  The nonlinear evolution of the m=1 internal kink mode is studied numerically
in a setting where the tokamak core plasma is surrounded by a turbulent region
with low magnetic shear. As a starting point we choose configurations with
three nearby q=1 surfaces where triple tearing modes (TTMs) with high poloidal
mode numbers m are unstable. While the amplitudes are still small, the fast
growing high-m TTMs enhance the growth of the m=1 instability. This is
interpreted as a fast sawtooth trigger mechanism. The TTMs lead to a partial
collapse, leaving behind a turbulent belt with q ~= 1 around the unreconnected
core plasma. Although, full reconnection can occur if the core displacement
grows large enough, it is shown that the turbulence may actively prevent
further reconnection. This is qualitatively similar to experimentally observed
partial sawtooth crashes with post-cursor oscillations due to a saturated
internal kink.
