Seismoelectric Interface Response at Dipping Layer Boundaries

Abstract

Conceptual models and numerical modelling of seismoelectric effects indicate that the seismoelectric interface response, generated by seismic-to-electromagnetic field conversion at lithological interfaces in the subsurface, should be a multiple electrical source. Due to the dominating dipole term, the seismoelectric interface response emanating from a horizontal boundary is expected to exhibit symmetry and amplitude characteristics similar to those of a vertical electrical dipole (VED) centred on the interface right below the seismic shot-point. However, in terms of dipping layers no general theoretical predictions concerning the anatomical and morphological aspects of the VED have been published so far. To gain insight into the difference of the spatio-temporal occurrence and evolution of the seismoelectric interface responses at horizontal versus dipping interfaces we run a series of numerical simulations. For the modelling, we made use of a simplified time-domain formulation of the coupled physical problem and its efficient implementation in a 2D finite-element framework. We show that there is a difference between the response patterns of the generated seismoelectric interface responses, which we relate to the effect of “Fresnel aperture”, depending on the dip of the converting layer boundary.