Concern about hazards that volcanic plumes pose, especially to aviation safety, has led scientists for about two decades to using satellite sensors in different wavelengths for the detection and study of volcanic activity. Together with ground-based meteorological radars, these techniques now enable tracking the ascent and dispersal of large eruptive clouds, making reflectivity mapping, determining plume heights, measuring gas (SO2) and aerosols content, and estimating particle sizes and total mass of gas and fine ash Harris and Rose, 1983>. However, there is still a crucial need for direct measurements of particle velocities, especially near an emission vent, to constrain physical and numerical models of eruption dynamics, which in turn, should improve our predictive capacity regarding plume behavior.