  We discuss the possibility that the strain field introduced by the structural
supermodulation in Bi-2212 and certain other cuprate materials may modulate the
superconducting pairing interaction. We calculate the amplitude of this effect,
visible in scanning tunneling spectroscopy experiments, and thereby relate a
change in the local superconducting gap with the change in the local dopant
displacements induced by the supermodulation. In principle, since this
modulation is periodic, sufficiently accurate x-ray measurements or ab initio
calculations should enable one to determine which atomic displacements enhance
pairing and therefore T_c.
