Abstract. The paper presents a methodology for the multi-hazard fragility analysis of fluvial earthen dikes in earthquake- and flood-prone areas due to liquefaction. The methodology has been applied for the area along the Rhine River reach and adjacent floodplains between the gauges at Andernach and Düsseldorf. Along this domain, the urban areas are partly protected by dikes, which may be prone to failure during exceptional floods and/or earthquakes. The fragility of the earthen dikes is analysed in terms of liquefaction potential, characterized by the factor of safety estimated using the procedure of Seed and Idriss (1971). Uncertainties in the geometrical and geotechnical dike parameters are considered in a Monte Carlo simulation (MCS). Failure probability of the earthen structures is presented in the form of a fragility surface as a function of both seismic hazard and hydrologic/hydraulic load.

Abstract. The paper presents a methodological framework for multi-hazard fragility analyses for fluvial earthen dikes in earthquake and flood prone areas. The methodology and results are an integral part of the multi-hazard (earthquake-flood) risk study implemented within the framework of the EU FP7 project MATRIX (New Multi-Hazard and Multi-Risk Assessment Methods for Europe) for the area around Cologne, Germany. The study area covers the Rhine River reach and adjacent floodplains between the gauges Andernach and Düsseldorf. Along this domain, the inhabited areas are partly protected by earthen embankments (dikes or levees), which may be prone to failure in case of exceptional floods and/or earthquakes. The main focus of the study is to consider the damage potential of the dikes within the context of the possible interaction between the two hazards. The fragility of the earthen dikes is analyzed in terms of liquefaction potential characterized by the factor of safety. Uncertainties in the geometrical and geotechnical dike parameters are considered by using a Monte Carlo approach. The damage potential of the earthen structures is presented in the form of a fragility surface showing the damage probability as a function of both seismic ground shaking and flood water level. The obtained results can be used for multi-hazard risk assessment in earthquake and flood prone areas and, in particular, are intended for comprehensive risk assessment in the area around the city of Cologne.