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Red supergiant stars (RSGs, Minit = 10-40Msun) are known to eject largeamounts of material, as much as half of their initial mass during thisevolutionary phase. However, the processes powering the mass ejection in low-and intermediate-mass stars do not work for RSGs and the mechanism that drivesthe ejection remains unknown. Different mechanisms have been proposed asresponsible for this mass ejection but so far little is known about the actualprocesses taking place in these objects.  Here we present high angular resolution interferometric ALMA maps of VY CMacontinuum and molecular emission, which resolve the structure of the ejectawith unprecedented detail. The study of the molecular emission from the ejectaaround evolved stars has been shown to be an essential tool in determining thecharacteristics of the mass loss ejections. Our aim is thus to use theinformation provided by these observations to understand the ejectionsundergone by VY CMa and to determine their possible origins.  We inspected the kinematics of molecular emission observed. We obtainedposition-velocity diagrams and reconstructed the 3D structure of the gas tracedby the different species. It allowed us to study the morphology and kinematicsof the gas traced by the different species surrounding VY CMa.  Two types of ejecta are clearly observed: extended, irregular, and vastejecta surrounding the star that are carved by localized fast outflows. Thestructure of the outflows is found to be particularly flat. We present a 3Dreconstruction of these outflows and proof of the carving. This indicates thattwo different mass loss processes take place in this massive star. Wetentatively propose the physical cause for the formation of both types ofstructures. These results provide essential information on the mass lossprocesses of RSGs and thus of their further evolution.

History of two mass loss processes in VY CMa. Fast outflows carving older ejecta