Analogue experiments investigate how flank collapse affects dike propagation within volcanoes. Water (magma analogue) is injected within a gelatin cone (volcano analogue) with a lateral collapse. The injections form dikes that, away from the collapse, become radial. The dikes propagating nearby the collapse focus towards the collapse sides, becoming subparallel to them, because of the stress reorientation due to the unbuttressing. Only dikes formed along the collapse axis (passing through the mean points of the collapse, map view) propagate radially within the collapse. This general model is applied at Stromboli. The Stromboli dikes cluster along and parallel to the collapse sides, similar to the experiments. Nevertheless, the current location of the conduit, along the collapse axis, leads to dike propagation within the collapse infill, rather than at its sides. This may have occurred during the 2002--03 eruption, when diking in the collapse triggered a landslide and tsunami within the collapse.