  Our understanding of protoplanetary disks is rapidly departing from the
classical view of a smooth, axisymmetric disk. This is in part thanks to the
high angular resolution that (sub)mm observations can provide. Here we present
the combined results of ALMA (0.9 mm) and VLA (7 mm) dust continuum
observations toward the protoplanetary disk around the solar analogue GM Aur.
Both images clearly resolve the $\sim$35 au inner cavity. The ALMA observations
also reveal a fainter disk that extends up to $\sim250$ au. We model our
observations using two approaches: an analytical fit to the observed
deprojected visibilities, and a physical disk model that fits the SED as well
as the VLA and ALMA observations. Despite not being evident in the deconvolved
images, the VLA and ALMA visibilities can only be fitted with two bright rings
of radii $\sim$40 and $\sim$80 au. Our physical model indicates that this
morphology is the result of an accumulation or trapping of large dust grains,
probably due to the presence of two pressure bumps in the disk. Even though
alternative mechanisms cannot be discarded, the multiple rings suggest that
forming planets may have cleared at least two gaps in the disk. Finally, our
analysis suggests that the inner cavity might display different sizes at 0.9 mm
and 7 mm. This discrepancy could be caused by the presence of free-free
emission close to the star at 7 mm, or by a more compact accumulation of the
large dust grains at the edge of the cavity.
