  Pulsars undergoing crustquake release strain energy, which can be absorbed in
a small region inside the inner crust of the star and excite the free
superfluid neutrons therein. The scattering of these neutrons with the
surrounding pinned vortices may unpin a large number of vortices and
effectively reduce the pinning force on vortex lines. Such unpinning by neutron
scattering can produce glitches for Crab like pulsars and Vela pulsar of size
in the range $\sim 10^{-8} - 10^{-7}$, and $\sim 10^{-9} - 10^{-8}$,
respectively. Although we discuss here the crustquake initiated excitation, the
proposal is very generic and equally applicable for any other sources, which
can excite the free superfluid neutrons, or can be responsible for superfluid -
normal phase transition of neutron superfluid in the inner crust of a pulsar.
