  We excite an epicyclic motion, whose amplitude depends on the vertical
position, $z$, in a simulation of a turbulent accretion disc. An epicyclic
motion of this kind may be caused by a warping of the disc. By studying how the
epicyclic motion decays we can obtain information about the interaction between
the warp and the disc turbulence. A high amplitude epicyclic motion decays
first by exciting inertial waves through a parametric instability, but its
subsequent exponential damping may be reproduced by a turbulent viscosity. We
estimate the effective viscosity parameter, $\alpha_{\rm v}$, pertaining to
such a vertical shear. We also gain new information on the properties of the
disc turbulence in general, and measure the usual viscosity parameter,
$\alpha_{\rm h}$, pertaining to a horizontal (Keplerian) shear. We find that,
as is often assumed in theoretical studies, $\alpha_{\rm v}$ is approximately
equal to $\alpha_{\rm h}$ and both are much less than unity, for the field
strengths achieved in our local box calculations of turbulence. In view of the
smallness ($\sim 0.01$) of $\alpha_{\rm v}$ and $\alpha_{\rm h}$ we conclude
that for $\beta = p_{\rm gas}/p_{\rm mag} \sim 10$ the timescale for diffusion
or damping of a warp is much shorter than the usual viscous timescale. Finally,
we review the astrophysical implications.
