A novel multiple-expert protocol to manage uncertainty and subjective choices in probabilistic single and multi-hazard risk analyses

Integrating diverse expert opinions in hazard and risk projects is essential to managing subjective
decisions and quantifying uncertainty to produce stable and trustworthy results. A structured
procedure is necessary to organize the gathering of experts' opinions while ensuring transparency,
accountability, and independence in judgements. We propose a novel Multiple-Expert
management Protocol (MEP) to address this challenge, providing procedural guidelines for conducting
single to multi-hazard risk analyses. MEP establishes a workflow to manage subjectivity
rooted in (i) moderated and staged group interactions, (ii) trackable blind advice through written
elicitations with mathematical aggregation, (iii) participatory independent review, (iv) close cooperation
between scientific and managerial coordination, and (v) proper and comprehensive
documentation. Originally developed for stress testing critical infrastructure, MEP is designed as
a single, flexible, technology-neutral procedural workflow applicable to various sectors. Moreover,
its scalability allows it to adapt from high to low-budget projects and from complex probabilistic
multi-hazard risk assessments to standard single-hazard analyses, with different experts'
degree and type of involvement depending on available funding and emerging controversies. We
present two compelling case studies to showcase MEP's practical applicability: a multi-hazard risk
analysis for a port infrastructure and a single-hazard regional tsunami hazard assessment.