  We propose a mechanism which provides an explanation of the Gallium and
antineutrino reactor anomalies. Differently from original Pontecorvo's
hypothesis, this mechanism is based on the phenomenological assumption in which
the admixture of neutrino mass eigenstates in the moments of neutrino creation
and detection can assume different configurations around the admixture
parametrized by the usual values of the mixing angles $\theta_{12}$,
$\theta_{23}$ and $\theta_{13}$. For simplicity, we assume a Gaussian
distribution for the mixing angles in such a way that the average value of this
distribution is given by the usual values of the mixing angles and the width of
the Gaussian is denoted by $\alpha$. We show that the proposed mechanism
provides a possible explanation for very short-baseline neutrino disappearance,
necessary to accommodate Gallium and antineutrino reactor anomalies, which is
not allowed in usual neutrino oscillations based on Pontecorvo's original
hypotheses. We also can describe high-energy oscillation experiments, like
LSND, Fermi and NuTeV, assuming a weakly energy dependent width parameter,
$\alpha(E)$, that nicely fits all experimental results.
