  Statistical parameters of the ISM driven by thermal energy injections from
supernova explosions have been obtained from 3D, nonlinear,
magnetohydrodynamic, shearing-box simulations for spiral arm and interarm
regions. The density scale height obtained for the interarm regions is 50%
larger than within the spiral arms because of the higher gas temperature. The
filling factor of the hot gas is also significantly larger between the arms and
depends sensitively on magnetic field strength.
