"The assessment of natural hazards is of the uttermost importance but because of its multidisciplinary rarely manages to incorporate all the relevant strands of evidence. Several mathematical formalisms have been proposed (including for instance Bayesian Belief Networks and Event trees) but the problem of ""filling"" these formalisms with data, knowledge and especially of fully taking into account the ""human dimension"" of the necessary multidisciplinarity remains widely open. In order to tackle this problem we propose a three-way staff exchange program between the University of Udine, Italy, the National Museum of Natural Sciences, Madrid, Spain, and St. Petersburg State University, Russia. Over the last years these three institutions have been collaborating on topics related to natural hazard assessment. The University of Udine has a long record of joint work with the National Museum of Natural Sciences in Madrid mainly devoted to volcanic hazard, but site effects, and the corresponding risk assessment, are assuming growing importance in the collaboration. Lately, a new formalism for risk assessment, based on both logical and probabilistic inference, has emerged as a result of collaboration between St. Petersburg State University and the University of Udine. This formalism is a step ahead from Bayesian Belief Networks, and is currently one of the major advances in probabilistic risk assessment. The staff exchange program should empower our mutual collaboration and make the ongoing research a success. We plan mutual visits between all participating institutions. Scientifically, we intend to unite the site effects research and geophysical considerations developed in Madrid and Udine with the logical and probabilistic framework developed in St. Petersburg. The three institutions have exceptionally qualified researchers, and their mutual synergies have already been established through a long history of joint publications."