An attempt is made to explain the behavior of the magneto-hydrodynamic (MHD) instabilities observed at values of the edge safety factor 3<q(a)<4, on the HT-7 superconducting tokamak. For the poloidal-magnetic-field fluctuations observed at the Mirnov coils, Mirnov-coil analysis shows that the MHD activity consists predominantly of m=2 mode. Estimates are given for the characteristic growth time of the m=2 mode, τg, and the related rate of island growth, dW/dt. The experimental value of τg is found to be smaller than the linear theoretical one, and thus satisfy the condition τA<τg<τS (where ideal timescale is τA, and the resistive timescale is τS). However, the experimental and theoretical calculation of dW/dt are found to be in reasonable agreement with each other.