  Red supergiant stars (RSGs, Minit = 10-40Msun) are known to eject large
amounts of material, as much as half of their initial mass during this
evolutionary phase. However, the processes powering the mass ejection in low-
and intermediate-mass stars do not work for RSGs and the mechanism that drives
the ejection remains unknown. Different mechanisms have been proposed as
responsible for this mass ejection but so far little is known about the actual
processes taking place in these objects.
  Here we present high angular resolution interferometric ALMA maps of VY CMa
continuum and molecular emission, which resolve the structure of the ejecta
with unprecedented detail. The study of the molecular emission from the ejecta
around evolved stars has been shown to be an essential tool in determining the
characteristics of the mass loss ejections. Our aim is thus to use the
information provided by these observations to understand the ejections
undergone by VY CMa and to determine their possible origins.
  We inspected the kinematics of molecular emission observed. We obtained
position-velocity diagrams and reconstructed the 3D structure of the gas traced
by the different species. It allowed us to study the morphology and kinematics
of the gas traced by the different species surrounding VY CMa.
  Two types of ejecta are clearly observed: extended, irregular, and vast
ejecta surrounding the star that are carved by localized fast outflows. The
structure of the outflows is found to be particularly flat. We present a 3D
reconstruction of these outflows and proof of the carving. This indicates that
two different mass loss processes take place in this massive star. We
tentatively propose the physical cause for the formation of both types of
structures. These results provide essential information on the mass loss
processes of RSGs and thus of their further evolution.
