The vertical dipole-like model for interfacial seismoelectric sources is supported by measurements of signal amplitude vs. receiver offset (AVO) at the ground surface (e.g.Butler et al. 1996; Dupuis et al. 2007; Strahser et al. 2007) and amplitude vs. receiver depth in a borehole (Dupuis et al. 2009). However, recent lab experiments by Schakel et al. (2012) have reinforced the observation by Dupuis et al. (2007) that the rate of decay of signal amplitude with offset is slightly less than predicted by the simple vertical dipole model.