Bearing in mind the destructive potential of tsunamis induced by volcanic landslides, the tsunamigenic event occurring at Stromboli volcano in Italy on 30 December 2002 has been re-examined here, by means of visible images and slope stability analysis. This was one of the few examples in the world of a flank collapse occurring at a volcano that was directly observed. We present the results of stability analyses, together with a sequence of photos collected from a helicopter a few minutes before the collapse. The result of this study is that the sequence of landslides triggering the 2002 Stromboli tsunami can be defined as the final stage of a lateral magma intrusion that exerted a high thrust at high altitude, destabilizing the entire slope. This study allows a more complete understanding of the event that took place on Stromboli on 30 December 2002. Furthermore, the approach used here, if appropriately modified, can be used in other contexts, contributing to the understanding of the condition that leads to tsunamigenic landslides.