We present the results of three-dimensional global magnetohydrodynamic ( MHD ) simulations of the Parker-shearing instability in a differentially rotating torus initially threaded by toroidal magnetic fields .
An equilibrium model of magnetized torus is adopted as an initial condition .
When \beta _ { 0 } = P _ { gas } / P _ { mag } \sim 1 at the initial state , magnetic flux buoyantly escapes from the disk and creates loop-like structures similar to those in the solar corona .
Inside the torus , growth of non-axisymmetric magneto-rotational ( or Balbus & Hawley ) instability generates magnetic turbulence .
Magnetic field lines are tangled in small scale but in large scale they show low azimuthal wave number spiral structure .
After several rotation period , the system oscillates around a state with \beta \sim 5 .
We found that magnetic pressure dominated ( \beta < 1 ) filaments are created in the torus .
The volume filling factor of the region where \beta \leq 0.3 is 2-10 % .
Magnetic energy release in such low- \beta regions may lead to violent flaring activities in accretion disks and in galactic gas disks .