  We study recent observations of propagating fluctuations in a prominence foot
with Hinode Solar Optical Telescope (SOT) high-resolution observations in Ca~II
and H alpha emission which we identify as nonlinear fast magnetosnic waves.
Here we analyze further the observations of propagating waves and flows with
Interface Region Imaging Spectrograph (IRIS) Mg~II slit jaw images, in addition
to Hinode/SOT Ca~II images. We find that the waves have typical periods in the
range of 5 - 11 minutes and wavelengths in the plane of the sky (POS) of about
2000 km, while the flows in narrow threads have typical speed in the POS of
~16-46 km/s. We also detect apparent kink oscillations in the threads with
flowing material, and apply coronal seismology to estimate the magnetic field
strength in the range 5-17 G. Using 2.5D MHD we model the combined effects of
nonlinear waves and flows on the observed dynamics of the prominence material,
and reproduce the propagating and refracting fast magnetosonic waves, as well
as standing kink-mode waves in flowing material along the magnetic field. The
modeling results are in good qualitative agreements with the observations of
the various waves and flows in the prominence foot, further confirming coronal
seismology analysis and improving the understanding of the fine scale dynamics
of the prominence material.
