  We investigate the morphological and magnetic characteristics of solar active
region (AR) NOAA 12192. AR 12192 was the largest region of Solar Cycle 24; it
underwent noticeable growth and produced 6 X-class flares, 22 M-class flares,
and 53 C-class flares in the course of its disc passage. However, the most
peculiar fact of this AR is that it was associated with only one CME in spite
of producing several X-class flares. In this work, we carry out a comparative
study between the eruptive and non-eruptive flares produced by AR 12192. We
find that the magnitude of abrupt and permanent changes in the horizontal
magnetic field and Lorentz force are significantly smaller in the case of the
confined flares compared to the eruptive one. We present the areal evolution of
AR 12192 during its disc passage. We find the flare-related morphological
changes to be weaker during the confined flares, whereas the eruptive flare
exhibits a rapid and permanent disappearance of penumbral area away from the
magnetic neutral line after the flare. Furthermore, from the extrapolated
nonlinear force-free magnetic field, we examine the overlying coronal magnetic
environment over the eruptive and non-eruptive zones of the AR. We find that
the critical decay index for the onset of torus instability was achieved at a
lower height over the eruptive flaring region, than for the non-eruptive core
area. These results suggest that the decay rate of the gradient of overlying
magnetic field strength may play a decisive role to determine the CME
productivity of the AR. In addition, the magnitude of changes in the
flare-related magnetic characteristics are found to be well correlated with the
nature of solar eruptions.
