and the non-structural elements are often the most involved in major accidents. In order to mitigate the consequences of a major accident, a monitoring system of the tank for management of the seismic risk can be installed, integrating new dedicated sensors into the existing monitoring network. The fiber optic sensors FBG (Fiber Bragg Grating) and FSI (Fiber Segment Interferometry) are a robust, multifunctional and removable alternative to the sensors already in use in the industrial field.