Various past geological events have shown that landslides involving large volumes, up to several cubic kilometers, can happen near coastlines. These events may lead to tsunami waves of large amplitudes with important potential damages to infrastructure and populations. To better assess the associated hazards, one fundamental issue is to provide a deep understanding of the tsunami wave generation taking into account the granular nature of landslides. We investigate here the wave generation that followed the collapse of an initial vertical granular column in a small-scale laboratory experiment, with both water and granular interface tracking.