Natural disasters can trigger technological disasters. Many technological facilities such as fuel storage plants, chemical plants, power generation plants, etc., are located in natural hazard-prone areas. A natural event triggering a technological disaster is usually called NaTech, and can pose tremendous risks to regions which are unprepared for such events.

The United Nations Office for Disaster Risk Reduction has carried out extensive work to stress the importance of such events, as well as to draw the attention on preparedness and resilience to this kind of disasters. The most frequent natural events that cause technological disasters are extreme rainfall, floods, extreme winds and earthquake. The potential consequences for technological plants or systems span a very wide range. Some examples are release of hazardous material, damage to oil and gas pipelines, damage to lifeline systems, etc.

RED has carried out an accurate NaTech risk assessment analysis for a large fuel storage facility located in Italy, to analyse the risk and possible consequences of a technological disaster triggered by flooding. The risk analysis has been carried out in three steps:

• Hazard assessment;
• Vulnerability assessment;
• Consequence analysis;

The hazard assessment has been carried out by analysing the observed values of maximum wind at nearby stations, to obtain a probability distribution of the extreme wind speed. The vulnerability assessment has been carried out by analysing several possible mechanisms of failure for all the components of the plan (tanks, puming systems, pools, etc.) to obtain vulnerability curves. The possible consequences have been assessed using a consequence tree which combines the failure of several components of the plan. The final result is the estimation of the probability fo different types of consequences, including the release of hazardous material into the surface or sub-surface water bodies.