The stability of municipal solid waste (MSW) landfills is a significant environmental concern. The performance of
landfills during earthquakes should be evaluated to ensure their stability. The geometry and material types of MSW
landfills are the main factors affecting their seismic response. In this study, the individual and coupled impact of
these factors is investigated using numerical analyses. Amplification factors (AFs = Accsurface/Accbase) are investigated
for six common MSW landfill types, namely canyon type, hill type, side-hill types 1 and 2 and stepped-base types 1
and 2. The results show that landfill types have significantly different behaviours due to their geometry and
waste material properties. For low stiffness contrasts, the stepped-base landfill type has the minimum and the hill
type experiences the maximum AF, 1.74 and 3.53, respectively. However, for high stiffness contrasts, the canyon
type has the minimum AF (0.46) due to the effect of damping and thickness of the waste. Therefore, the proper
geometry of the MSW landfills should be designed for specific waste material properties according to the seismic
response.