Subaerial landslides falling into reservoirs or open seas generate impulsive water waves, that are usually referred to as a class of tsunami waves. It is important to study landslide-generated waves occurring both in closed water basins, where the waves interact with the shorelines and eventually the dam, and in open seas, where the generated waves can travel and deliver devastating damages hundreds of kilometers away. In order to gain insight on subaerial landslide generated waves, the Italian National Dam Office recently funded an experimental and numerical research program geared to better understand and forecast tsunamis waves. This paper introduces the experimental work which has been carried out in order to define empirical formulations able to forecast the principal features of the generated waves in a three-dimensional water body, as a function of the landslide movement. Wave types observed during the experiments are here characterized using a wavelet analysis approach; new forecasting formulations (named RID formulas) are defined on the basis of the experimental study and tested using an artificial neural network model. Results are finally compared to those presented in past experimental studies.