The losses caused by natural disasters may significantly increase when different hazards occur simultaneously or over a short period of time. Classes of interactions among the different perils include triggered events, cascade effects, and rapid increases of vulnerability during successive extreme events. For example, higher wind speeds in combination with moderate precipitation near the freezing temperature caused heavy ice load on high-tension power lines leading to the collapse of various masts and, consequently, to a total blackout over several days in the Emsland in 2005.

The EC Project MATRIX will integrate new methods for multi-type assessment, accounting for risk comparability, cascading hazards, and time-dependent vulnerability. MATRIX will identify the conditions under which the synoptic view provides significantly different and better results- or potentially worse results-than established methods for single-type hazard and risk analysis. The MATRIX consortium draws together a wide range of expertise related to many of the most important hazards for Europe (earthquakes, landslides, volcanic eruptions, tsunamis, wildfires, winter storms, and both fluvial and coastal floods), as well as expertise on risk governance and decision-making.

Within the frame of MATRIX, IMK will assess and quantify the hazard related to synoptic-scale wind storms, heavy precipitation, and heat/cold waves for the test regions of Cologne and Naples. In the first step, the different perils will be considered as independent and treated separately. In the next step, we will examine the temporal succession and persistency of the relevant weather systems and the probability of coincidence of different extremes. The results and lessons learned can be applied to a so-called "virtual city" to estimate the interrelationship and non-linear amplification processes of the different perils and their impacts.