We identify sites of apparent flexural uplift at rift zone boundaries on Ganymede using Galileo stereo-derived topography. The estimated effective elastic thickness te is 0.9--1.7 km for a nominal Young's modulus of 1 GPa. Using a viscoelastic model of the ice crust we find that the temperature defining the base of the elastic layer is <185 K for likely strain rates. The inferred local heat flux during deformation is less than 245 mW m-2, and probably close to 100 mW m-2. The stresses required to cause fault motion are around 1 MPa. Both the high heat flux and the high stresses are consistent with estimates of these quantities during an episode of transient tidal heating in Ganymede's past.