The mutual induction between the ionosphere and the earth has been suggested as one of the possible causes of the longitudinal inhomogeneities in the phase velocity of type II irregularities in the equatorial electrojet. From the analysis of the geomagnetic daily variations at equatorial latitudes in Peru, Nigeria, and central Africa, latitudinal profiles of the integrated current density and clear evidence of latitudinal discontinuities in the distribution of the earth conductivity were found in previous work. In the present paper a very high correlation is found between tectonic features and inhomogeneities both in the phase velocity and in the integrated current density. This shows that ionospheric inhomogeneities are related to specific lateral discontinuities in the conductivity of the upper layers of the earth. This result gives enough insight into that effect to allow its inclusion in future theoretical models.