Activities with potentially (very) large accidents require (very) small probabilities. Modelling such rare phenomena is challenging and the accuracy is quickly questioned. Too little support unnecessarily holds back new activities, produces inexplicable differences in regulation, causes great unrest after an accident, and creates disproportionate precautionary measures. Use of the subsurface after the Groningen earthquake problem is a current example.

The lecture by our KIVI member Johan de Knijff deals with uncertainty of the model itself. It is not easy to quantify lack of knowledge in a risk analysis, in contrast to the well-stocked toolbox for observable phenomena. As an illustration surprises at LNG tanks: it took half a century for a special but catastrophic storage failure to become sufficiently clear for adequate action. Model uncertainty thus puts a limit on small probabilities and hence usability. For existing, but altogether for future situations. For example, induced earthquakes are a new risk with geothermal energy in ... South Holland.

Consider that in the Netherlands a model should be able to work with values as low as once per million years, a common limit and not even the lowest number used in risk analyses. Cases with great tension between probability and model confidence are therefore up for grabs. I will draw from these to end with some developments from the risk field towards quantified model confidence. The audience will then be able to judge, example by example, whether the probability of an incorrect model has been adequately handled. And hopefully have become a little more aware of risk management that exists only on paper.

SPREKER
Johan de Knijff graduated in large-scale accident risks, has worked as an independent consultant carrying out risk analyses since 1996, and continues to research risk concepts in practice. More information can be found at https://sites.google.com/site/ejestro/, including a contribution on risk tools against stagnant management from "De Ingenieur".

Drinks will commence at 18:00 and the meal will follow punctually at 19:00, after which the lecture can start at 20:00.

Further information or registration can be obtained via: kringrotterdam@kivi.nl

Please note that a payment link to pay the participation fee will be sent in advance.