  ASDEX Upgrade has developed multiple massive gas injection (MGI) scenarios to
investigate runaway electron (RE) dynamics. During the current quench of the
MGI induced disruptions, Alfv\'enic activity is observed in the 300-800 kHz
range. With the help of a mode tracing algorithm based on Fourier spectrograms,
mode behaviour was classified for 180 discharges. The modes have been
identified as global Alfv\'en eigenmodes using linear gyrokinetic MHD
simulations. Changes in the Alfv\'en continuum during the quench are proposed
as explanation for the strong frequency sweep observed. A systematic
statistical analysis shows no significant connection of the mode
characteristics to the dynamics of the subsequent runaway electron beams. In
our studies, the appearance and amplitude of the modes does not seem to affect
the potential subsequent runaway beam. Beyond the scope of the 180 investigated
dedicated RE experiments, the Alfv\'enic activity is also observed in natural
disruptions with no RE beam forming.
