  The shear and interface modes excited inside the neutron star due to the
presence of elasticity depend on the properties of both the crust and core
region. To examine how such eigenfrequencies depend on the neutron star
properties, we solve the eigenvalue problem by adopting the relativistic
Cowling approximation. Then, we confirm that the number of the interface modes
excited in the star is generally equivalent to the number of the interface
where the shear modulus discontinuously becomes zero, but we also find that the
number of interface modes becomes smaller than that of the interface for the
stellar model with lower or higher value of the slope parameter $L$.
Furthermore, we derive the empirical relations for expressing the shear modes
and one of the interface modes ($i_1$-mode in the text), which is the mode
whose amplitude becomes dominant at the interface between the crust and
envelopes and at the interface between the phases of slablike and cylindrical
nuclei. At the end, we also show the possibility of identifying the higher QPO
frequencies observed in GRB 200415A with the shear oscillations, as an
alternative possibility instead of the torsional oscillations.
